MCP1703 catastrophic failure under light load
Using voltage regulator MCP1703T-5002E/CB
Input voltage: 12V
Filter cap on output: 1u ceramic X5R 0603
The only load for this regulator is an analog VCO IC SSI2130:http://www.soundsemicondu...s/ssi2130datasheet.pdf
It draws about ~3mA and there is no crazy inrush currents on power up.
Problem: after about 30 seconds the MCP1703 fails by shorting the input to the output and thus delivering +12V to the SSI2130 (which is only tolerant to 5.25V) and then fries it. MCP1703 is then also permanently dead.
If instead use a 78L05 regulator there is no issue and the VCO IC is stable and works without fail.
What would cause such a catastrophic failure of the MCP1703? Why would it not just shutdown instead of shorting input to output?
Is the output cap so critical in value that if too small it is making the MCP1703 unstable and causes it to short out ?
The parts used were purchased from Digikey and I would hope/trust they are genuine Microchip parts.
We have used this same part in many past designs (not with this VCO chip) and they have worked ok.
Is this possibly a bad batch? or is it a known issue with this line of regulators from Microchip?