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4 years, 2 months ago.
I have a situation where I am restricting the voltage imput from 7V to 30v. If voltage drops below 7V my buck convertor (TPS54240) will cut off power to device. If it goes over a 30v spike my varistor will cut off the device.
So heres the problem: When the voltage drops below 7V to say 6 and then comes back to 7 the micro controller doesnt start. If i remove the device and plug it back in it works in some cases. If i "short the power and earth" in the device to take care of any residual capcacitance it always works wheen i put it back in
I have 2 1mF on the output side of the buck convertor and am guessing that is holding the power and the micro controller is stuck in some state. To prove this connected a TTL to see if micro controller is dong somehting. However when TTL is connected it works correctly as expected. Guessing the TTL is continuing to provide some power or is draining power causing the MCU to have a "clean break"
Can anyone throw some light? After this rambling :)
Best Regards Suerndar