SurferTim:
@retrolefty: Now that I seem to have your attention on this, do you see a problem with IC7 if Vin > 10v? That would effectively overdrive the Vin input to IC7, would it not? Could that cause a latchup condition on the output?Just trying to figure out why it gets hot.
The op-amp input pin is wired to a voltage divider the cuts Vin in half to the pin. I don't know what the input pin voltage limit is for that specific op-amp, anyone have a datasheet link to it? But as the Vin limits are rated as:
Input Voltage (limits) 6-20V
That means the input pin of the op-amp is designed to work at up to 10v which is well above the Vcc the op-amp is powered by, so obviously the op-amp is designed to handle input pin voltage higher then it's running Vcc is. Again a datasheet is needed to see what the true voltage limit for the op-amp is. I think the op-amp specification we need to know is called it's input common mode rejection voltage rating?
Lefty