LP2952-N, LP2952A, LP2953, LP2953A

SNVS095F – MAY 2004 – REVISED MARCH 2015

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8.2.5 5-V Battery Powered Supply With Backup and Low Battery Flag

Figure 39 is the example circuit for 5-V battery powered supply with backup and low battery flag, it has the

following features:

•

The circuit switches to the NI-CAD backup battery when the main battery voltage drops below about 5.6 V

and returns to the main battery when its voltage is recharged to about 6 V.

•

The 5-V MAIN output powers circuitry which requires no backup, and the 5-V MEMORY output powers critical

circuitry which cannot be allowed to lose power.

•

The BATTERY LOW flag goes low whenever the circuit switches to the NI-CAD backup battery.

Figure 39. 5-V Battery Powered Supply With Backup and Low Battery Flag

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