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TL074A: how to connect the pins of un-use channel

Sean ZHang35753
Intellectual 2060 points
Part Number: TL074A
Other Parts Discussed in Thread: TL074

Hi,

Customer just used 3 channels of TL074, and connected the rest channel input and output together with GND, please refer attachment for the schematic.

Now, customer reported about 30% TL074 will be very heat up to 90C, but change it to a new one, then the temperature is normal about 50C.

Could you please comment if it is ok to connect together to GND? also please advise what's potential problems to cause over heat.

Best Regards

  • 0
    Guru 140200 points

    Hi Sean,

    the cause of heating up is the short of output to signal ground.

    The best way to handle an unused OPAmp here is to connect the +input of OPAmp to signal ground and to connect the -input of OPAmp to the output of this OPAmp. This forms a voltage follower (non-inverting amplifier with a gain of 1).

    Kai

  • 0 in reply to kai klaas69
    TI__Guru*** 142726 points

    Sean,

    Follow Kai's advice but add a 10k series resistor between ground and non-inverting input. This protects the input in case there is a power supply fault that makes VCC- positive voltage.