Abstract:
A modular power adapter and method for using the same which increases the ease of a user&#39;s travel with portable electronic devices. The modular power adapter includes an output module which may be interchangeably and detachably coupled to DC input module or an AC input module. The output module and the input module are provided in separate housing structures thereby effectively spreading the heat dissipated from the modular power adapter.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    Embodiments of the present invention relate to a power adapter device and method for using the same. More specifically, the invention relates to a light weight, modular power adapter having a common module which connects to an electronic device and alternative modules which connect to the common module, depending on whether the source of power is AC or DC. 
         [0003]    2. Description of Related Art 
         [0004]    The popularity of portable electronic devices has grown exponentially. These portable electronic devices include laptop computers, handheld devices such as personal digital assistants (PDA), cellular telephones, digital cameras, audio recorders, Compact Disc (CD) players, MP3 players and portable digital video disc (DVD) players. Consumers often use such portable electronic devices at home, as well as in their cars, on airplanes, and at various travel destinations. While consumers are increasingly using such devices while in transit from one location to another, power constraints remain a limiting factor. Although, many of these devices are configured to operate using a battery source, often the battery life is insufficient and makes use of the device while in transit impractical. 
         [0005]    On the other hand, conventional power adapters which support such use are bulky, heavy and cumbersome. In addition, conventional power adapters also frequently operate at high temperatures which results in a reduced life cycle for the adapters and increased expense associated with replacement costs. 
         [0006]    Conventional power adapters are typically powered by AC only or on DC only. Accordingly, there is a need for a modular power adapter which works in both an AC mode and a DC mode. Further, there is a need for a modular power adapter, which is lightweight, less cumbersome, environmentally-friendly and has a lower operating temperature. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a modular power adapter for providing a consumer- and environmentally-friendly connection between power source and portable electronics devices. It is an object of the present invention to improve the portability of electronics devices by modularizing the power adapter thereby reducing the weight of the adapter that must be carried. Another object of the invention is to distribute the heat dissipated by the modular power adapter, thus improving the lifespan of the power adapter when compared to conventional power adapters. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIGS. 1A and 1B  are block diagrams of a modular power adapter according to an embodiment of the present invention. 
           [0009]      FIG. 2A  is a perspective view of a modular power adapter configured in a DC mode according to an embodiment of the present invention. 
           [0010]      FIG. 2B  is a perspective view of a modular power adapter configured in a AC mode according to an embodiment of the present invention. 
           [0011]      FIG. 3  is a perspective view of an AC input module of a modular power adapter according to an embodiment of the present invention. 
           [0012]      FIG. 4  is a block diagram of a DC input module of the modular power adapter according to an embodiment of the present invention. 
           [0013]      FIG. 5  is a block diagram of an AC input module of a modular power adapter according to an embodiment of the present invention. 
           [0014]      FIG. 6  is a block diagram of a DC Output Module of the modular power adapter according to an embodiment of the present invention. 
           [0015]      FIG. 7  is a schematic diagram of the a DC input module of the modular power adapter according to an embodiment of the present invention. 
           [0016]      FIG. 8  is a schematic diagram of the a AC input module of the modular power adapter according to an embodiment of the present invention. 
           [0017]      FIG. 9  is a schematic diagram of the a DC output module of the modular power adapter according to an embodiment of the present invention. 
           [0018]      FIG. 10  is a flow diagram illustrating a method for providing a modular power connection according to an embodiment of the present invention. 
           [0019]      FIG. 11  is a flow diagram illustrating a method for providing a modular power connection according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]      FIG. 1A  is a block diagram of a modular power adapter according to an embodiment of the present invention. As shown in  FIG. 1A , modular power adapter  100  is configured in an DC mode and includes a DC input module  110 . The modular power adapter  100  also includes a DC output module  120 . The DC input module  110  may be configured with interface connectors (not shown) so as to be detachable from the DC power source  130  and also from the DC output module  120 . The DC input module  110  receives DC power from DC power source  130  which may be a cigarette lighter socket, an airline in-seat adapter, an external battery or the like. The DC input module  110  generates a regulated DC voltage and provides the regulated DC voltage to the DC output module  120 . The DC output module  120  may be detachably coupled to a portable electronic device portable electronic device  140  such as a laptop computer, a handheld device such as personal digital assistant (PDA), a cellular telephone, a digital camera, an audio recorder, a Compact Disc (CD) player, an MP3 player or a portable digital video disc (DVD) player. The DC output module  120  adjusts the regulated DC voltage to a level based on the power requirements of the portable electronic device  140  and outputs a voltage (V OUT ) to the portable electronic device  140 . 
         [0021]      FIG. 1B  is a block diagram of a modular power adapter according to an embodiment of the present invention. As shown in  FIG. 1B , modular power adapter  150  is configured in an AC mode and includes an AC input module  160 . The modular power adapter  150  also includes the DC output module  120 , which is also shown in  FIG. 1A . That is, the DC output module  120  is common to both the AC and DC modes. The AC input module  160  may be configured with interface connectors (not shown) so as to be detachable from the AC power source  170  and also from the DC output module  120 . The AC input module  160  receives AC power from AC power source  170  which may be configured as a wall outlet which may deliver 110V or 220V, for example. The AC input module  110  rectifies the AC voltage and generates a regulated DC voltage. The regulated DC voltage is provided to DC output module  120  which adjusts the regulated DC voltage to a level based on the power requirements of the electronic device  140  and outputs a voltage (V OUT ) to the portable electronic device  140 . Preferably, the DC output module  120  is detachably coupled to the electronic device  140 . 
         [0022]      FIG. 2A  is a perspective view of the modular power adapter  200 , configured in a DC mode. The adapter  200  includes the DC input module  110  and the DC output module  120 . The DC input module is configured with a cigarette lighter adapter  210  and an output jack (not shown) to receive an interface connector  220  on a cable  230  which is coupled to the input of the DC output module  120 . The DC output module  120  is further configured with a second interface connector  240  on cable  235 . The second interface connector  240  is configured to detachably couple to an input interface of a portable electronic device. 
         [0023]    On the other hand,  FIG. 2B  is a perspective view of the modular power adapter  250  configured in an AC mode. As shown in  FIG. 2B , the DC input module  110  with cigarette lighter adapter  210  (of  FIG. 2A ) has been replaced by the AC input module  160  with an AC input power cord  260 . Like the DC input module, the AC input module  160  is configured with an output jack (not shown) to receive interface connector  220  on cable  230  which is coupled to the input of the DC output module  120 . In a preferred embodiment, the AC input module may have dimensions of as 95 mm×71 mm×15.5 mm as shown in  FIG. 3 . 
         [0024]    As shown in  FIGS. 1A ,  1 B,  2 A, and  2 B, the modular power adapter may be configured in a DC mode or an AC mode by interchangeably coupling the DC output module  120 , which is common to both modes, to the either the DC input module  110  ( FIGS. 1A and 2A ) or the AC input module  160  ( FIGS. 1B and 2B ). This feature allows a user, for example, to use a laptop computer with a modular power adapter according to an embodiment of the present invention in the DC mode while traveling in a car by connecting the cigarette lighter adapter  210  to a cigarette lighter socket in the car and coupling the interface connector  240  to the laptop computer. If the user returns home or reaches a travel destination and wishes to continue working on the laptop computer in the AC mode, the user may simply disconnect the interface connector  220  from the DC input module  110  and leave the DC input module in the car connected to the cigarette lighter socket for later use. With the DC output module still connected to the portable electronic device, the user may connect AC input cord  260  to a wall outlet and couple interface connector  220  to AC input module  160 . 
         [0025]    On the other hand, if the user wants to switch back to DC mode, the user may disconnect the interface connector  220  from the AC input module  160 . The AC input module  160 , which is larger in size than the DC input module  110 , may be disconnected from the wall outlet and packed away in a travel bag, for example. The DC input module may be reconnected as described above. As such, by using the modular power adapter of the present invention, the user may easily switch from one power source to another with a single disconnect/connect cycle. 
         [0026]    As shown in  FIGS. 1-3 , the DC output module  120  is provided in a housing structure separate from the DC input module  110  and the AC input module  160 . Thus, the power conversion performed by the modular power adapter is spread across the selected input module and the DC output module. Accordingly, the modular power adapter according to the present invention distributes the heat produced by the modular power adapter. This increases the lifecycle of the modular power adapter as compared to conventional power adapters. This also makes the modular power adapter safer than conventional power adapters since it lessens the likelihood of heating the area around the adapter and lessens the likelihood of the user being burned when touching the modular power adapter. 
         [0027]      FIG. 4  is a block diagram of a DC input module  110  of a modular power adapter according to an embodiment of the present invention. Referring to  FIG. 4 , DC input module  110  may include an input circuit  410 , a control circuit  430 , a regulator circuit  440  and an oscillator circuit. The input circuit  410  may receive DC power from a DC power source which may be, for example, a cigarette lighter socket of an automobile or an airplane in-seat adapter capable of outputting about 12V of DC power. The input circuit  410  provides the DC voltage to the control circuit  430  and regulator circuit  440 . Oscillator circuit  450  generates a pair of triangle waves which are supplied to control circuit  430 . The output of the regulator circuit (V OUT ) is provided to control circuit  430  via a feedback path and used to set the duty cycle for the control circuit  430 . Based on the output voltage V OUT  in comparison to the triangle waves ( 455   a  and  455   b ) the control circuit  430  drives the regulator to increase or decrease the output voltage of the regulator to produce a regulated DC voltage V OUT  of about 32 V. The regulated DC voltage V OUT  may be output via output interface jack  460  along with a reference voltage V SW  of about 10V, and ground. 
         [0028]      FIG. 5  is a block diagram of the AC input module  160  of a modular power adapter according to an embodiment of the present invention. As shown in  FIG. 5 , AC input module  160  may include an input circuit  510 , conversion circuit  505 , a switching circuit  515 , a transformer  520 , a rectifier circuit  525 , and a control circuit  530 . The input circuit  510  may be configured to receive AC power from an AC power source such as a wall outlet which may output 110V or 220V of AC power, for example. The input circuit  510  provides the received AC power to the conversion circuit  505  which may be configured as a full wave rectifier or a half wave rectifier. The conversion circuit  505  converts the AC voltage to a DC voltage. The DC voltage is then supplied to the switching circuit  515 . The switching circuit  515  produces an AC voltage which is provided to the rectifier circuit  525  via transformer  520  under the control of control circuit  530 . The rectifier circuit  525  converts the AC voltage to a regulated DC voltage (shown as V OUT ) of approximately 32V. A different voltage level could be used according to design preference. The regulated DC output voltage V OUT  is then output to DC output module  120  via an output interface jack  560  and also fed back to control circuit  530  and used to produce a steady state voltage output. A reference voltage V SW  of approximately 10V and ground may also be provided via output interface jack  560 . 
         [0029]    The AC input module may also include output filters to reduce noise in the output and thus provide a more stable power output. Further, the AC input module may include a protection circuit to protect against overheating or undervoltage conditions, for example. 
         [0030]      FIG. 6  is a block diagram of the DC output module  120  of a modular power adapter according to an embodiment of the present invention. The DC output module  120  includes the interface connector  220 , input circuit  620 , a regulator circuit  630 , a control circuit  640  and the output interface connector  240 . Interface connector  220  is configured to mate with the output interface jack of the DC input module  110  or the AC input module  160 . Input circuit  640  receives power supplied by either the DC input module  110  or the AC input module  160  via interface connector  220 . Control circuit  640  monitors the output voltage which varies as the load of an electronic device  660  varies. The electronic device  660  is coupled to the output interface connector  240  of the DC output module  120 . Based on the sensed voltage, control circuit  640  controls the regulator circuit  630  to output an output voltage at a stable level required to operate the electronic device  660 . 
         [0031]    The DC output module  120  may further be configured with a protection circuit to prevent damage to components of the modular power adapter, the electronic device coupled thereto, and the consumer as a result of overheating. 
         [0032]      FIG. 7  is a schematic diagram of the a DC input module  110  of the modular power adapter according to an embodiment of the present invention. Referring to  FIG. 7 , the DC input module  110  includes input circuit  410 , regulator circuit  440 , control circuit  430 , and oscillator circuit  450 . Input circuit  410  receives a DC voltage such as 10V from a cigarette lighter, and provides various reference voltages (e.g., V SW  and V REF ) for operation of the DC input module  110 . The input circuit  410  may further include fuse (f 1 ) to provide overcurrent protection for the DC input module and thereby protect the modular power adapter and any electronic device coupled thereto. The input voltage V IN  is provided to the regulator circuit  440  and reference voltage V SW  is provided to the control circuit  430 . 
         [0033]    In an embodiment of the present invention, the regulator circuit  440  is configured as switched mode power supply with an operating frequency of approximately 100 KHz. Of course, one of ordinary skill would understand that other configurations for a regulator could similarly be used. For example, a linear power supply could be used. The regulator circuit  440  includes a pair of boost inductors  740   a  and  740   b,  to which the input voltage V IN  is applied. The boost inductors  740   a  and  740   b  are used to respectively generate outputs which differ in phase by 180 degrees under the control of the control circuit  430 . 
         [0034]    Oscillator circuit  450  includes a pair of transistors ( 750   a  and  750   b ) and is used to generate a pair of triangle waves Triangle- 1  and Triangle- 2 . Using these triangle waves, the oscillator circuit  450  sets the pulse width for the control circuit  430 . 
         [0035]    The control circuit  430  monitors the output voltage (shown as V SEN ) of regulator  440 . The voltage V SEN  is filtered and supplied to the inverting input of an operational amplifier  735  of a duty cycle setting circuit  730  of the control circuit  430 . The operational amplifier  735  compares the voltage V SEN  to a predetermined reference voltage V REF  (e.g., 2.5V) which is input to the noninverting input of the amplifier  735 . The output of amplifier  735  is used to set the duty cycle for the control circuit  430 . The triangle waves supplied by the oscillator circuit  450  are respectively input into the inverting inputs of comparators  732  and  734  on a first side  731   a  of the control circuit  430  (Triangle- 1 ) and the inverting inputs of comparators  736  and  738  on a second side  731   b  of the control circuit  430  (Triangle- 2 ). Voltage levels Control H and Control-L are set based on the output of amplifier  735  and respectively input to the non-inverting inputs of comparators  732 ,  736  and  734 ,  738 . The duty cycle setting circuit  730  is common to both the first side  731   a  and the second side  731   b  of the control circuit  430 . For ease of understanding, on the second side  731   b,  the Control H and Control-L signals generated by the duty cycle setting circuit  730  are shown as inputs to the comparators  736 ,  738 . 
         [0036]    The output of the comparator  734  (SW_DR_ 1 ) on the first side of control circuit  430  and the output of comparator  732  (SW_DR_ 2 ) on the second side of control circuit  430  are fed back to the oscillator circuit  450  and compared using comparator  752 . The output of comparator  752  is then used to adjust the pulse width of the triangle wave (Triangle- 2 ) provided to the control circuit  430  such that the current on both sides ( 731   a  and  731   b ) of control circuit  430  and thereby regulator  440  are balanced. This ensures that the output voltage V OUT  of the regulator  440  is stabilized at a particular voltage level. 
         [0037]    The input voltage V IN  (e.g., 10V) is applied to boost inductors  740   a  and  740   b.  When transistor  715   a  of the control circuit  430  is switch to an ON state, boost inductor  740   a  loads. When transistor  715   a  of the control circuit  430  is switched to an OFF state, the boost inductor  740   a  acts as a power source and the stored power is applied to transistor  745   a  until transistor  745   a  is forward biased thereby producing an increased output voltage as determined by the pulse width. Accordingly, DC input module can for example, take a 12-15 V input voltage and generate a steady state output such as 28V or 32V. 
         [0038]    Similarly, when transistor  715   b  of the control circuit  430  is switch to an ON state, boost inductor  740   b  loads. When transistor  715   b  of the control circuit  430  is switched to an OFF state, the boost inductor  740   b  acts as a power source and the stored power is applied to transistor  745   b  until transistor  745   b  is forward biased thereby producing an output which is 180 degrees out of phase with that produced via boost inductor  740   a.    
         [0039]    The output voltage V OUT  and reference voltage V SW  are output via output interface jack  460 . The DC input module  110  may also include an output filter  770  to reduce ripple voltage. 
         [0040]    The DC input module  110  may also be configured with protection circuits  780  and  790 . Protection circuit  780  includes a thermistor  785  to monitor the temperature and protects the DC input module from failures related to overtemperature conditions by preventing operation when the temperature reaches a predetermined level. On the other hand, protection circuit  790  protects the DC input module from failures related to undervoltage conditions operation by preventing operation when the input voltage V IN  is less that a predetermined reference voltage. 
         [0041]      FIG. 8  is a schematic diagram of the AC input module  160  of the modular power adapter according to an embodiment of the present invention. The AC input module  160  includes input circuit  510 , conversion circuit  505 , switching circuit  515 , transformer  520 , rectifier circuit  525 , and control circuit  530 . AC input circuit  510  receives AC power which may be for example 110V or 220V of AC power from a wall outlet. The input power may be filtered for noise reduction. The AC voltage is then supplied to the conversion circuit  505  which is configured as a diode bridge and converts the AC input voltage to an unregulated DC voltage. The unregulated DC voltage is provided to switching circuit  515  which generates an AC voltage based on a pulse width modulation (PWM) signal generated by control circuit  530 . When drive transistor  832  of switching circuit  515  is switched to an ON state based on a PWM signal, the AC voltage is provided to rectifier circuit  525  via transformer  520 . The rectifier circuit  525  converts the AC voltage to a regulated DC voltage V OUT  of approximately 32V. The output voltage V OUT  is filtered via output filter circuit  860  and output at output interface jack  560  along with a reference voltage (i.e., V SW ) of about 10V and ground. 
         [0042]    To generate the PWM signal which controls the drive transistor  832 , the AC input module  160  may further include an optocoupler ( 850   a  and  850   b ) and integrated circuit (IC)  855  such as the FAN6961 Quasi-resident Pulse Width Modulation Controller. Optocoupler  850   a,    850   b  maintains the isolation boundary between the primary and secondary sides of the transformer  520 . Further, optocoupler  850  provides a feedback path to monitor the output voltage and control the pulse width and thereby maintain a stable output voltage. 
         [0043]    The AC input module  160  may also be configured with protection circuit  880  which shuts down the AC input module  160  when the temperature reaches a predetermined level. 
         [0044]      FIG. 9  is a schematic diagram of the a DC output module  120  of the modular power adapter according to an embodiment of the present invention. The DC output module  120  may be detachably coupled to either the DC input module  110  or the AC input module  160  as described above without the need for further modification or additional adapters. In either case, the DC output module  120  receives an input voltage (V IN  of the DC output module=V OUT  of the input module  110  or  160 ) and a reference voltage V SW  from output interface of the input module coupled thereto. The DC output module  120  includes input interface connector  220 , input circuit  620 , regulator circuit  630 , control circuit  640 , and output interface connector  240 . The input interface connector  220  couples with the output interface jack of the selected input module (e.g.  460  of  FIG. 4 and 560  of  FIG. 5 ) to receive the input voltage V IN  and the reference voltage V SW  from the input module coupled thereto (i.e., the DC input module  110  or the AC input module  160 ). 
         [0045]    When transistor  905  of input circuit  620  is in an ON state, the input interface circuit  910  delivers input voltage V IN  to the regulator circuit  630 . As shown in  FIG. 9 , the regulator circuit may be configured as a synchronous buck converter. Other types of converters could also be used to regulate the power output to an electronic device. 
         [0046]    The regulator circuit  630  which may operate at an operating frequency of 130 KHz, for example, adjusts the output to an electronic device using a PWM signal generated by the control circuit  640 . The control circuit  640  monitors the output voltage coupled to the output interface connector  240  and generates signals which are used for voltage regulation and for current regulation. In block  930 , comparator  935   a  is used for voltage regulation and monitors the output voltage V OUT  and compares V OUT  to a reference voltage. This reference voltage may be programmed for example, by components such as resistors which are external to the DC output module  120 . Such resistors may be located in a connector adapter (“tip”) which interfaces with the electronic device. The output of comparator  935   a  is used to control IC  945  such as a MIC4100 half bridge driver and the ON/OFF times of transistors  922  and  924 . Thus, the regulator circuit  630  is controlled to produces an output voltage V OUT  at a level such that the electronic device may be safely operated. 
         [0047]    A 5V reference voltage may also be supplied to the DC output module  120  via output interface connector  240  as a source for the program voltage V PROG  which is input via the output interface connector  240 . 
         [0048]    Similarly, the output current is sensed and provided to comparator  935   b  which compares the output current to a reference to assist in power regulation. I PROG  is input via output interface connector  240  and sets a limit as to how much output current may be supplied by the DC output module  120  safely (i.e., before the DC output module  120  is shutdown due to excessive current). 
         [0049]      FIG. 10  is a flow diagram illustrating a method for providing a modular power connection according to an embodiment of the present invention. In step  5 , a voltage is received from a power source via an input power module. The input power module may be configured to receive an AC voltage or a DC voltage. The input power module converts the input voltage to DC if an AC voltage is received. In either case, in step  10 , the input power module regulates the unregulated DC voltage and outputs the regulated DC voltage. The regulated DC voltage may further be filtered to provide a more stable output voltage. In step  15 , the regulated DC voltage is then supplied to an output power module. In step  20 , the output power module adjusts the regulated DC voltage to produce an output voltage and outputs the output voltage via an output interface. 
         [0050]      FIG. 11  is a flow diagram illustrating a method for providing a modular power connection according to an embodiment of the present invention. Referring to  FIG. 11 , in step  25 , the user connects a portable electronic device to the DC output module. In step  30 , the user selects a power source and a corresponding input module (DC input module  110  or AC input module  160 ) to enable operation of the portable electronic device. In step  35 , based on the power source selected, the user connects the DC output module to the selected input module by inserting the input interface connector of the DC output module into the output jack of the input module. When an AC source is selected the user connects the AC input module  160  to the DC output module  120 . On the other hand when a DC source is selected, the user connects the DC input module  110  to the DC output module  120 . In step  40 , the user connects the input module to the selected power source. When the AC input module  160  is selected, the user connects power cord  260  to an AC source such as a wall outlet, and when the DC input module  110  is selected, the user connects cigarette lighter adapter to a DC source such as a cigarette lighter socket in a car. In step  45 , the user operates the electronic device. In step  50 , the user turns off the portable electronic device. In step  55 , the user disconnects the DC output module from the input module. When the user is ready to operate the electronic device, the user may repeat steps  30 - 45  to couple the electronic device to a power source. 
         [0051]    Since the AC input module  160  and the DC input module  110  are easily interchangeable a user may quickly switch from an AC power source to a DC power source and vice versa by simply disconnecting the input interface connector  220  of the DC output module  120  from the currently employed input module ( 110  or  160 ). The user may then connect the input interface connector  220  of the DC output module  120  to the output jack of the input module for the power source that the user wishes to use. For example, if the user has connected an electronic device to a DC power source, such as a cigarette lighter socket, in a car using the modular power adapter including the DC input module  110 , and decides to switch to an AC source, the user disconnects the input interface connector  220  of the DC output module  120  from the output jack of the DC input module  460 , leaving the DC input module  110  in the car for later use. Then, with the DC output module  120  still connected to the portable electronic device, the user could then move to a location having an AC source. The user may then insert the input interface connector  220  of the DC output module into the output jack  560  of the AC input module  160 . An AC power cord  260  is coupled to the AC input module and plugged into an outlet for the AC source thereby enabling operation of the portable electronic device. 
         [0052]    While the description above may refer to particular embodiments of the present invention, it will be understood that many alternatives, modifications and variations may be made without departing from the spirit thereof. The accompanying claims are intended to embrace such alternatives, modifications and variations as would fall within the true scope and spirit of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention by the claims, rather than the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.