AN-1028 Datasheet, PDF (1/3 Pages) Fairchild Semiconductor – Maximum Power Enhancement Techniques for SOT-223 Power MOSFETs

AN-1028
Application Note
Ultra Low Power MSP430 Backup Using the EnerChip™ CC
Introduction
Cymbet EnerChips are solid state rechargeable batteries having distinguishing characteristics compared to
conventional rechargeable batteries. EnerChips have a high charge/discharge cycle life; low self-discharge;
simple voltage controlled charging; flat discharge voltage profile; have no flammable solvents to leak or catch
fire; are solder reflow tolerant; and are offered in low profile surface mount packages.
The EnerChip CC is a surface mount package containing a rechargeable solid state battery - the EnerChip -
with integrated battery management that includes charge control, discharge cutoff circuitry, and a battery
switchover (i.e., supply supervisory) function. EnerChips are used in applications requiring backup, bridging,
or transition power to maintain real-time clock operation or SRAM data retention in the event of main power
interruption; wireless sensing as the main power source when energy can be harvested from the ambient
power and used to constantly trickle charge the EnerChip; and as a power source to perform housekeeping for
microcontrollers (MCUs) and peripherals when main power is interrupted, to ensure an orderly shutdown or
transition to low power modes.
In applications demanding ultra low power consumption, where the system uses a Texas Instruments MSP430
microcontroller, it is essential to reduce or eliminate the power drawn by components peripheral to the
MSP430. This Application Note describes a method to completely eliminate the power drawn by the EnerChip
CC integrated battery management circuitry when the system is in the normal operating mode. This approach
enables a backup battery solution that does not draw power when in normal run mode, thus maximizing the
main battery life in battery powered systems.
Figure 1. Ultra Low Power Application Circuit Using the EnerChip CC and MSP430 Microcontroller.
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Doc AN-72-1028 Rev B
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