Abstract:
A proximity detection apparatus including a detection circuit is provided. The detection circuit is configured to receive a proximity signal indicative of a first voltage level and a reference signal indicative of a second voltage level and to receive a wake up signal at predetermined intervals. The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to generate a first output indicative of an external power source being electrically coupled to a vehicle to charge one or more batteries in the vehicle based on the comparison of the first voltage level to the second voltage level.

Description:
TECHNICAL FIELD 
       [0001]    Aspects of the present disclosure provide a low power proximity circuit (or apparatus) in connection with various battery charging applications. 
       BACKGROUND 
       [0002]    U.S. Pat. No. 8,305,033 (“the &#39;033 patent”) to Cavanaugh discloses a proximity detection circuit suitable for use with an on-board vehicle charger, such as but not limited to the type of charges used within hybrid and hybrid electric vehicles, to facilitate current conservation during a period of time when it is unnecessary or otherwise undesirable for the on-board charger to test for connection of a cordset or other connection used to connect the on-board charger to a charging station or other current source. 
       SUMMARY 
       [0003]    A proximity detection apparatus including a detection circuit is provided. The detection circuit is configured to receive a proximity signal indicative of a first voltage level and a reference signal indicative of a second voltage level and to receive a wake up signal at predetermined intervals. The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to generate a first output indicative of an external power source being electrically coupled to a vehicle to charge one or more batteries in the vehicle based on the comparison of the first voltage level to the second voltage level. 
         [0004]    A proximity detection apparatus including an event storage circuit and a detection circuit is provided. The event storage circuit is configured to indicate that an external power source is coupled to a vehicle. The detection circuit is configured to receive a proximity signal indicative of a first voltage level and a reference signal indicative of a second voltage level and to receive a wake up signal at predetermined intervals. The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to provide a first output indicative of the external power source being electrically coupled to the vehicle to charge one or more batteries in the vehicle to the event storage circuit in response to comparing the first voltage level to the second voltage level. 
         [0005]    A proximity detection apparatus including a flip-flop circuit and a detection circuit is provided. The detection circuit is configured to receive a proximity signal indicative of a first voltage level and a reference signal indicative of a second voltage level to receive a wake up signal at predetermined intervals. The detection circuit is further configured to compare the first voltage level to the second voltage level in response to the wake up signal and to provide a first output indicative of the external power source being electrically coupled to the vehicle to charge one or more batteries in the vehicle to the flip-flop circuit in response to comparing the first voltage level to the second voltage level. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The embodiments of the present disclosure are pointed out with particularity in the appended claims. However, other features of the various embodiments will become more apparent and will be best understood by referring to the following detailed description in conjunction with the accompany drawings in which: 
           [0007]      FIG. 1  depicts an apparatus for providing low power proximity detection in accordance to one embodiment; 
           [0008]      FIG. 2  depicts a plot of various waveforms corresponding to various signal inputs to an event storage circuit in accordance to one embodiment; 
           [0009]      FIG. 3  depicts a plot of a waveform that generates a wake up event for a microcontroller in accordance to one embodiment; and 
           [0010]      FIG. 4  depicts a plot of various waveforms that are provided to the apparatus in accordance to one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. The embodiments of the present disclosure generally provide for a plurality of circuits, electrical devices, and at least one controller. All references to the circuits, the at least one controller, and other electrical devices and the functionality provided by each, are not intended to be limited to encompassing only what is illustrated and described herein. While particular labels may be assigned to the various circuit(s), controller(s) and other electrical devices disclosed, such labels are not intended to limit the scope of operation for the various circuit(s), controller(s) and other electrical devices. Such circuit(s), controller(s) and other electrical devices may be combined with each other and/or separated in any manner based on the particular type of electrical implementation that is desired. 
         [0012]    It is recognized that any controller as disclosed herein may include any number of microprocessors, integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof), and software which co-act with one another to perform operation(s) disclosed herein. In addition, any controller as disclosed utilizes any one or more microprocessors to execute a computer-program that is embodied in a non-transitory computer readable medium that is programmed to perform any number of the functions as disclosed. Further, any controller as provided herein includes a housing and the various number of microprocessors, integrated circuits, and memory devices ((e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM)) positioned within the housing. The controller(s) as disclosed also include hardware based inputs and outputs for receiving and transmitting data, respectively from and to other hardware based devices as discussed herein. 
         [0013]    Proximity detection circuits detect the presence of cordset when plugged into a vehicle (and to an external power supply) to enable vehicle battery charging. Once the proximity detection circuit detects that a cordset is plugged to the vehicle, the proximity detection circuit generates an output to indicate to the vehicle that the vehicle may receive power from an alternating current power source at a residence, commercial establishment, or other charging system. In moments where the cordset is not plugged or operably connected to the vehicle to enable battery charging, it is necessary to power the proximity detection circuit intermittently so that the proximity detection circuit can monitor for the presence of the cordset when other controllers and electrical devices in the vehicle are in a sleep mode. Thus, this condition of powering the proximity detection circuit while the vehicle is in the sleep mode may draw large amounts of quiescent current and consume stored power on one or more batteries on the vehicle. Therefore, there may be a need to provide a low proximity detection circuit that detects the proximity or physical connection of the cordset to the energy power source and to the vehicle while maintaining a low quiescent current to mitigate power consumption of the battery in moments where the battery is not being charged. 
         [0014]      FIG. 1  depicts an apparatus  10  for providing low power proximity detection in a vehicle  12  in accordance to one embodiment. The apparatus  10  includes a detection circuit  14 , a hold circuit  16 , an event storage circuit  18 , and a pulse generator circuit  20 . A switch  22  is operably connected to the detection circuit  14 . The switch  22  provides a signal PROXIMITY that indicates whether a cordset  21  is coupled to the vehicle  12  and to an external power source  23  to the vehicle for charging one or more batteries  53  in the vehicle  12 . The cordset  21  may be portable or may be mounted proximate to an electrical outlet on or about an establishment for conditioning power from the electrical outlet and for providing the conditioned power one or more batteries  53  in the vehicle  12 . 
         [0015]    The detection circuit  14  includes a plurality of resistors  24   a - 24   n,  a comparator  26 , and at least one capacitor  28 . A signal WAKE_UP is provided to the detection circuit  14  for providing voltage at predetermined intervals. In general, the detection circuit  14  is not powered all of the time (or continuously) when the vehicle  12  is in the OFF state (e.g., vehicle ignition is OFF). In one example, the signal WAKE_UP is applied every 256 ms and may be applied for a period of 400 μs. This condition aids in reducing current draw at the apparatus  10  when the vehicle  12  is in the OFF state. The apparatus  10  may provide the signal WAKE_UP from a system basis chip (“SBC”) that includes an integrated timer and wake up strobing sensing capability. The SBC may be located in the apparatus  10  or may be positioned in an electronic vehicle controller in the vehicle  12 . 
         [0016]    When an operator connects the cordset  21  to the vehicle  12  and to the external power source  23  to the vehicle  12 , the switch  22  provides a low voltage on the signal PROXIMITY to the comparator  26 . The comparator  26 , when strobed with a high voltage on the signal WAKE_UP (e.g., power is applied at the predetermined interval when the vehicle  12  is in a sleep mode or in an awake mode), compares the low voltage (or voltage level) (see PIN  3  on comparator  26 ) to a reference voltage (or reference signal having another voltage level) (see PIN  4  on the comparator  26 ) as provided by a signal VREF_WAKE. The signal VREF_WAKE is derived from the signal WAKE_UP and is arranged at a different voltage level than the signal WAKE_UP. A voltage divider (not shown) is arranged to provide the signal VREF_WAKE at a voltage that is different than the signal WAKE_UP. If the comparator  26  determines that the low voltage is less than the reference voltage, then the comparator  26  outputs a high output (e.g., 5V). A pin output  30  of the detection circuit  14  provides the high output to the hold circuit  16 . 
         [0017]    When the operator disconnects the cordset  21  to the vehicle  12  and/or to the external power source  23  to the vehicle  12 , the switch  22  provides a high signal on the signal PROXIMITY to the comparator  26 . The comparator  26 , when strobed with a high voltage on the signal WAKE_UP (e.g., power is applied at the predetermined interval which reduces quiescent current), compares the high voltage (see PIN  3  on the comparator  26 ) to the reference voltage (see PIN  4  on the comparator  26 ) as provided by the signal VREF_WAKE. If the comparator  26  determines that the high voltage is greater than the reference voltage, then the comparator  26  outputs a low output (e.g., 0V). The pin output  30  of the detection circuit  14  provides the low output to the hold circuit  16 . In general, the moment in which the cordset  21  is connected to the vehicle  12  and to the external power source  23 , the switch  22  transitions to provide a low output and the detection circuit  14  transitions to provide a high output. The moment in which the cordset is disconnected from the vehicle and/or the external power source, the switch  22  transitions to provide a high output and the detection circuit  14  transitions to provide a low output. 
         [0018]    The hold circuit  16  includes a diode circuit  32 . In one example, the diode circuit  32  may be a Schottky diode. The event storage circuit  18  includes a flip-flop circuit  34 , resistors  36   a - 36   n,  capacitors  38   a - 38   n,  and a diode circuit  40 . In one example, the flip-flop circuit  34  may be a D flip-flop. The hold circuit  16  is configured to hold the output received from the detection circuit  14  for a period of time to enable the flip-flop circuit  34  to receive a high voltage on the WAKE_UP to wake up the flip-flop circuit  34  so that the flip-flop circuit  34  receives the output from the detection circuit  14 . An input (or clock signal) is provided to the flip-flop circuit  34  (e.g., at input  1  (or CLK) of the flip-flop circuit  34 ) to detect the state of input “D.” The diode circuit  40  ensures that a sharp fall time and a slow rise time for the clock signal that is provided to input  1  of the flip-flop circuit  34 . Because the clock signal may be slow, the flip-flop circuit  34  may be susceptible to re-sampling on a falling edge of the clock signal (i.e., for a rising edge triggered flip-flop circuit  34 ). 
         [0019]    In general, the clock signal data (e.g., the data received from the pin output  30  and the hold circuit  16  at the flip-flop circuit  34  (as received at input “D”) in on a rising edge. The hold circuit  16  ensures that the data provided to the input D at the flip-flop circuit  34  is present before the rising edge of the clock signal arrives at the input CLK at the flip-flop circuit  34  and further ensures that the data provided to the input D is valid after the clock signal transitions low. For example, the hold circuit  16  stores the output from the detection circuit  14  for a period of time to ensure that the event storage circuit  18 , upon wake up, is capable of receiving (or detecting) the output from the detection circuit  14  upon either the switch  22  being disconnected (e.g., no vehicle charging being performed) or the switch  22  being connected (e.g., vehicle charging being performed). For example, the hold circuit  16  sustains the state of information provided to an input “D” during both a rising edge and a falling edge of the clock signal to ensure that the flip-flop circuit  34  provides a valid output at “Q” of the flip-flop circuit  34 . In this case, the flip-flop circuit  34  retains the output from the detection circuit  14  and the flip-flop circuit  34  does not retrigger the same event. Because the flip-flop circuit  34  does not retrigger on the same event (i.e., the output, Q stays at the same level until the cordset  31  is disconnected), this condition lowers the quiescent current draw. 
         [0020]    The pulse generator circuit  20  includes a diode circuit  40 , a plurality of capacitors  42   a - 42   n,  and a resistor  44 . In one example, the diode circuit  40  may be a Schottky diode. The capacitor  42   a  (or bypass capacitor) of the pulse generator circuit  20  is operably coupled to an output of the flip-flop circuit  34  which enables the flip-flop circuit  34  to only consume current as the switch  22  transitions from either closed-to-open or open-to-closed. In general, as the output of the detection circuit  14  is fed to the hold circuit  16  and subsequently to the flip-flop circuit  34  at input “D”, the flip-flop circuit  34  then provides such an output (i.e., the state of the switch  22  or the proximity detection) to the capacitor  42   a  of the pulse generator circuit  20 . It should be recognized that capacitor  42   a  provides the output from the flip-flop circuit  34  as a single pulse to the diode circuit  40  and not at a constant level which therefore serves to minimize current consumption (or reduce quiescent current draw) for the event storage circuit  18 . The pulse generator circuit  20  provides an output on to one or more microprocessors  51  in the vehicle  12  that the vehicle  12  is being charged if the flip-flop circuit  34  provides a high output (or output, Q from the flip-flop circuit  34  is high). 
         [0021]    In general, the diode circuit  40  allows or enables a positive pulse generation. For example, when the flip-flop circuit  34  provides a low output, the remaining diode (i.e., the diode position on top of the diode circuit  40 ) discharges the capacitor  42   a.  The output from the diode circuit  40  is transmitted to an input IO_ 1  of the SBC (or to the other microprocessors  51 ) that provides periodic strobe synchronized sensing. The capacitor  42   n  is similar to the capacitor  42   a  in that the capacitor  42   n  provides an output (or is discharged) when the flip-flop circuit  34  provides a low output when the cordset  21  is disconnected. An inverting buffer  46  (or switch) is provided to invert a negative pulse into a positive pulse. 
         [0022]      FIG. 2  depicts a plot  120  of various waveforms corresponding to various signal inputs to the apparatus  10  and the corresponding impact to the event storage circuit in accordance to one embodiment. As shown, waveform  122  corresponds to signal PROXIMITY as provided from the switch  22  to the detection circuit  14 . Waveform  124  corresponds to a signal that is being provided to the flip-flop circuit  34  at input “D” of the event storage circuit  18 . Waveform  126  corresponds to a signal that is provided to input “CLK” (i.e., clock input or the clock signal) to the flip-flop circuit  34 . Waveform  128  corresponds to a signal that is provided from output “Q” at the flip-flop circuit  34 . 
         [0023]    As illustrated at point  140 , the switch  22  provides a transition from a rising edge to a falling edge. This condition corresponds to the case in which the cordset  21  is coupled to both the vehicle  12  and to the external power source  23  for charging one or more batteries  53  in the vehicle  12 . At point  142 , the output from the detection circuit  14  goes high (e.g., the comparator  26  outputs a high output) which is then fed to the input “D” of the flip-flop circuit  34 . For each pulse of the clock signal that goes high, the corresponding input that is provided the input “D” of the flip-flop circuit  34  is registered. As can be seen at waveform  128 , the output “Q” from the flip-flop circuit  34  goes high as soon as the signal PROXIMITY transitions from the rising edge to the falling edge. 
         [0024]      FIG. 3  depicts a plot  150  of waveforms that generates a wake up event for a microcontroller (not shown) in accordance to one embodiment. As shown, waveform  122  corresponds to signal PROXIMITY as provided from the switch  22  to the detection circuit  14 . In general, the apparatus  10  is capable of detecting a connection and disconnection of the cordset  21 . As such, either a rising or falling waveform can be used. Waveform  154 , for example, corresponds to a wakeup event at a microcontroller as the signal PROXIMITY transitions from the rising edge to the falling edge. As noted above, such a transition in this example corresponds to the switch  22  being closed which indicates that the cordset  21  has been connected to the vehicle  12  and to the external power source  23  for purposes of charging the vehicle  12 . 
         [0025]      FIG. 4  depicts a plot  200  of various waveforms that are provided to the apparatus  10  in accordance to one embodiment. As seen, the signal WAKE_UP is high at predetermined intervals to power (or strobe) various portions of the apparatus  10  to minimize current consumption. At point  202  on the signal PROXIMITY, a transition can be seen from a rising edge to a falling edge. This condition corresponds to a change in electrical resistance, or the switch  22  being toggled to reflect that the cordset  21  is electrically coupled to the vehicle  12  and to the external power source  23 . Point  204  corresponds to a point in time in which the wakeup event (i.e., the cordset  21  is connected to the vehicle  12  and to the external power source  23 ). The detection circuit  14  detects the event and provides a high output which is received at input “D” of the flip-flop circuit  34  at the next rising edge on the signal WAKE_UP. The flip-flop circuit  34  in turn outputs a rising edge on the output “Q” (see signal Q in  FIG. 6 ). The pulse generator circuit  20  provides a signal IO_ 1  including a voltage pulse for waking one or more microprocessors in the vehicle  12 . Once the proximity event is detected (i.e., the cordset  21  is connected to the vehicle  12  and to the external power source  23 ), the one or more microprocessors wake up the vehicle  12  (or other vehicle electronics) to initiate a charging session. 
         [0026]    As shown, the signal Q remains high until another wakeup event is detected (see point  206 ). Prior to point  206  on the plot  200 , it can be seen that the signal PROXIMITY transitions from a falling edge to a rising edge. This condition exhibits that the cordset  21  has been disconnected from the vehicle  12  and/or the external power source  23 . The switch  22  transmits the signal PROXIMITY that illustrates the above noted condition. The detection circuit  14  detects the event and provides a low output which is received at input “D” of the flip-flop circuit  34  at the next rising edge on the signal WAKE_UP. The flip-flop circuit  34  in turn outputs a falling edge on the output “Q” (see signal Q in  FIG. 6 ). The pulse generator circuit  20  provides the signal IO_ 1  including a voltage pulse for alerting the one or more microprocessors in the vehicle  12  that the vehicle is no longer being charged. 
         [0027]    While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.