Electronic devices continue to get smaller and incorporate more functions. It is well known to incorporate the functions of a traditional personal digital assistant (“PDA”) with wireless email capability into a single device, the Blackberry™ from Research in Motion of Waterloo, Canada being an example of such a device. It is also known to incorporate wireless voice functionality, music and video players into such devices. Increasingly, cameras are being incorporated into such devices.
With integration, so too comes increased device complexity. Power management in the device needs to reflect that complexity. For example, due to the portable nature of these devices, a robust rechargeable battery is desirable, if not a necessity, to satisfy user demands. However, even with a robust rechargeable battery, sophisticated power management techniques are needed to optimize battery use.
However, power management in such devices still needs much improvement. One particular vexing problem is the camera flash. When the battery is low, or cold, the battery ESR may be too high to support a camera flash. The camera flash is a high drain on the battery for a long period of time. It is not uncommon for a camera flash to draw up to about one ampere (Amp) of power from the battery for up to about eighty milliseconds (ms). This draw can cause battery “droop”. In such cases the battery droop may be such to trip battery supervisory circuits, causing the handset to reset or go into sleep mode. This can be a frustrating experience for the user.
One approach to try and address this problem is to map known levels of battery capacity and voltage into tables that are associated with events that should occur at those battery capacity levels. This can be an effective approach for components that draw relatively small or steady amounts of power. However, for a flash or other high-intensity component, a large margin of battery reserve is needed as the momentary conditions of a battery that can withstand such a high-intensity burst can vary. Accordingly this approach is not a satisfactory option for at least some situations.