I am working with a current source circuit that produce 10mA current in frequency range between 10kHz to 100kHz. After fabricated the circuit I perform some tests on the circuit and all the output produced accordingly. However after some time, I noticed some of the ics LM6172 (u1,u2,u3) produce some heat (warm) during operation.Is this normal? Even worse I also noticed the LM7171 (u4) is extremely hot after several seconds (approx.15 seconds) from the time the circuit is turned on. I know this this is not normal so I performed some quick check on the circuit. This is what I've done:
a) check for short connections between +15V and -15V - no short connections found
b) check any failure components (capacitor) - no failure found.
I truly hope the members in this board can help me to resolve the problem. Any advice or ideas are highly appreciated. Thank you in advance.