We are working with ARM7, for RTC we are using the in built RTC in the Processor.Simple multiplexer circuit (TS5A3159) Mux is used
Connections:
Normally Closed Pin:Connected to CMOS (RTC)Battery 3.3V
Normally Opened Pin: Connected to external 3.3V Power supply
Select Pin: Connected to Powerstart Pin of Processor

Expected Behaviour:
As per expectation when select Pin is low,power should come from normally closed pin to the Mux output pin,when Select Pin is high power should come from normally opened pin to the Mux output pin.

Current behaviour of MUX:
when Select Pin is Low,power is taken from Normally closed to Mux output pin and also power is going to the input normally opened pin(here external 3.3V is not given to normally opened Pin).Due to this our CMOS(RTC) Battery gets discharged rapidly as this normally Opened pin feeds other parts of the circuit -[power is taken from CMOS to Other parts of Circuit]

Can you please provide solution for this ? Give sample circuit that uses inbuilt RTC.

Thanks in advance,
qualitycore

 

Can you post a schematic of your current set-up?