Patent Description:
Hearing devices provide sound for the user. Some examples of hearing devices are headsets, hearing aids, speakers, cochlear implants, bone conduction devices, and personal listening devices. Hearing devices often include a rechargeable battery that can be recharged, but can become depleted during daily use, leaving the user without the benefit of a functioning hearing device.

<CIT> relates to a charger and a rechargeable device. The rechargeable device includes a power manager and a power storage device.

The present invention proposes a charging system as defined in claim <NUM> and an associated charging method according to claim <NUM>. Optional features of said system and method are defined in the corresponding dependent claims.

Various embodiments are directed to an apparatus comprising first and second hearing assistance devices each comprising a rechargeable power source and power management circuitry configured to control charging of the power sources. A portable charging unit comprises an interface configured to receive a connector of a power cable or a power and data cable, a rechargeable power source coupled to the interface, first and second charge ports configured to receive the first and second hearing assistance devices, and charging circuitry coupled to the first and second charge ports and to the rechargeable power source of the charging unit. The power management circuitry and the charging circuitry cooperate to partially charge the power sources of the hearing assistance devices at an accelerated charge rate above <NUM>. 0C when a state of charge (SoC) of the power sources is within a predetermined SoC range.

Some embodiments are directed to an apparatus including a portable charging unit comprising an interface configured to receive a connector of a power cable or a power and data cable, a rechargeable power source coupled to the interface, first and second charge ports configured to receive first and second rechargeable hearing assistance devices, and charging circuitry coupled to the first and second charge ports and to the rechargeable power source. The charging circuitry is configured to partially charge the power source at an accelerated charge rate above <NUM>. 0C when a SoC of the power source of the portable charging unit is within a predetermined SoC range.

Other embodiments are directed to an apparatus comprising first and second hearing assistance devices each comprising a rechargeable power source and power management circuitry configured to control charging of the power sources. A portable charging unit comprises an interface configured to receive a connector of a power cable or a power and data cable, a rechargeable power source coupled to the interface, first and second charge ports configured to receive the first and second hearing assistance devices, and charging circuitry coupled to the first and second charge ports and to the rechargeable power source. The power management circuitry and the charging circuitry cooperate to partially charge the power sources of the hearing assistance devices at an accelerated charge rate above <NUM>. 0C when a SoC of the power sources is within a predetermined SoC range. The charging circuitry is configured to partially charge the power source of the portable charging unit at an accelerated charge rate above <NUM>. 0C when a SoC of the power source of the portable charging unit is within a predetermined SoC range.

Various embodiments are directed to a method of charging rechargeable power sources of first and second hearing assistance devices using a portable rechargeable charging unit. The method comprises connecting the first and second hearing assistance devices (HADs) to the portable charging unit, determining a SoC of the HAD power sources, charging the HAD power sources at an accelerated charge rate above <NUM>. 0C in response to the SoC falling within a predetermined SoC range, and charging the HAD power sources at a normal charge rate at or below <NUM>. 0C in response to the SoC exceeding the predetermined SoC range.

Some embodiments are directed to a method of charging rechargeable power sources of first and second hearing assistance devices using a portable rechargeable charging unit. The method comprises determining, by the charging unit, a SoC of the power sources and whether the SoC is within a predetermined SoC range, and transmitting, in response to the SoC falling within the predetermined SoC range, an initiation signal from the charging unit to the first and second hearing assistance devices requesting that accelerated charging at an accelerated charge rate above <NUM>. 0C be initiated. The method also comprises controlling, by the first and second hearing assistance devices, charging of the power sources at the accelerated charge rate, and communicating charging data from the first and second hearing assistance devices to the charging unit during charging of the power sources. The method further comprises transmitting, in response to the SoC exceeding the predetermined SoC range, a termination signal from the charging unit to the first and second hearing assistance devices requesting that accelerated charging be terminated.

Other embodiments are directed to a method of charging a rechargeable power source of a portable charging unit comprising supplying power to the portable charging unit, determining a SoC of the power source, charging the power source at an accelerated charge rate above <NUM>. 0C in response to the SoC falling within a predetermined SoC range, and charging the power source at a normal charge rate at or below <NUM>. 0C in response to the SoC exceeding the predetermined SoC range.

The above summary is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The figures and the detailed description below more particularly exemplify illustrative embodiments.

Throughout the specification reference is made to the appended drawings wherein:.

However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number;.

A conventional approach to charging hearing assistance devices involves the use of a charging station designed to be placed on a table and plugged into a wall socket within a wearer's home. Typical charge times range between <NUM> and <NUM> hours to fully charge the hearing assistance devices using a conventional charging station. Conventional charging approaches fail to address a significant problem faced by on-the-go wearers of hearing assistance devices. During normal use of the hearing assistance devices away from the wearer's home (and charging station), the wearer may experience a "dead battery" scenario, which renders the hearing assistance devices temporarily inoperable. Although some on-the-go chargers have been developed, these require on the order of hours of recharge time. Moreover, during the charging procedure, the wearer must go without the benefit of the hearing assistance devices.

Embodiments of the disclosure are directed to a portable charging unit configured for charging one or more hearing assistance devices (HADs). The portable charging unit and the HADs are configured to implement accelerated charging of the HADs, by which rechargeable power sources of the HADs are partially charged within a very short timeframe. The term "accelerated charging" refers to charging a rechargeable power source (e.g., a battery) at an accelerated charge rate above <NUM>. 0C when the power source has a sufficiently low voltage or state of charge (SoC). Accelerated charging can be implemented to partially charge a rechargeable power source within a relatively short time frame, such that the power source has a storage capacity for several hours of use. Accelerated charging of a rechargeable power source can be implemented when the SoC of the power source is within a predetermined SoC range, such as between <NUM> and <NUM>%. Because the power source is at a low voltage or low SoC, the rate at which it can be charged can be increased beyond <NUM>. 0C without the risk of damaging the power source. For example, lithium plating can occur when charging a lithium-ion battery at charge rates above <NUM>. 0C, particularly when the battery is almost fully charged. However, it is been found that charging a lithium-ion battery at an accelerated charge rate above <NUM>. 0C (e.g., from <NUM>. 5C to <NUM>. 0C) when the SoC is within <NUM> to <NUM>% significantly decreases the risk of cell degradation due to lithium plating.

For example, after about <NUM> minutes of accelerated charging, a pair of HADs have sufficient charge for between <NUM> and <NUM> hours of use. According to some embodiments, the pair of HADs can be used by the wearer during a charging procedure, which can include accelerated charging. The portable charging unit includes a rechargeable power source that can be recharged using accelerated charging in accordance with embodiments of the disclosure. For example, after about <NUM> minutes of accelerated charging, the portable charging unit has enough capacity to supply a full charge to the pair of HADs and, in addition, perform accelerated charging of the HADs.

It is understood that the embodiments described herein may be used with any hearing assistance device without departing from the scope of this disclosure. The devices depicted in the figures are intended to demonstrate the subject matter, but not in a limited, exhaustive, or exclusive sense. Hearing assistance devices, such as hearables (e.g., wearable earphones, ear monitors, and earbuds) and hearing aids, typically include an enclosure, such as a housing or shell, within which internal components are disposed. Typical components of a hearing assistance device can include a digital signal processor (DSP), memory, power management circuitry, one or more communication devices (e.g., a near-field communication device, a long-range communication device), one or more antennas, one or more microphones, and a receiver/speaker, for example. Near-field magnetic induction communication circuitry can be implemented to facilitate communication between a left ear device and a right ear device. Hearing assistance devices can also incorporate a long-range communication device, such as a Bluetooth® transceiver or other type of radio frequency (RF) transceiver (e.g. a <NUM> radio). The transceiver can conform to an IEEE <NUM> (e.g., WiFi®) or Bluetooth® (e.g., BLE, Bluetooth® <NUM> or <NUM>) specification, for example. It is understood that hearing devices of the present disclosure can employ other radios, such as a <NUM> radio.

Hearing assistance devices of the present disclosure can be configured to receive streaming audio (e.g., digital audio data or files) from an electronic or digital source. Representative electronic/digital sources (e.g., accessory devices) include an assistive listening system, a TV streamer, a radio, a smartphone, a laptop, a cell phone/entertainment device (CPED) or other electronic device that serves as a source of digital audio data or other types of data files. Hearing assistance devices of the present disclosure can be configured to effect bi-directional communication (e.g., wireless communication) of data with an external source, such as a remote server via the Internet or other communication infrastructure.

The term hearing assistance device of the present disclosure refers to a wide variety of ear-level electronic devices that can aid a person with impaired hearing. The term hearing assistance device also refers to a wide variety of devices that can produce optimized or processed sound for persons with normal hearing. Hearing assistance devices of the present disclosure include hearables (e.g., wearable earphones, headphones, earbuds, virtual reality headsets), hearing aids (e.g., hearing instruments), cochlear implants, and bone-conduction devices, for example. Hearing assistance devices include, but are not limited to, behind-the-ear (BTE), in-the-ear (ITE), in-the-canal (ITC), invisible-in-canal (IIC), receiver-in-canal (RIC), receiver-in-the-ear (RITE) or completely-in-the-canal (CIC) type hearing devices or some combination of the above. Throughout this disclosure, reference is made to a "hearing assistance device," which is understood to refer to a system comprising one of a left ear device and a right ear device or a combination of a left ear device and a right ear device.

<FIG> shows a portable charging unit <NUM> in accordance with various embodiments. The portable charging unit <NUM> includes a housing <NUM> within which various components, including a rechargeable power source and charging circuitry, are disposed. The housing <NUM> includes a working surface <NUM> comprising a first charge port <NUM> and a second charge port <NUM>. Each of the charge ports <NUM>, <NUM> is configured to receive, and establish electrical connection with, a hearing assistance device. The portable charging unit <NUM> includes an interface <NUM> provided on a side surface <NUM> of the housing <NUM>. The interface <NUM> is configured to receive a connector of a power cable or a power and data cable. For example, the interface <NUM> can be configured to mechanically and electrically connect to a USB cable (e.g., micro B, OTG) or a Lightning cable. Various types of data can be communicated between the portable charging unit <NUM>, hearing assistance devices, and an external system (e.g., laptop, PC, tablet, smartphone) via the interface <NUM>, such as charging status, maintenance messages, device use/user statistics, and audio to or from the unit <NUM>, the hearing assistance device, or a hearing assistance accessory. Although not shown in the embodiment of <FIG>, the working surface <NUM> of the housing <NUM> can support a user interface, such as a display (e.g., LED, LCD, OLED, E-ink) and/or one or more LEDs.

The housing <NUM> of the portable charging unit <NUM> is dimensioned for portability, such that it can be carried in a pocket of apparel or in a small handbag. The housing <NUM> can be formed from a plastic material and have a length ranging from about <NUM> inches to <NUM> inches, a width ranging from about <NUM> inches to <NUM> inches, and a depth ranging from about <NUM>/<NUM> inches to <NUM> inch. For example, the housing <NUM> can have a length of <NUM> inches, a width of <NUM> inches, and a depth of <NUM>/<NUM> of an inch. The charge ports <NUM>, <NUM> define recessed regions of the working surface <NUM>. Each of the charge ports <NUM>, <NUM> includes electrical contacts for establishing electrical connection with a hearing assistance device, and further includes a retention arrangement configured to retain the hearing assistance devices within the charge ports <NUM>, <NUM>. The retention arrangement can be a mechanical arrangement (e.g., a spring mechanism or interference fit arrangement) or a magnetic arrangement, for example.

<FIG> shows a protective sleeve <NUM> having open sides <NUM> and <NUM> for receiving the portable charging unit <NUM>. The protective sleeve <NUM> is typically formed from a plastic material. To protect the working surface <NUM> (e.g., the electrical contacts of the charge ports <NUM>, <NUM> during transport), the portable charging unit <NUM> can be slid into the protective sleeve <NUM> via one of the open sides <NUM>, <NUM>. <FIG> shows the portable charging unit <NUM> covered by the protective sleeve <NUM>. The protective sleeve <NUM> can also serve as a base for the portable charging unit <NUM>, which elevates the charging unit <NUM> relative to the surface upon which the protective sleeve <NUM> is placed. This arrangement is particularly useful for hearing assistance devices that include a small wire running around the ear and into the ear canal which connects to a receiver or speaker (e.g., a receiver-in-canal hearing aid, as shown in <FIG>). Stacking the portable charging unit <NUM> on top of the protective sleeve <NUM> allows the wire and receiver to drape over the side of the portable charging unit <NUM>, ensuring good retention of the hearing assistance devices within the charge ports <NUM>, <NUM>.

<FIG> show various features of a portable charging unit <NUM> in accordance with various embodiments. In particular, the working surface <NUM> of the housing <NUM> includes a first charge port <NUM> configured to receive a first hearing assistance device <NUM> and a second charge port <NUM> configured to receive a second hearing assistance device <NUM>. The first charge port <NUM> defines a recessed region of the working surface <NUM> having a shape that corresponds to a shape of the distal end of the first hearing assistance device <NUM>. The second charge port <NUM> defines a recessed region of the working surface <NUM> having a shape that corresponds to a shape of the distal end of the second hearing assistance device <NUM>. The first charge port <NUM> includes a first electrical contact 208a and a second electrical contact 208b, which are configured to connect with corresponding electrical contacts disposed on the distal end of the first hearing assistance device <NUM>. The second charge port includes an electrical contact 218a and a second electrical contact 218b, which are configured to connect with corresponding electrical contacts disposed on the distal end of the second hearing assistance device <NUM>. Each of the first and second charge ports <NUM>, <NUM> includes a retention arrangement comprising a magnet <NUM>, <NUM>. The magnets <NUM>, <NUM> interact magnetically with a corresponding magnet or ferrous material (e.g., ferrous material of a battery) disposed within the distal end of the first and second hearing assistance devices <NUM>, <NUM>. The magnets <NUM>, <NUM> serve to mechanically retain the first and second hearing assistance devices <NUM>, <NUM> within the first and second charge ports <NUM>, <NUM> during a charging procedure.

According to various embodiments, and as shown in <FIG>, a portable charging unit <NUM> can be configured to connect with a number of different accessory devices. <FIG> shows a representative accessory device <NUM> which includes a contacting surface <NUM> and an opposing working surface <NUM> (not shown). As shown, the accessory device <NUM> has a length and width corresponding to that of the portable charging unit <NUM>, although this is not required. In this regard, the accessory device <NUM> and the portable charging unit <NUM> are stackable. The contacting surface <NUM> of the accessory device <NUM> includes first and second connectors <NUM>, <NUM> that protrude from the contacting surface <NUM>. The first and second connectors <NUM>, <NUM> have a shape that corresponds to a shape of the first and second charge ports <NUM>, <NUM>. The first and second connectors <NUM>, <NUM> have a height that corresponds to a depth of the first and second charge ports <NUM>, <NUM>.

As is shown in <FIG>, the first charge port <NUM> includes a first electrical contact 308a, a second electrical contact 308b, and a magnet <NUM>. The second charge port <NUM> includes a first electrical contact 318a, a second electrical contact 318b, and a magnet <NUM>. As is shown in <FIG>, the first connector <NUM> includes a first electrical contact 348a, a second electrical contact 348b, and a magnet <NUM> (or ferromagnetic material such as iron). The second connector <NUM> includes a first electrical contact 368a, a second electrical contact 368b, and a magnet <NUM> (or ferromagnetic material such as iron). When the first and second connectors <NUM>, <NUM> of the accessory device <NUM> are inserted into the charge ports <NUM>, <NUM> of the portable charging unit <NUM>, the contacting surface <NUM> of the accessory device <NUM> matingly engages the working surface <NUM> of the portable charging unit <NUM>. In this configuration, the electrical contacts 348a, 348b, 368a, 368b of the accessory device <NUM> electrically connect with the electrical contacts 308a, 308b, 318a, 318b of the portable charging unit <NUM>. Mating engagement between the portable charging unit <NUM> and the accessory device <NUM> is maintained by a magnetic attraction force generated by magnet pairs <NUM>, <NUM> and <NUM>, <NUM>. The magnetic attraction force can be defeated by manually separating the accessory device <NUM> and the portable charging unit <NUM>.

<FIG> illustrates an accessory device <NUM> configured to physically and electrically connect with a portable charging unit <NUM> in accordance with various embodiments. In this illustrative embodiment, the accessory device <NUM> is a remote control unit configured to communicate with, and control various functions of, a pair of hearing assistance devices. When connected to the portable charging unit <NUM> (e.g., in the manner illustrated in <FIG>), the remote control unit <NUM> draws power from the rechargeable power source of the portable charging unit <NUM>. A slider <NUM> allows the user to turn the remote control unit <NUM> off and on. A slider <NUM> allows the user to select between a first (e.g., left) hearing assistance device and a second (e.g., right) hearing assistance device. The volume of the first and second hearing assistance devices can be adjusted using a volume increase button <NUM> and a volume decrease button <NUM>. A mute button <NUM> is also provided for muting the first and second hearing assistance devices. The remote control unit <NUM> also includes a program selection button <NUM>, a favorite button <NUM> for selecting a favorite memory or other feature or configuration, and a home button <NUM>, which can enables a favorite mode of operation. It is understood that the functions described above represent non-exhaustive examples of functions that can be performed using the remote control unit <NUM>. The remote control unit <NUM> can be less or more complex. For example, the remote control unit <NUM> can have only three buttons: a volume increase button, a volume decrease button, and a memory button.

<FIG> illustrates an accessory device <NUM> configured to physically and electrically connect to a portable charging unit <NUM> in accordance with various embodiments. In this illustrative embodiment, the accessory device <NUM> is a solar power accessory which includes a solar cell <NUM>. The solar power accessory <NUM>, when connected to the portable charging unit <NUM> and exposed to light, generates a charging current that recharges the rechargeable power source of the portable charging unit <NUM>.

In accordance with other embodiments, an accessory device as shown in <FIG> can include one or more physiologic sensors. For example, the accessory device <NUM> shown in <FIG> can include an EKG or ECG sensor, a pulse oximeter, a respiration sensor, a temperature sensor, a glucose sensor, an EEG sensor, an EMG sensor, an EOG sensor, or a galvanic skin response sensor. Representative examples of such sensors that can be implemented in the accessory devices shown in <FIG> are disclosed in <CIT>), <CIT>)<CIT>), and in <CIT>) and <CIT>).

<FIG> shows a portable charging unit <NUM> configured to facilitate accelerated charging of a pair of hearing assistance devices <NUM>, <NUM> in accordance with various embodiments. The portable charging unit <NUM> includes recessed first and second charge ports <NUM>, <NUM> configured to receive first and second hearing assistance devices <NUM>, <NUM>. When inserted into the first charge port <NUM>, the first and second electrical contacts <NUM>, <NUM> of the first hearing assistance device <NUM> connect with the first and second electrical contacts <NUM>, <NUM> of the first charge port <NUM>. When inserted into the second charge port <NUM>, the first and second electrical contacts <NUM>, <NUM> of the second hearing assistance device <NUM> connect with the first and second electrical contacts <NUM>, <NUM> of the second charge port <NUM>. The first hearing assistance device <NUM> is retained within the first charge port <NUM> by a magnetic attraction force generated by magnet <NUM> and magnet/magnetic material <NUM>. The second hearing assistance device <NUM> is retained within the second charge port <NUM> by a magnetic attraction force generated by magnet <NUM> and magnet/magnetic material <NUM>. In an alternative embodiment, the magnets <NUM>, <NUM> can be replaced by first and second spring-like electrical contacts mounted on sidewalls of the first and second charge ports <NUM>, <NUM> (shown in dotted lines). The spring-like electrical contacts generate a spring force that retains the first and second hearing assistance devices <NUM>, <NUM> within the first and second charge port <NUM>, <NUM>. In such an embodiment, the first and second electrical contacts <NUM>, <NUM>, <NUM>, <NUM> are disposed on a distal sidewall surface of the first and second hearing assistance devices <NUM>, <NUM>.

The portable charging unit <NUM> includes an interface <NUM> configured to receive a connector of a power cable or a combined power/data cable (e.g., USD or Lightning cable). The portable charging unit <NUM> also includes a rechargeable power source <NUM>, such as a lithium-ion battery, and charging circuitry <NUM>. The charging circuitry <NUM> is coupled to the rechargeable power source <NUM> and the first and second charge ports <NUM>, <NUM>. The rechargeable power source <NUM> can have a capacity ranging between about <NUM> to <NUM> mAh (e.g., <NUM> mAh). In general, for lithium-ion type batteries, the rechargeable power source <NUM> can be oversized by a factor of about <NUM> relative to the energy required to fully charge the first and second hearing assistance devices <NUM>, <NUM> from fully dead for the life of the devices. It is understood that the rechargeable power source <NUM> need not be a lithium-ion battery. For example, the rechargeable power source <NUM> can be a high power density type such as thin film Li-ion, Li-titanate, Li-titanate supercapacitor hybrid, or other type of supercapacitor. These high power cells do not need to be oversized.

The first hearing assistance device <NUM> includes a rechargeable power source <NUM> coupled to power management circuitry <NUM>. The second hearing assistance device <NUM> includes a rechargeable power source <NUM> coupled to power management circuitry <NUM>. The power sources <NUM>, <NUM> can be Li-ion batteries having a capacity ranging between about <NUM> and <NUM> mAh (e.g., <NUM> mAh). In some embodiments, the power sources <NUM>, <NUM> can have a capacity of up to <NUM> mAh (e.g., for larger hearables). It is understood that the power sources <NUM>, <NUM> can alternatively be of a high power density type as described hereinabove.

The power management circuitry <NUM>, <NUM> is configured to communicate with the charging circuitry <NUM> of the portable charging unit <NUM> to control charging of the respective power sources <NUM>, <NUM>. As will be described in greater detail hereinbelow, the power management circuitry <NUM>, <NUM> and charging circuitry <NUM> cooperate to partially charge the power sources <NUM>, <NUM> of the hearing assistance devices <NUM>, <NUM> at an accelerated charge rate above <NUM>. 0C (e.g., <NUM>. 0C) when a state of charge (SoC) of the power sources <NUM>, <NUM> is within a predetermined SoC range (or a predetermined voltage range, e.g., <NUM>-<NUM> V). For example, the predetermined SoC range is a range from a fully discharged state to about <NUM>% (e.g., <NUM>%-<NUM>%, such as <NUM>%-<NUM>%). Charging at the accelerated charge rate is terminated in response to one or more of reaching a predetermined time limit (e.g., <NUM> minutes), a predetermined voltage limit (e.g., <NUM>. 1V), or reaching a predetermined energy limit (e.g., <NUM> mAh out of a possible <NUM> mAh). After about <NUM> minutes of accelerated charging, for example, the power sources <NUM>, <NUM> of the first and second hearing assistance devices <NUM>, <NUM> have a capacity sufficient for about <NUM> to <NUM> hours of normal operation.

When the SoC of the power sources <NUM>, <NUM> is outside of the predetermined SoC range, the power management circuitry <NUM>, <NUM> and charging circuitry <NUM> cooperate to charge the power sources <NUM>, <NUM> of the hearing assistance devices <NUM>, <NUM> at a normal charge rate at or below <NUM>. 0C, such as at <NUM>. 3C (e.g., when it is desired to fully charge the power sources <NUM>, <NUM>). It is noted that the charging current associated with the accelerated charge rate is typically greater than a charging current associated with the normal charge rate by a factor of about <NUM> to <NUM>. For example, the charging current associated with the normal charge rate can be about <NUM> mA (e.g., at <NUM>. 3C), whereas the charging current associated with the accelerated charge rate can be between <NUM> and <NUM> mA (e.g., at <NUM>.

The portable charging unit <NUM> shown in <FIG> also includes a user interface <NUM>. In some embodiments, and with reference to <FIG>, the user interface <NUM> can include a display <NUM>, such as an LED or OLED display. In addition, or alternatively, the user interface <NUM> can include one or more LEDs <NUM> (e.g., four LEDs). The LEDs <NUM> can be controlled to communicate various types of information to the user. For example, solid red on an LED near the first hearing assistance device <NUM> can indicate a charging error for the first hearing assistance device <NUM>. Solid red on an LED near the second hearing assistance device <NUM> can indicate a charging error for the second hearing assistance device <NUM>. A pulsing green on an LED near the first hearing assistance device <NUM> can indicate charging of the first hearing assistance device <NUM>. A pulsing green on an LED near the second hearing assistance device <NUM> can indicate charging of the second hearing assistance device <NUM>. Accelerated charging of each of the first and second hearing assistance devices <NUM>, <NUM> can be indicated by a flashing green LED, a green LED bouncing back and forth (knight rider, similar to a line marquee), or a fast pulsing green LED. A solid green LED near each of the first and second hearing assistance devices <NUM>, <NUM> can indicate that charging is complete. Normal rate charging of the portable charging unit <NUM> may be indicated, for example, by using all four LEDs <NUM> to indicate <NUM>, <NUM>, <NUM>, and <NUM>% SOC. One LED is lit per quarter SOC attained during charging. The remaining LEDs <NUM> may pulse at a given rate. To indicate accelerated charging of the portable charging unit <NUM>, the LEDs <NUM> may pulse at a faster rate.

The user interface <NUM> can also include an accelerometer <NUM> configured to be responsive to taps applied to the housing of the portable charge unit <NUM>. The number and/or sequence of taps as detected by the accelerometer <NUM> can correspond to various inputs communicated by the user. Single, double, and triple taps, for example, can correspond to three different input commands received from the user. For example, a single tap can correspond to a command that turns the user interface <NUM> ON/OFF. A double tap can correspond to a command that causes cycling through user interface status indicators (e.g., on-board battery status, individual hearing assistance device battery status). A triple tap can correspond to a command to start/stop accelerated charging of the first and second hearing assistance devices <NUM>, <NUM>. In some embodiments, accelerated charging is initiated automatically by the charging circuitry <NUM> and power management circuitry <NUM>, <NUM>. In other embodiments, accelerated charging can be initiated in response to a tap or tap sequence (e.g., a triple tap) detected by the accelerometer <NUM>.

By way of further example, a single tap can correspond to a command to illuminate one or more LEDs to indicate onboard battery status of the portable charging unit <NUM>. A double tap can correspond to a command to turn off the LED(s). Alternatively, and assuming no hearing assistance devices <NUM>, <NUM> are attached to the portable charging unit <NUM>, a double tap can correspond to a command to illuminate one or more LEDs to indicate onboard battery status of the portable charging unit <NUM> followed by a command to turn off the LED(s). If one or both hearing assistance devices <NUM>, <NUM> are attached to the portable charging unit <NUM>, a double tap can correspond to a command to illuminate one or more LEDs to indicate battery status of the hearing assistance devices <NUM>, <NUM>, followed by a command to turn off the LED(s). A triple tap can correspond to a command that places the portable charging unit <NUM> in a low power standby mode in order to conserve the stored charge over a long period of time.

The accelerometer <NUM> may also be configured to detect shaking of the portable charging unit <NUM> as a method of user input. Shaking the portable charging unit <NUM> in an up and down, left or right, or in and out motion may be interchanged with any single, double, or triple tap mechanism as a method of user input as described in previous examples. In some embodiments, the portable charging unit <NUM> employs the accelerometer <NUM> to detect a linear motion along one axis in three-dimensional space. This linear motion is considered to be an acceptable shaking motion when one of the following conditions is satisfied in a given time period: velocity or acceleration along a linear axis exceeds a magnitude and alternates in direction on the linear axis, variance of acceleration samples exceeds a minimum value. For example, the accelerometer <NUM> can be configured to detect a shaking motion for an up and down axis or a left and right axis. The accelerometer <NUM> can be configured to detect a motion measuring a linear acceleration of more than <NUM>/s<NUM> upwards and then <NUM>/s<NUM> downwards in <NUM> second intervals. A detected shake can correspond to a command that places the portable charging unit <NUM> in a low power standby mode in order to conserve the stored charge over a long period of time.

The accelerometer <NUM> may also be configured to detect a fall of the portable charging unit <NUM> and a subsequent impact or an impact alone as a method of user input for the purpose of detecting an impact to the portable charging unit <NUM> exceeding design specification. To detect a fall, the portable charging unit <NUM> is configured to measure a linear motion of about <NUM>/s<NUM> for a minimum period of time. To detect an impact, the accelerometer <NUM> can be configured to detect a change in linear acceleration exceeding a specified amount. A detected fall and subsequent impact event, or a detected impact event alone, can be recorded in non-volatile memory (e.g., of microcontroller <NUM> in <FIG>) of the portable charging unit <NUM> and counted as an event. The number of falls and impact events, or impact only events, can be retrieved from non-volatile memory using the programming interface of the microcontroller.

<FIG> illustrates a method of implementing accelerated charging of one or a pair of hearing assistance devices in accordance with various embodiments. The method shown in <FIG> involves establishing connection <NUM> between first and/or second hearing assistance devices and a portable rechargeable charging unit. The method involves determining <NUM> the SoC of the HAD power sources. A check <NUM> is made to determine if the SoC of the HAD power sources is within a predetermined SoC range (e.g., <NUM>-<NUM>%). If the SoC of the HAD power sources fall within the predetermined SoC range, the method involves charging <NUM> the HAD power sources at an accelerated charge rate above <NUM>. 0C (e.g., <NUM>. 5C - <NUM>. Accelerated charging continues while the SoC of the HAD power sources remain within the predetermined SoC range. Accelerated charging is discontinued when the SoC of the HAD power sources is beyond the predetermined SoC range. In some embodiments, accelerated charging is discontinued in response to expiration of a predetermined time limit (e.g., <NUM> minutes), reaching a predetermined voltage limit (e.g., <NUM>. 1V), or reaching a predetermined energy limit (e.g., <NUM> mAh).

At the termination of accelerated charging, the user may remove the hearing assistance devices from the portable charging unit and immediately use the devices. As was discussed previously, five minutes of accelerated charging allows the hearing assistance devices to be used for between <NUM> and <NUM> hours of normal operation. Rather than using the hearing assistance devices after termination of accelerated charging, the method can involve charging <NUM> the HAD power sources at a normal charge rate at or below <NUM> C. A check <NUM> is made to determine if the HAD power sources are fully charged. If not, charging at the normal charge rate continues. When the HAD power sources are fully charged, the charging procedure is terminated <NUM>.

<FIG> illustrates a method of implementing accelerated charging of a portable rechargeable charging unit in accordance with various embodiments. The method shown in <FIG> involves supplying power to the portable charging unit, such as from a standard wall socket. The method involves determining <NUM> the SoC of the rechargeable power source of the portable charging unit. A check <NUM> is made to determine if the SoC of the power source is within a predetermined SoC range (e.g., <NUM>-<NUM>%). If the SoC of the power source falls within the predetermined SoC range, the method involves charging <NUM> the power source of the portable charging unit at an accelerated charge rate above <NUM>. 0C (e.g., <NUM>. 5C - <NUM>. Accelerated charging continues while the SoC of the power source remains within the predetermined SoC range. Accelerated charging is discontinued when the SoC of the power source is beyond the predetermined SoC range. In some embodiments, accelerated charging is discontinued in response to expiration of a predetermined time limit (e.g., <NUM> minutes), reaching a predetermined voltage limit (e.g., <NUM>. 1V), or reaching a predetermined energy limit (e.g., <NUM> mAh).

At the termination of accelerated charging, the user may disconnect the portable charging unit from the power source for immediate use or transport. Partially charging the power source of the portable charging unit at the accelerated charge rate for about <NUM> minutes charges the power source for at least about <NUM> hours of use. For example, after about <NUM> minutes of accelerated charging, the portable charging unit has enough capacity to supply a full charge to a pair of HADs and, in addition, to perform accelerated charging of the HADs. Rather than using or transporting the portable charging unit after termination of accelerated charging, the method can involve charging <NUM> the power source at a normal charge rate at or below <NUM> C. A check <NUM> is made to determine if the power source is fully charged. If not, charging at the normal charge rate continues. When the power source of the portable charging unit is fully charged, the charging procedure is terminated <NUM>.

<FIG> illustrates a method of implementing accelerated charging of one or a pair of hearing assistance devices in accordance with various embodiments. The method shown in <FIG> involves establishing connection <NUM> between first and/or second hearing assistance devices and a portable rechargeable charging unit. The method involves determining <NUM>, by the charging unit, the SoC of the HAD power sources and whether the SoC is within a predetermined SoC range. The method also involves transmitting <NUM>, in response to the SoC falling within the predetermined SoC range, and initiation signal from the charging unit to the first and/or second HADs requesting that accelerated charging at an accelerated charge rate above <NUM>. 0C be initiated.

The method involves controlling <NUM>, by the first and/or second HADs, charging of the HAD power sources at the accelerated charge rate. The method further involves communicating <NUM> charging data from the first and/or second HADs to the charging unit during accelerated charging of the HAD power sources. The method also involves transmitting <NUM>, in response to the SoC exceeding the predetermined SoC range, a termination signal from the charging unit to the first and/or second HADs requesting that accelerated charging be terminated. After termination of accelerated charging, the method involves removing the first and/or second HADs from the charging unit or proceeding with normal charging of the HAD power sources at a normal charge rate at or below <NUM>. 0C until fully charged.

<FIG> is a graph that characterizes accelerated charging of a lithium-ion battery in accordance with various embodiments. The graph of <FIG> characterizes battery voltage <NUM> and charge current <NUM> as a function of time during different phases of a charging procedure. As is indicated below the time axis, the different phases of the charging procedure include a pre-charge phase (A), an accelerated constant current charge phase (B), a constant voltage charge phase (D), and a charge complete phase (E). During the pre-charge phase (A), the charge current <NUM> is low (e.g., <NUM>. 1C) and the battery voltage <NUM> slowly increases. It is noted that a well-designed system should stay out of this regime. The pre-charge phase (A) continues until the battery voltage <NUM> reaches <NUM> V, at which time the accelerated constant current charge phase (B) is initiated.

During the accelerated charging phase (B), the charge current <NUM> rapidly increases to a charge rate above <NUM>. 0C, such as <NUM>. During the accelerated charging phase (B), high current is supplied to the battery which results in a rapid increase in battery voltage <NUM>. For example, a charge current of <NUM> mA can be supplied to the battery during the latter part of the pre-charge phase (A) (e.g., at <NUM>. The charge current can be increased to between <NUM> and <NUM> mA during the accelerated charging phase (B). The accelerated charging phase (B) continues until a predetermined time limit (e.g., <NUM>-<NUM>) has been reached. In some embodiments, the accelerated charging phase (B) continues until a predetermined battery voltage <NUM> (e.g., <NUM> V) or predetermined energy level (e.g., <NUM> mAh) has been reached.

At the conclusion of the accelerated charging phase (B), the charge current <NUM> rapidly decreases to a normal charge current level (e.g., <NUM> mA at a charge rate of <NUM>. 3C) at the initiation of the constant current charge phase (C). During the constant current charge phase (C), a normal charge current (e.g., 5mA) is supplied to the battery resulting in a continued increase in the battery voltage <NUM>. When the battery voltage <NUM> reaches a predetermined level (e.g., <NUM> V), the charging procedure transitions from the constant current charge phase (C) to the constant voltage charge phase (D). During the constant voltage charge phase (D), the charge current <NUM> decreases until a cutoff <NUM> is reached, at which time the charging procedure is terminated. It is noted that at the charging complete phase (E), the battery voltage <NUM> slightly drops over time (e.g., from <NUM> V to <NUM> V).

In the embodiment shown in the <FIG>, the charge current <NUM> supplied during the accelerated charging phase (B) changes in a step-wise fashion. It is understood that, in some embodiments, the charge current <NUM> can decrease gradually as the accelerated charging phase (B) transitions to the constant current charge phase (C).

Referring now to <FIG>, there is illustrated a block diagram of a portable rechargeable charging unit <NUM> in accordance with various embodiments. The portable charging unit <NUM> includes a power switch <NUM> which is configured to couple to a hardwired connector <NUM> (e.g., USB connector) or a wireless power source <NUM> (e.g., a Qi compliant wireless power source). The power switch <NUM> includes logic configured to select a power source (<NUM> or <NUM>) that provides the most power. The power switch <NUM> is coupled to a charger controller (microcontroller unit or MCU) <NUM> by control line <NUM>, and informs the charger controller <NUM> which power source has been selected. The power switch <NUM> is also coupled to a power management IC (PMIC) <NUM>. In some embodiments, the PMIC <NUM> is a USB-friendly Li-ion battery charger and power-path management IC, such as BQ24079T available from Texas Instruments. The PMIC <NUM> is configured to manage charging of the battery <NUM> and to supply power to other circuitry via the voltage regulator <NUM>. The voltage regulator <NUM> provides a stable voltage (e.g., <NUM> V) for other components of the portable charging unit <NUM>. The PMIC <NUM> communicates charging status information to the charger controller <NUM> via charging control line <NUM>.

The rechargeable battery <NUM> includes a temperature sensor <NUM> which is coupled to the PMIC <NUM>. The PMIC <NUM> determines whether charging of the battery <NUM> can be initiated based on the temperature of the battery <NUM>. For example, the PMIC <NUM> can initiate charging of the battery <NUM> when the battery temperature is within a temperature range of <NUM> to <NUM>° C. The battery <NUM> can have a capacity ranging from <NUM> mAh to <NUM> mAh, such as <NUM> mAh.

In some embodiments, the charger controller <NUM> is coupled to a magnetic reset switch <NUM>. The magnetic reset switched <NUM> can magnetically interact with a magnet arrangement of a hearing assistance device to initiate a system (hardware) rebooting of the device, if needed or desired. The charger controller <NUM> is also coupled to an accelerometer <NUM> via a serial communication bus and an interrupt line. As was discussed previously, the accelerometer <NUM> is responsive to a tap sequence applied by a user to the housing of the portable charging unit <NUM>. In response to a tap sequence (e.g., single, double, triple tap), the accelerometer <NUM> sends a signal to the charger controller <NUM> via the interrupt line. For example, a single tap can cause accelerometer <NUM> to communicate an accelerated charging request signal to the charger controller <NUM>. A double tap can cause accelerometer <NUM> to communicate an accelerated charging termination signal to the charger controller <NUM>.

By way of further example, a single tap can cause accelerometer <NUM> to communicate a user interface enable signal to the charger controller <NUM>, causing the user interface <NUM> to become active (turn on/illuminate). A double tap can cause accelerometer <NUM> to communicate a HAD battery status signal to the charger controller <NUM>, in which case the charge state of the HAD power sources can be indicated by the user interface <NUM>. For example, an SoC percentage for each HAD power source can be presented on a display or a colored LED can be illuminated, such as green (good), yellow (fair), or red (poor) indicating different charges states. A triple tap can cause the accelerometer <NUM> to communicate a charging unit battery status signal to the charger controller <NUM>, in which case the charge state of the charging unit battery <NUM> is indicated by the user interface <NUM>. The user interface <NUM> can include one or more of LEDs, an OLED display, an LCD, and E-INK display, a touchscreen, capacitive touch switches or other user input device(s).

The charger controller <NUM> is also coupled to a voltage boost converter <NUM>. The charger controller <NUM> decides whether or not to enable the voltage boost converter <NUM>, which provides a higher voltage to the HADs for charging. For example, the voltage boost converter <NUM> provides <NUM> V to the adjustable voltage regulators <NUM>, <NUM> of the left and right charge ports when the voltage regulators <NUM>, <NUM> are enabled (via enable lines) for charging by the charger controller <NUM>. If neither of the HADs are inserted in the charge ports of the portable charging unit <NUM>, the voltage boost converter <NUM> is not enabled by the charger controller <NUM>. As will be described hereinbelow, the enable lines of the charger controller <NUM> can be coupled to touch current mitigation circuitry to prevent the possibility of electrical currents flowing out of the exposed electrical contacts of the charge ports.

The charger controller <NUM> communicates with the left and right HADs via a transmit (Tx) communication line and a receive (Rx) communication line provided between the charger controller <NUM> and the adjustable voltage regulators <NUM>, <NUM>. In general terms, the charger controller <NUM> transmits a modulated voltage signal to communicate with the left and right HADs, and the left and right HADs transmit a modulated current signal to communicate with the charger controller <NUM>. The charger controller <NUM> communicates a signal via the Tx communication line causing the adjustable voltage regulators <NUM>, <NUM> to communicate a modulated voltage signal (e.g., a <NUM> V to <NUM> V square wave) to the left and right HADs. The charger controller <NUM> uses the Rx communication line coupled to current-to-voltage circuits <NUM>, <NUM><NUM> to receive a current signal and any current pulses generated by the left and right HADs. Using the Rx communication line, the charger controller <NUM> senses the amount of current the left and right HADs are drawing during charging, and any information signals communicated by the left and right HADs in the form of current pulses.

<FIG> is a block diagram of a hearing assistance device <NUM> configured to communicate with the portable charging unit <NUM> shown in <FIG> in accordance with various embodiments. The hearing assistance device <NUM> can represent the left or the right HAD. The hearing assistance device <NUM> includes a pair of charging contacts <NUM> configured to electrically connect with a pair of charging contacts within the charge port of the portable charging unit <NUM>. The charging contacts <NUM> are coupled to a power management IC (PMIC) <NUM>, which includes a temperature sensor <NUM>. A suitable PMIC is the HPM10 Power Management IC available from ON Semiconductor. The PMIC <NUM> is configured to generate the voltage needed by the HAD <NUM> and manages the charging algorithms implemented for charging the battery <NUM>, including accelerated charging. The PMIC <NUM> includes a charger communication interface to inform the portable charging unit <NUM> about the charging progress. Various types of battery information, such as voltage levels, current levels, temperature, and different types of battery failures, can also be communicated to the portable charging unit <NUM>. As was discussed previously, the portable charging unit <NUM> communicates with the PMIC <NUM> via a modulated voltage signal communicated through the charging contacts <NUM>. The PMIC <NUM> communicates with the portable charging unit <NUM> via a modulated current signal transmitted through the charging contacts <NUM>.

The battery <NUM> can be a lithium-ion battery with a capacity ranging from about <NUM> mAh to <NUM> mAh. In some larger hearables, the battery <NUM> can have a capacity of up to about <NUM> mAh.

The PMIC <NUM> is coupled to a digital signal processor (DSP) <NUM>. The PMIC <NUM> and the DSP <NUM> communicate via power control lines <NUM>. For example, the PMIC <NUM> can inform the DSP <NUM> when the charge state of the battery <NUM> is getting low. The DSP <NUM> can inform that PMIC <NUM> to power down in response to a switch input from the user. The DSP <NUM> is coupled to one or more microphones <NUM> (optional), a speaker or receiver <NUM>, and a wireless communication device <NUM> (e.g., a BLE device).

When the HAD <NUM> is inserted into a charge port of the portable charging unit <NUM>, the PMIC <NUM> instructs the DSP <NUM> to power down during the charging process. The adjustable voltage regulator <NUM> or <NUM> of the portable charging unit <NUM> provides <NUM> V at the charging contacts <NUM> of the HAD <NUM>. The PMIC <NUM> controls the different phases of a charging procedure when charging the battery <NUM>. For example, and with reference to <FIG>, the PMIC <NUM> controls charging of the battery <NUM> during the pre-charge phase (A), the accelerated constant current charge phase (B), the constant current charge phase (C), the constant voltage charge phase (D), and the charging complete phase (E). After completion of the charging procedure, and removal of the HAD <NUM> from the charge port, the PMIC <NUM> instructs the DSP <NUM> to power up, since the HAD <NUM> is no longer in a charging mode. The PMIC <NUM> will remain powered off if charging of the HAD <NUM> is complete but the HAD <NUM> remains in the charge port.

The following are different charging scenarios for purposes of illustration. After a normal day of use, the left and right HADs <NUM> are inserted into the charge ports of the portable charging unit <NUM>. The PMIC <NUM> of the portable charging unit <NUM> determines the state of charge of the battery <NUM> of the left and right HADs <NUM>. Since the battery <NUM> is not depleted after a normal day of use, accelerated charging is not indicated. As such, the portable charging unit <NUM> provides <NUM> V at the charging contacts <NUM> of the left and right HADs <NUM>, and the PMIC <NUM> of the left and right HADs <NUM> implements normal charging of the battery <NUM> (e.g., charging phases C, D, and E). During the charging procedure, the PMIC <NUM> reports charging information back to the charger controller <NUM> every <NUM> seconds. For example, the charging information can include the voltage across the battery <NUM>, the amount of current into the battery <NUM>, and the amount of energy into the battery <NUM>.

If, however, the left and right HADs <NUM> were heavily used during the day (e.g., long periods of audio streaming), the battery <NUM> of the left and right HADs <NUM> may be nearly or completely depleted. After inserting the left and right HADs <NUM> into the charge ports of the portable charging unit <NUM>, the charger controller <NUM> of the portable charging unit <NUM> receives battery status of the left and right HADs <NUM> from the PMIC <NUM>. For example, the battery status information may indicate that the voltage across the battery <NUM> is <NUM> V or that the SoC is between <NUM> and <NUM>%. In response, the charger controller <NUM> sends a packet to the PMIC <NUM> of the left and right HADs requesting that the PMIC <NUM> implement accelerated constant current charging (e.g., charging phase B). For example, the packet can instruct the PMIC <NUM> to increase the charge current from <NUM> mA to <NUM> or <NUM> mA (e.g., <NUM>-3C). During the accelerated charging phase, the PMIC <NUM> reports charging information back to the charger controller <NUM> every <NUM> seconds.

The charger controller <NUM> determines when accelerated charging should be terminated, such as by expiration of a predetermined time limit (e.g., <NUM>, <NUM> or <NUM> minutes), reaching a predetermined voltage on the battery <NUM> (e.g., <NUM>. 1V), or reaching a predetermined energy level on the battery <NUM> (e.g., <NUM> mAh). The charger controller <NUM> sends a packet to the PMIC <NUM> of the left and right HADs to reduce the charge current to <NUM> mA (e.g., at <NUM>. 3C) in a constant current mode. After completion of the accelerated charging phase, the left and right HADs <NUM> can be removed from the portable charging unit <NUM> for immediate use. Alternatively, normal charging of the battery <NUM> (e.g., charging phases C, D, and E) can be implemented by the PMIC <NUM> until the battery <NUM> is fully charged.

According to some embodiments, a portable charging unit can incorporate touch current mitigation circuitry to prevent the possibility of electrical currents flowing out of the exposed electrical contacts of the charge ports. For example, the touch current mitigation circuitry prevents electrical current flow between charge ports when a user places a finger of their left hand in a first charge port and a finger of their right hand in a second charge port. To meet a medical device regulation (e.g., IEC <NUM>-<NUM>-<NUM>), for example, the current can never go above <NUM>µA across a <NUM> Ohm load. This means that any exposed electrical contacts with more than <NUM> V will not meet this regulation. Charging batteries via contact charging usually requires much greater voltages.

A charger designed for charging two or more hearing assistance devices includes multiple points of electrical contact between power and ground. For either of the devices, the set of power and ground pins should be designed such that two probes, as per medical regulation IEC <NUM>-<NUM>-<NUM>, cannot establish a path between power and ground using both probes. Given the dimensions of the hearing assistance devices charged by the portable charging unit, it may be difficult or impossible to design the electrical contacts such that one probe cannot contact any of the electrical contacts. Touch current mitigation circuitry, such as that illustrated in <FIG>, prevents currents from flowing through unintended paths between the multiple power and ground electrical contacts.

According to various embodiments, the touch current mitigation circuitry shown in <FIG> comprises solid state switches on the power and ground electrical contacts. These switches can be simple MOSFETS (PMOS for the power contacts, and NMOS for the ground contacts), bilateral CMOS, programmable load switches, mechanical disconnects such as relays, or other solid state switch technologies. The switch enable lines are connected to a form of logic to only activate the switches when the exposed electrical contacts of the portable charging unit are connected to the electrical contacts of the hearing assistance devices.

<FIG> shows a first charge port <NUM> and a second charge port <NUM> of a portable charging unit. The first charge port <NUM> includes a first exposed contact <NUM> coupled to a <NUM> V source via switch SW1, and a second exposed contact <NUM> coupled to ground (GND) via switch SW2. The second charge port <NUM> includes a first exposed contact <NUM> coupled to a <NUM> V source via switch SW3, and a second exposed contact <NUM> coupled to ground via switch SW <NUM>. Switches SW1 and SW2 are controlled by a first enable line EN1, and switches SW3 and SW4 are controlled by a second enable line EN2. The first and second enable lines EN1 and EN2 of <FIG> can correspond to first and second enable lines of the charger controller <NUM> shown in <FIG>. As is shown in <FIG>, the first enable line EN1 enables the adjustable voltage regulator <NUM> and the current-to-voltage circuitry <NUM>. The second enable line EN2 enables the adjustable voltage regulator <NUM> and the current-to-voltage circuitry <NUM>.

When EN1 is activated, switches SW1 and SW2 close and allow current to flow in or out of the exposed electrical contacts <NUM> (5Va) or <NUM> (0Va). When enable line EN1 is deactivated, switches SW1 and SW2 are opened and no current can flow into or out of either contact <NUM> or <NUM>. When enable line EN2 is activated, switches SW3 and SW4 close and allow current to flow in or out of the exposed electrical contacts <NUM> (5Vb) or <NUM> (0Vb). When enable line EN2 is deactivated, switches SW3 and SW4 are opened and no current can flow into or out of either contact <NUM> or <NUM>. This arrangement allows for four possible states given in Table <NUM> below.

It is noted that Table <NUM> above can be extended to N number of contacts. With N contacts, there will be two switches per contact as in <FIG>, making for 2N switches in the system. This will mean 2N states where each state is a unique combination of switch states.

In order for the system to know when it is possible to enable current flow, the following steps are provided as an example sequence. First, both enable lines EN1 and EN2 start in a deactivated state. Second, only EN1 is initially activated to allow current to flow. This will charge the HAD and provide a signal that the charger controller <NUM> monitors to detect whether the HAD is present using a characteristic current or communication on the line. For example, the charger controller <NUM> can look for a characteristic current profile that is present when a HAD is connected to a charge port. This process should take less than <NUM>/N the period required to check N contacts to prevent user exposure. This rate is guided by human reaction time to provide a desirable user experience. Third, if the logic implemented by the charger controller <NUM> does not find an intended HAD, it will deactivate the activated circuit (e.g., EN1) and activate the other circuit (e.g., EN2) after the contacts controlled by EN1 are de-energized. A delay can be used to insure the switches SW1 and SW2 are fully de-energized before activating EN2. Fourth, the logic implemented by the charger controller <NUM> will then do the same analysis to decide if an intended HAD is connected to the exposed electrical contacts controlled by EN2. If the logic does not find a HAD, it will deactivate the active circuit (e.g., EN2) and optionally sleep before repeating the process. By allowing the electrical circuits to enter a sleep state for a small delay (e.g., <NUM>), the circuit can reduce current consumption by trading off time to detect a HAD after placement (e.g., <NUM> + time required to detect a HAD). Fifth, the logic implemented by the charger controller <NUM> will then do the same analysis to decide if an intended HAD is connected to the exposed electrical contacts controlled by EN3 and so on according to the total number of contacts N. Once a HAD is detected, the charger controller <NUM> will continually check for the signal evidencing that the HAD is present. If this signal is not detected, the associated charging contacts are disabled as soon as possible to prevent a state where the contacts may be exposed once more.

It is noted that a conventional approach to mitigating touch current involves recessing the contact pins such that it is mechanically impossible to touch the contact pins. Other conventional approaches include a cover with some form of switch that disconnects the pins either electrically or mechanically when the cover is open. Recessing contact pins introduces a risk of material clogging up the recessed hole and not allowing the electrical connection to connect. For a very low profile design, a cover is not ideal, and the added circuitry and mechanical parts for a switch increase the cost. When a switch is used to charge only when the cover is closed, this prevents the device from charging while open.

The touch current mitigation circuitry illustrated in <FIG> allows for any mechanical design with no limitations for the charging contacts in a medical setting. The touch current mitigation circuitry uses a small number of small solid state switches which can be very inexpensive and minimally increase the size of the circuitry. When the touch current mitigation circuitry looks for a signal proving the presence of an acceptable HAD to charge, the circuitry verifies that a proper HAD has been inserted before continuing to apply power. The touch current mitigation circuitry provides for a coverless charger design and removes any circuitry from detecting a closed cover. This results in saving power, as the circuitry can duty cycle the charging contacts to detect a proper device. When an improper device is detected, power is saved by terminating current flow.

<FIG> illustrate a tether cable arrangement <NUM> between a portable rechargeable charging unit <NUM> and a pair of hearing assistance devices <NUM>, <NUM> in accordance with various embodiments. In some embodiments, the tether cable arrangement <NUM> facilitates concurrent powering and charging of the HADs <NUM>, <NUM> when the HADs <NUM>, <NUM> run out of power during daily use. In other embodiments, the tether cable arrangement <NUM> facilitates powering, but not charging, of the HADs <NUM>, <NUM>.

The tether cable arrangement <NUM> includes a charging unit connector <NUM> configured to electrically coupled to the interface of the portable charging unit <NUM> (see, e.g., interface <NUM> in <FIG>). The charging unit connector <NUM> is electrically connected to a first cable <NUM> and a second cable <NUM>. A first HAD connector <NUM> is connected at the end of the first cable <NUM>, and a second HAD connector <NUM> is connected at the end of the second cable <NUM>. The first and second HAD connectors <NUM>, <NUM> are configured in a manner similar to the charge ports of the portable charge unit <NUM>.

The first HAD connector <NUM> includes a pair of electrical contacts that establish a connection with a corresponding pair of electrical contacts of a first HAD <NUM>. The first HAD connector <NUM> includes a magnet that magnetically interacts with a magnet or ferrous material of the first HAD <NUM>, which serves to maintain mating engagement between the first HAD connector <NUM> and the first HAD <NUM> during use. The second HAD connector <NUM> includes a pair of electrical contacts that establish a connection with a corresponding pair of electrical contact of a second HAD <NUM>. The second HAD connector <NUM> includes a magnet that magnetically interacts with a magnet or ferrous material of the second HAD <NUM>, which serves to maintain mating engagement between the second HAD connector <NUM> and the second HAD <NUM> during use.

Advantageously, the first and second HADs <NUM>, <NUM> remain active and can be used while the tether cable connection facilitates charging of the power sources of the first and second HADs <NUM>, <NUM>. According to some embodiments, after <NUM> minutes of powering/charging via the tether cable arrangement, the power sources of the first and second HADs <NUM>, <NUM> have over <NUM>-½ hours of capacity. After one hour of tethered powering/charging, the power sources of the first and second HADs <NUM>, <NUM> have greater than <NUM> hours of capacity. Accelerated charging is available using the tether cable arrangement, but typically at a lower charge rate (e.g., <NUM>. 5C - <NUM>.

In other embodiments, the HADs <NUM>, <NUM> may be of a size too small to contain a rechargeable battery. Instead, the HADs <NUM>, <NUM> may include a small non-rechargeable battery. In such embodiments, the portable charging unit <NUM> can be attached to the HADs <NUM>, <NUM> via the tether cable arrangement <NUM> to supply power to the HADs <NUM>, <NUM> without depleting the non-rechargeable battery. For example, the portable charging unit <NUM> can supply power needed to stream audio through the HADs <NUM>, <NUM> (e.g., while watching a movie) without drawing power from the non-rechargeable battery.

According to some embodiments, the portable charging unit can cooperate with a pair of hearing assistance devices to provide a portable microphone capability. Referring again to <FIG>, the user interface <NUM> of the portable charging unit <NUM> can be used to actuate a portable microphone function of the portable charging unit <NUM>. For example, a sequence of <NUM> taps to the housing of the portable charging unit <NUM> can be detected by the accelerometer <NUM>, which in turn activates the portable microphone function. The user places one of the HADs (e.g., HAD <NUM>) in a charge port (e.g., charge port <NUM>), while the other HAD (e.g., HAD <NUM>) is worn by the user. When connected, the portable charging unit <NUM> instructs HAD <NUM> to turn off its speaker/receiver, while leaving the microphone and wireless communication device active. The active microphone and wireless communication device of HAD <NUM> allows for transmission of audio proximate the portable charging unit <NUM> to be communicated to the still worn HAD <NUM>. The portable charging unit <NUM> can be moved to any desired location, allowing the wearer to receive audio from such location. The portable microphone function can be terminated by an appropriate user input to the user interface <NUM> (e.g., a double tap to the housing of the portable charging unit <NUM>).

In other embodiments, the portable charging unit <NUM> includes a microphone <NUM> and a wireless communication device <NUM> (e.g., a BLE device) which provide a portable microphone capability. With reference again to <FIG>, a microphone <NUM> can be mounted on the housing of the portable charging unit <NUM>. A tap sequence (e.g., <NUM> taps) can be applied to the housing of the portable charging unit <NUM> and detected by the accelerometer <NUM>, which activates the portable microphone function using the microphone <NUM>. In this embodiment, the user need not remove one of the HADs <NUM>, <NUM> to implement the portable microphone function. The microphone <NUM>, communication device <NUM>, and wireless communication devices of the HADs <NUM>, <NUM> cooperate to transmit audio received by the microphone <NUM> to the HADs <NUM>, <NUM>.

Claim 1:
A system comprising:
first and second hearing assistance devices (<NUM>, <NUM>, <NUM>, <NUM>) each comprising a rechargeable lithium-ion power source and power management circuitry (<NUM>, <NUM>) configured to control charging of the power sources; and
a portable charging unit (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) comprising:
an interface configured to receive a connector of a power cable or a power and data cable;
a rechargeable lithium-ion power source coupled to the interface;
first and second charge ports (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) configured to receive the first and second hearing assistance devices (<NUM>, <NUM>, <NUM>, <NUM>), and
charging circuitry (<NUM>) coupled to the first and second charge ports (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>) and to the rechargeable power source of the charging unit;
wherein the power management circuitry (<NUM>, <NUM>) and the charging circuitry (<NUM>) are configured to cooperate to fully charge the power sources of the hearing assistance devices (<NUM>, <NUM>, <NUM>, <NUM>) at a charge rate at or below <NUM>.0C when a state of charge, SoC, of the power sources is outside a predetermined SoC range, and
wherein the power management circuitry (<NUM>, <NUM>) and the charging circuitry (<NUM>) are configured to cooperate to partially charge the power sources of the hearing assistance devices (<NUM>, <NUM>, <NUM>, <NUM>) at an accelerated charge rate above <NUM>.0C when the SoC of the power sources is within the predetermined SoC range, and the predetermined SoC range is a range from a fully discharged state to about <NUM>%
wherein charging at the accelerated charge rate is terminated in response to reaching a predetermined time limit.