Low Battery protection

[Acetronics2]

Hi,

The 16F628 has built in Comparators ... so, it's easy to get an interrupt if an input voltage goes under a choosen reference ...

till the regulator has sufficient supply, you can get some 5v absolute reference ...

Why not do it simple ???

Note a MC33064P5 can also do it ...

Alain

[Tywais]

A LTC1440 can do it and is what I use for one of my systems with 9V battery operation. It can operate with supply voltage from 2-11 volts. 2 resistors to set the trigger point and a on/off output that can be used to drive an LED or disconnect your power source from the circuit using either a relay or MOSFET.

[languer]

The IC Alain recommends, MC33064P5, is as simple as it gets. You still need to have some pass-thru device (transistor) between the supply and regulator, and the supervisor IC will enable/disable it based on the battery voltage. You can do the same with the MCU and external components (i.e. use MCU's comparator, external Vref, and pass-thru device).

[tazntex]

Thanks for all the suggestions. Using the comparator or the MC34064 both are great ideas, but wouldn't the just keep reseting? What I mean is applying the 9V battery to the input of the LP2950 5V regulator, and the powering the processor with the regulator having the MC34064 or the the processor on power up, code would start, compare the 9v battery is it above 6.2v or whatever if so, continue program, if not well, turn off a FET or transistor that would be in series with the 9v positive lead or ground leg, then once that happen let's see, wouldn't it start up again and do the same thing continuously?

Thanks again.