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TL072: Why the input current increase so much when configure TL072 as comparator

Vincent Zhang(BSR)
Expert 4795 points
Part Number: TL072
Other Parts Discussed in Thread: OPA196

Hi,

My customer meet one issue when I used TL072.

First, when they configure it as amplifier, it works normally. the input current is about 6mA.

When they configure TL072 as a comparator, the input current increase a lot and total pow loss increase to 0.68W, the IC is hot. But when they choose the JL412BPA , it works normally with same applications.

My questions is:

1. TL072 could be configured as comparator, right?

2. Any considering when configure as comparator?

3. What's the potential root casue?

Vincent Zhang

  • 0
    Guru 140200 points
    Hi Vincent,

    it's difficult to help, if the schematic is not complete.

    When omitting R42 the OPAmp can oscillate, if the voltage at the -input is similar to the voltage at the +input of OPAmp. The adding of a hysteresis can help then. Connect a high ohmic resistor in the MOhm range from pin 7 to pin 5.

    Another issue is that you violate the common mode input voltage range of OPAmp. You should decrease the input voltage, eventually by the help of a voltage divider.

    Kai
  • 0
    TI__Genius 15410 points

    Hello Vincent,

    What is the voltage at both input pins of the device configured as a comparator when there is an increase in current? It appears that it is 10V and 9.5V, which, as Kai mentioned, will violate the input common mode voltage of the device. The input common mode voltage on a +/-12V supply is +/-8V.

    The OPA196 is high voltage rail to rail input device that can be configured as a comparator. Can the customer use the OPA196?

    Thank you,

    Tim Claycomb