Abstract:
A power-sharing controller module comprises a processor, power manager, and at least one connector for detachably electrically connecting an application module to the controller module. The power manager is operable to manage power from a battery to the application module through said connector and to monitor the voltage of the battery. The processor is programmed to send a power reduction command to the application module in response to the monitored battery voltage moving outside of a permissible range.  
     A power sharing method comprises supplying power from the battery in the controller module to the application module detachably connected to the controller module. Power supplied to the application module is reduced in response to an adverse power indication to conserve power for the controller module.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    This invention relates to electronic systems, and more particularly to power sharing methods and systems.  
           [0003]    2. Description of the Related Art  
           [0004]    Electronic devices which capture, create, store, manipulate and/or transfer digital music, sound, images, movies or other encoded data have become more prevalent with the advent of less-expensive semiconductor processing and increased consumer demand. Applications such as portable MP3 (Moving Picture Experts Group layer 3 standard) players, PDAs (electronic personal data assistants), digital cameras and digital voice recorders continue to gain popularity. The general trend for each of these electronic applications is toward miniaturization and improved battery management.  
           [0005]    These are several products with advanced battery management. One such product provides for an early warning to critical systems when the power-supply voltage for the system begins to fail. The warning enables the system microprocessor to perform essential tasks before a hard reset must be issued to turn off the system due to low supply voltage. The company also advises that system shutdown may be accomplished using a single threshold voltage detector in combination with a delay timer for the reset signal to ensure that the system voltage supply remains valid long enough to complete the system shutdown routine. (See Maxim Integrated Products, Inc.,  Low Battery Monitor Delays System Shutdown , P.1 (Jul. 9, 1998))  
           [0006]    Another solution can be found in the MC33351A power management IC (integrated circuit) offered by ON Semiconductor Corporation (with headquarters in Phoenix, Ariz.). This IC features a programmable current level for individual battery cells and two P-channel MOSFET (metal oxide silicon field effect transistor) switches to interrupt the appropriate discharge path FET (field effect transistor) in the event a parameter is exceeded. (See  On Semiconductor Unveils Power Management IC , Electronic Component News, ¶4-5 (Nov. 15, 2000)) The IC also provides for a shutdown delay once a threshold is exceeded for a discharge current limit (Id. at ¶5). Similar to the previously described solution, the IC is designed for laptop and other single microprocessor applications.  
         SUMMARY OF THE INVENTION  
         [0007]    A system and method are described that protect a controller module from excessive battery discharge by an application module. In this context, a need still exists for a power management system and method for a multiprocessor system. In one embodiment of the invention, power is supplied from a battery in the controller module to a detachably connected application module, and the power supplied to the application module is reduced in response to an adverse power indication to conserve power for the controller module.  
           [0008]    An embodiment of a power sharing controller module includes a processor, power manager and at least one connector for detachably electrically connecting an application module to the controller module. The power manager is operable to provide power from a battery to the attached application module through the connector and to monitor the voltage of the battery. The processor is programmed to send a power reduction command to the application module in response to the monitored battery voltage moving outside of a permissible range. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]    The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principals of the invention. Moreover, in the figures, like reference numerals designate-corresponding parts throughout the different views.  
         [0010]    [0010]FIG. 1 is an exploded perspective view illustrating an embodiment of a portable modular electronic device in which embodiments of the invention may be used to advantage.  
         [0011]    [0011]FIG. 2 is a block diagram of one embodiment of the invention illustrating a controller module having a processor and power manager, the processor in communication with an application module and memories A and B.  
         [0012]    [0012]FIG. 3 is a flow diagram of an embodiment of the invention able to send an immediate shutdown command to an application module in response to an adverse power indication.  
         [0013]    [0013]FIG. 4 is a flow diagram of another embodiment able to send a shutdown command to an application module after a time delay in response to an adverse power indication.  
         [0014]    [0014]FIG. 5 is a flow diagram of an embodiment in which the application and controller modules are shut down in response to an excessive battery voltage. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0015]    A portable modular system with detachably connectable controller, memory and application modules, has been proposed by the present inventors. This system is the subject of application Ser. No. 10/307,034, filed Nov. 27, 2002, “Portable Modular Electronic System”. An improved battery management scheme for such a system is particularly important, since the battery may be drained at a location where a replacement battery is not available.  
         [0016]    In FIG. 1, a controller module  100  is aligned for electrical connection to an application module  105  through an electrical connector  110  in the application module  105  and a complementary, opposed connector (not shown) in the controller module  100 , and for mechanical connection to the application module by connectors  115 . The controller module manages power sharing between itself, application module  105  and a pair of memories A, B that are also modular. Memories A, B are both electrically and mechanically connectable to the controller module.  
         [0017]    The application module  105  may be any portable electronic consumer application such as a video/still image player or reviewer, a PDA, a digital still or video camera, or an MP3 player. It can also be connected in turn to additional application modules  116  through electrical and mechanical connectors  110 ,  115  similar to those used to connect the controller module to the memories and first application module. With the second application module connected, the controller module  100  provides power to it through an opposing electrical connector (not visible) on the first application module  105 . Application user interfaces  117 ,  118  are also provided on application modules  105  and  116 , respectively, to provide application-specific information to a user.  
         [0018]    The illustrated electrical connector  110  has four concentric electrical contacts, providing two data paths and two power paths between the modules ( 100 ,  105 ). Many different electrical and mechanical connection schemes can instead be employed. In the embodiment of FIG. 1, the connectors for adjacent modules are unisex in nature and spring-biased to extent slightly outward from their respective modules, providing a secure electrical contact when brought in to contact with each other and held in place with the mechanical connectors  115 . A user interface  120  on the controller module provides information to, and accepts alphanumeric text or other input from, a user. An AC (alternating current) input port  125  is also provided to facilitate power input for battery charging and battery-less operation.  
         [0019]    Memories A and B are shown aligned for electrical connection to the controller module  100  through respective electrical connectors  110  in the controller module, and a complementary pair of electrical connectors (not shown) in the memories, one for each memory. Each memory can be individually replaced if it goes bad, and a new memory installed.  
         [0020]    [0020]FIG. 2 illustrates an implementation of a controller module  100  that enables it to manage power sharing between itself, the application module  105  and the memories A and B. In the figure, power connections are indicated by dots and data inputs by arrows. The controller module includes a data bus  200  in communication with a controller  205 , a user interface  120 , an internal memory  215 , and a processor  220 . The processor  220  and controller  205  may be integrated into a single chip. Similarly, the internal memory  215  may be integrated onto a single chip with either the processor  220  or controller  205 , or both.  
         [0021]    The processor  220  is programmed to provide several functions, including a trouble monitor  225  and a read/write circuit  230 . The trouble monitor  225  detects whether memories connected to the processor  220  are operating correctly, and notifies the user of adverse power indications or other user problems through the user interface  120 . The read/write circuit  230  communicates with the application module  105 , and governs the read/write of data to and from memories A and B. Elements  225  and  230  may be implemented in firmware, or with a software controlled general purpose DSP (digital signal processor). The data bus  200  is illustrated with electrically conductive paths between the processor  220 , controller  205 , user interface  120 , and internal memory  215 . Other signal transport mechanisms, such as an optical bus, may also be used.  
         [0022]    The modular system described thus far is only one in which embodiments of the invention may be used to advantage. Many variations can be made to the implementations of the modules within the scope of the invention.  
         [0023]    The controller module  100  also includes a battery compartment  237  which is supplied with a battery  235 , either by the user or by the original manufacturer or dealer. The compartment can be any suitable structure that keeps the battery connected to a pair of battery terminals, and does not have to be a housing or enclosure. The battery supplies power to a power manager  240  through a voltage regulator  250  that steps down the battery voltage to a regulated level for the system. An output  245  from the battery compartment  237  enables the power manager  240  to directly monitor the battery&#39;s voltage V B . Alternatively, the output of regulator  250  can be monitored for an indication of the battery voltage V B .  
         [0024]    The power manager includes a battery voltage monitor circuit  252  that is preferably connected to both the battery output  245  and voltage regulator  250  for monitoring their voltages, although it can alternately be connected to only one or the other. It also includes memory, controller module, and application module safety circuits  255 ,  260  and  265 , respectively, in series with the voltage regulator  250  to terminate the supply of power to memories A and B, the remainder of the controller module  100 , and the application module  105 , respectively, in response to excessive current, power, or voltage drawn by these components. A delay timer circuit  270  may also be included in the power manager  240  to provide an optional time delay prior to terminating power supply in response to a low battery voltage indication from the battery voltage monitor circuit  252 .  
         [0025]    The power manager  240  transmits power at the regulated voltage level from the voltage regulator  250  to memories A and B, the application module  105  and the controller module  100 . A switch  272  is in series with the power manager  240  and application module  105  to provide power to the application module  105  when engaged by the user. A power bus  270  distributes power from the power manager  240  to the processor  22   b , controller  205 , user interface  120 , and internal memory  215 . The controller module safety circuit  260  is also connected between the regulator  250  and the power bus  270  to protect the controller module  100  from excessive current. The safety circuits ( 255 ,  260 ,  265 ) reduce or terminate the supply of power to their respective protected circuits, and are preferably implemented as fuses or breakers that trigger at predetermined fault current levels. The application module safety circuit  265  also includes a switch (not shown) that opens or closes in response to a signal from the processor  220 .  
         [0026]    Instead of providing a common supply voltage, the power manager  240  can be configured to provide different respective voltage levels to the application module  105 , processor  220 , memories A and B, and the remainder of the controller module  100 . The power bus  270  would then be split into separate power busses for the processor  220 , controller  205 , user interface  120 , and internal memory  215  components as appropriate.  
         [0027]    The battery  235  has a rated voltage that is normally greater than the output voltage of the voltage regulator  250 . The processor  220  communicates with the application module  105  through the data bus  200  to shut down the application module  105  when an adverse power indication is received by the processor indicating a battery voltage V B  that is less than a predetermined voltage level below the rated battery voltage. Preferably, the processor  220  transmits a shutoff command to the application module  105 . Or, it can simply cut off power to the application module  105  by operating a switch  273  in the application module safety circuit  260 .  
         [0028]    The internal memory  215  buffers files received from the application module  105  to enable efficient reads and writes by the read/write circuit  230  from and to memories A and B, through data paths  285  and  290 , respectively. An AC-DC Converter  275  is connected between the AC input port  125  and the power manager  240  to enable direct connection to a conventional AC voltage source.  
         [0029]    In an embodiment illustrated by the flow diagram of FIG. 3, a warning is provided to a user in response to the battery (or regulated) voltage falling below a first threshold level. The warning is provided when the monitored voltage falls below a second threshold level prior to shutdown of the application modules. The battery voltage V B  is monitored either at the battery output  245 , or from the output of the voltage regulator  250 , for an adverse power indication in the form of a predefined low battery voltage level (block  300 ). When the battery voltage V B  is less than the warning voltage V B(Low)  (block  305 ), a warning is sent to the user interface  120  to notify a user of the low voltage condition (block  310 ). This gives a user an opportunity to conclude use of the application module  105  prior to its shutdown. A warning may also be sent to the application module  105  to enable it to optionally begin pre-shutdown housekeeping activities, and to optionally display a warning in its application user interface  117 . If the battery voltage V B  continues to fall and drops below a second predetermined voltage level V B(SHDN)  (i.e., less than the rated battery voltage and the warning level (block  315 ), but still sufficient to operate the controller module), a shut-down command is sent to the application module  105  (block  320 ). The battery voltage monitor circuit  215  continues to monitor the battery voltage V B  at the battery output  245  or at the output of the voltage regulator  250  (block at  325 ). With power reduced or totally shut off to the application module  105 , the drain on the battery is greatly reduced, and the period of time the controller module can continue to operate before the battery is refreshed is correspondingly entered. If the battery voltage V B  eventually falls below a reset voltage V B(RESET)  at the minimum level required for controller module operation (block  330 ), existing files buffered in the internal memory  215  of the controller module  100  are saved to memories A and B (block  335 ), and the controller module  100  and memories A and B are shutdown (block  340 ) until proper battery voltage is restored.  
         [0030]    Instead of a total shutdown, the application and controller modules ( 100 ,  105 ) can be programmed to respond to their respective shutdown commands by entering a either a sleep mode to reduce functionality such as computing tasks, internal mechanical functions or displays in combination with continued monitoring of the battery voltage V B  and the data bus  200 , or a stepped reduction of power such as, for example, a 40% reduction then a 60% reduction. Also, if more than one application module  105  is in communication with the controller module  100 , each either responds in a predetermined-shutdown sequence or as each application module receives its shutdown command.  
         [0031]    Once the adverse power indication from the battery output  245  is removed, the controller module  100  and/or application module  105  would then return to normal operation without further prompting by the user.  
         [0032]    [0032]FIG. 4 is a flow diagram of an embodiment in which a warning is provided to the user a predetermined period of time before the application module is shut down. As in FIG. 3, the battery&#39;s voltage V B  is monitored (block  400 ) and, if it is less than a predetermined warning voltage V B(LOW) , an adverse power indication is registered by the processor  220  (block  405 ) and a warning is sent to the application module  105  from the controller module  100 , (block  410 ). The delay timer circuit  270  is activated (block  415 ) and, after its delay period has elapsed (block  420 ), a shutdown command is sent to the application module  105  to conserve power for the controller module (block  425 ). A warning could also be sent to the application module and/or user interface when the delay timer circuit is activated. In this embodiment, the application module is shut down a predetermined delay period after the warning has been given, regardless of the battery voltage level at the time of shutdown. Alternately, the system could be programmed to shut down the application modules if the delay period has expired and the battery voltage has also dropped below a shutdown threshold.  
         [0033]    [0033]FIG. 5 illustrates an embodiment of the invention that protects the controller module  100  from receiving excessive battery voltage V B . The battery voltage V B  is monitored (block  500 ) and, if it exceeds a predetermined level (block  505 ), an adverse power indication is registered in the processor  220 . For example, failure of either the AC-DC converter  275  or regulator  250  to convert or step down their respective input voltages may result in the supply voltage to the power manager  240  rising above the predetermined voltage level. In response, a shut-down command is sent to the application module  105  (block  510 ) and, optionally, a warning to the user. The, files buffered in internal memory  215  are saved to memories A and B (block  515 ), and the controller module is also shutdown (block  520 ). As described above for FIG. 3, the shutdown command (block  520 ) may initiate a sleep-mode, rather than a complete power down of the application and controller modules ( 100 ,  105 ). The reduction of power to the application module occurs whenever the battery voltage moves outside of a permissible range. If the system monitors only for a low battery voltage, the upper end of the range is unlimited. If it monitors for both high and low battery voltages, the upper and lower ends of the range will both have finite limits.