LP2952 Datasheet, PDF (17/22 Pages) National Semiconductor (TI) – Adjustable Micropower Low-Dropout Voltage Regulators

Typical Applications (Continued)
5V Regulator with Error Flags for
LOW BATTERY and OUT OF REGULATION
* Connect to Logic or µP control inputs.
01112718
LOW BATT flag warns the user that the battery has discharged down to about 5.8V, giving the user time to recharge the battery or power down some hardware
with high power requirements. The output is still in regulation at this time.
OUT OF REGULATION flag indicates when the battery is almost completely discharged, and can be used to initiate a power-down sequence.
5V Battery Powered Supply with Backup and Low Battery Flag
01112719
The circuit switches to the NI-CAD backup battery when the main battery voltage drops below about 5.6V, and returns to the main battery when its voltage is
recharged to about 6V.
The 5V MAIN output powers circuitry which requires no backup, and the 5V MEMORY output powers critical circuitry which can not be allowed to lose power.
* The BATTERY LOW flag goes low whenever the circuit switches to the NI-CAD backup battery.
17
www.national.com