Patent Publication Number: US-2009240863-A1

Title: Distributed power regulation

Description:
FIELD OF INVENTION 
     The present invention relates to handheld electronic devices, and more specifically to a method and system for distributed power regulation for a handheld electronic device. 
     BACKGROUND OF THE INVENTION 
     Power management for handheld electronic devices is one of the important design factors. Referring to  FIG. 1 , there is illustrated a power distribution architecture in a conventional handheld electronic device  10 . The handheld electronic device  10  includes a battery  12 , a plurality of power supply units (PSUs)  14   a - 14   c,  an interface controller  16 , and an expansion interface  18 . The expansion interface  18  has pins that are capable of connecting the handheld electronic device to a peripheral device. In the handheld electronic device  10 , a single battery power rail is connected to multiple PSUs  14   a - 14   b.  Each of the PSUs  14   a - 14   c  converts its input voltage into a fixed voltage (e.g., 1.8V, 3.3V). The voltage from each PSU is supplied to the expansion interface  18  so that the peripheral device plugged into the expansion interface  18  will receive a power from the expansion interface  18 . 
     In the handheld electronic device  10 , the source voltage from the battery  12  should be converted into multiple voltages, according to the corresponding voltage requirement. Thus, the amount of current drawn to each pin of the expansion interface  18  is limited. The designer often does not know the voltage or current demands of future peripherals. Thus, it is required to generate larger power more than what is required and use larger connectors and larger pins, in order to meet possible current requirements. This requires more real-estate and cost. In addition, as an available space is limited in the handheld electronic device  10 , the type of peripherals plugged into the expansion interface  18  would be limited. The conventional power splitting method lacks flexibility of future expansion, and cannot be manipulated by the peripheral designer. 
     Therefore, there is a need to control power distribution to peripherals of a handheld electronic device while allowing for maximum flexibility and expandability. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an improved method and system that obviates or mitigates at least one of the disadvantages of existing systems. 
     According to an aspect of the present invention there is provided a system for power regulation in a handheld electronic device having a battery. The system includes an expansion interface for receiving a battery power from the battery; and a peripheral interface system releasably coupled to the expansion interface and communicating with a peripheral device for generating one or more predetermined operation powers for the peripheral device, based on the battery power provided through the expansion interface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
       These and other features of the invention will become more apparent from the following description in which reference is made to the appended drawings wherein: 
         FIG. 1  is a block diagram illustrating an expansion system in a conventional handheld electronic device for power distribution system to a peripheral device; 
         FIG. 2  is a block diagram illustrating an example of an expansion system in a handheld electronic device for power distribution to a peripheral device, in accordance with an embodiment of the present invention; 
         FIG. 3  is a block diagram illustrating the expansion system of  FIG. 2  and an example of a peripheral expansion unit having a power supply system; 
         FIGS. 4-5  are diagrams illustrating an example of a peripheral interface connector and associated components of  FIG. 3 ; 
         FIG. 6  is a side view of an example of a printed circuit board layout associated with components of  FIGS. 4-5 ; and 
         FIG. 7  is another side view of the printed circuit board layout. 
     
    
    
     DETAILED DESCRIPTION  
     Embodiments of the present invention provide a power distribution system for a handheld electronic device, where a power is distributed without splitting a source power from a battery. The handheld electronic device may be, but not limited to, a cellular telephone, a PDA, a combination digital device, a portable rugged or semi-rugged data collection terminal, a handheld two-way radio, a wireless bodyworn communication device. In the description, the terms “handheld” and “portable” may be used interchangeably. The system provides a power or current demanded by a peripheral without using multi power supply units. 
     Referring to  FIG. 2 , there is illustrated an example of an expansion system in a handheld electronic device for power distribution to a peripheral device, in accordance with an embodiment of the present invention. The expansion system  30  of  FIG. 2  is mounted in a handheld electronic device. 
     It is well understood by one of ordinary skill in the art that the handheld electronic device having the expansion system  30  may contain components/elements/electronics not illustrated in  FIG. 2 . For example, the handheld electronic device includes a main logic board (or a printed circuit board (PCB)) having a processor and a memory. 
     The system  30  includes a battery  32 , an interface controller  36 , and an expansion interface  38 . The battery  32  is used to provide operation power to the electronics of the handheld electronic device, and also provide power to peripheral circuitry when it is coupled to the expansion interface  38 . The battery power is supplied to the expansion interface  38  through the main logic board. 
     The expansion interface  38  may be a group of wires, a connector or contacts on the PCB. The expansion interface  38  couples a peripheral expansion unit (e.g.,  40  of  FIG. 3 ) to the main electronics of the handheld electronic device. 
     The interface controller  36  is a group of digital and/or analog signals used to control and/or communicate with the peripheral or electronic circuits in the handheld electronic devices. The interface controller  36  may include a single controller, multiple controllers, a sub section from a controller or any combinations thereof. 
     The interface controller  36  may be on a main logic board of the handheld electronic device. Both of the interface controller  36  and the expansion interface  38  may be on the main logic board. 
     A single power from the battery  32  is directly supplied to the peripheral expansion interface  38  without modifying or splitting the battery power. This single power allows the system  30  to provide greater current options to a peripheral expansion unit (e.g.,  40  of  FIG. 3 ) where the peripheral expansion unit produces voltage required in the peripheral circuitry (e.g.,  46  of  FIG. 3 ). Power supply regulation for the peripheral circuitry is employed in the peripheral expansion unit after the connection of the peripheral expansion unit and the expansion interface  38 . 
     The system  30  allows for flexibility of power usage at the peripheral expansion unit, resulting in reducing cost/size of principle terminal while cost/size may be moved to the peripheral expansion unit. 
     The power distribution may be managed by hardware and/or software based control, which allows for peripheral to sleep or draw power as demanded. This control is designed to maximize battery life. 
       FIG. 3  is a diagram illustrating the expansion system of  FIG. 2  and an example of a peripheral expansion unit having a power supply system. It is well understood by one of ordinary skill in the art that the configuration of  FIG. 3  is an example only, and the configuration of the system may vary. 
     The peripheral expansion unit  40  of  FIG. 3  includes an peripheral interface  42 , a power supply system  44 , and peripheral circuitry  46 . The peripheral expansion unit  40  is releasably coupled to the expansion interface  38  through the peripheral interface  42 . The peripheral interface  42  receives a single power from the expansion interface  38  when it is coupled to the expansion interface  38 . The peripheral interface  42  has one or a group of pins for supplying the single power with the maximum current to the power supply system  44 . 
     The peripheral interface  42  and the power supply system  44  may be on a printed circuit board (PCB) (e.g.,  FIGS. 6-7 ). The peripheral interface  42 , the power supply system  44  and the peripheral circuitry  46  may be on the PCB. 
     The power supply system  44  includes a plurality of PSUs (e.g.,  44 A,  44 B,  44 C), each of which receives a single voltage from the peripheral interface  42 , through a power line  50 , and converts the voltage into a fixed voltage. In  FIG. 3 , PSUs  44 A- 44 C are illustrated separately, however, they may be integrated into one circuit. 
     The peripheral interface  42  manages the operation of the PSUs  44 A- 44 C by providing an enable signal  52 . The enable signal  52  is provided to each of PSUs  44 A- 44 C, by which the corresponding PSU will operate. The PSUs  44 A- 44 C turn on altogether or in sequence, based on the enable signal  52  from the peripheral interface  42 . For example, it is assumed that the PSU  44 A is capable of producing 5.5 volts while the PSU  44 B is capable of producing 3.3 volts. When the peripheral circuitry  46  requires 3.3 volts, the system  40  may enable the PSU  44 B and disenable the PSU  44 A. In another example, the PSU  44 A- 44 C are enabled to draw the maximum current across all of the power pins of the peripheral interface  42 . The peripheral expansion unit  40  can allocate current/voltage to the peripheral circuitry  46  as demanded. 
     The peripheral interface  54  is coupled with the peripheral circuitry  46  through a communication bus  54 . The peripheral interface  42  supports standard protocols, such as Universal Serial Bus (USB), Serial Bus, and Compact Flash (CF). The peripheral interface  42  interfaces with the peripheral circuitry  46  to receive/transmit relevant information/data according to, for example, USB, Serial Bus, and CF formats. 
     The PSUs  44 A- 44 C are in the peripheral expansion unit  40  and is on the PCB. The designer can designs the PSUs  44 A- 44 C with the peripheral circuitry  46  or use suitable PSUs  44 A- 44 C, based on voltage or current demands from the peripheral device. It is not required to modify the expansion system  30  (e.g., interface controller  36 , expansion interface  38 ) to meet the requirements of voltage and current for the peripheral circuitry  46 . Thus, this allows for future expansion of the handheld electronic device&#39;s capability, without redesign of the expansion system  30 . 
     The controls through the peripheral interface  42  may include a high level control and a low level control where the high level control includes the power distribution, and the low level. control does not depend on the high level control and state independent and control peripheral (sleep/awake). 
     Referring to  FIGS. 4-5 , an example of a peripheral interface connector and associated components is described. There are three components in  FIGS. 4-5 , connector (J 1 )  102 , module (J 2 )  104 , and a switcher (U 1 )  106 . These components are the peripheral interface connector and the associated components to connect the control line ( 54  of  FIG. 3 ) to the peripheral circuitry ( 46  of  FIG. 3 ). These also allow various USB compatible devices to be connected internally to the expansion interface. 
     The power and USB signals are connected to a handheld electronic device via the connector  102 . The communications signals “USB_DN” and “USB_DP” are standard USB host connection signals from the main logic board of the handheld electronic device. Power is switched on the MLB and supplied via the connector  102  on main power net “VDD_MAIN_BAT”. 
     The main power net “VDD_MAIN_BAT” is connected via a slew rate controlled switch to the battery of the handheld electronic device. The battery voltage can vary from, for example, 3.2V to 4.2V and supply up to, for example, 1.5 Amps maximum. The battery voltage is then boosted via a step-up switching power supply to, for example, 5V. The step-up switcher  106  boosts the supply by charging  120  (L 2 ) and catching the released energy via  122  (D 1 ). The capacitor  124  (C 1 ) smoothes the input voltage and component  126  (C 2 ) smoothes the output supply on net “VDD — 5V0”. Two resistors  130  and  132  (R 1  and R 2 ) control the output voltage. Capacitor  134  and resistor  136  (C 5  and R 3 ) control the dynamic response of the switcher  106 . 
     The generated supply (“VDD — 5V0”) and the USB signals (“USB_DN” and “USB_DP”) are supplied to the module  104  to allow peripheral connection. The peripheral connection may include a connection to expansion electronics mounted in a separate section, which may contain a thumb print reader. Capacitors  110  and  112  (C 3  and C 4 ) and inductor  114  (L 1 ) add further filtering of high frequencies to prevent the circuit from radiating noise in to the adjacent radios. 
       FIGS. 6-7  illustrate an example of a printed circuit board layout for an onboard power regulation applicable to  FIG. 3 . Components are laid out on the components side and the solder side of the board, (e.g., J 1 , J 2  and U 1  of  FIGS. 4-5 ). 
     One or more currently preferred embodiments have been described by way of example. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.