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Problem of TL074's 0V input

Satoshi
Guru 19485 points
Other Parts Discussed in Thread: TL074

TL074's supply voltage timing is "Vcc+:15V → 5ms delay → Vcc-:-15V" because of customer reason.

Is it no problem?

Is there problem and inprovement point, please let me know.

Concern point is below.

・Common Mode Input Votage Range：±11V_min,

  When supply only Vcc+:15V, Input voltage range is 4V～11V.

　I think that TL074 will error on VIN:0V.

・In the past, the other OPAMP used only Vcc+:15V,

　VIN:0V supply became nearly -15V.

　I worry about whether the same thing will happen.

Best regards,

Satoshi

  • 0
    TI__Guru*** 139906 points
    Satoshi san,

    It is highly recommended that no inputs are shorted to ground. A series resistance on the inputs is high recommended.
    The reason is that the -15V might become positive during power up or power down sequence.
    A grounded input might have high input current when -15V supply is positive voltage.

    During the time that only +15V is present, the device may or may not be performing to application design depending of things like input common mode range. Once the -15V also comes online then normal operation should begin.
  • 0 in reply to Ron Michallick
    Guru 19485 points

    Ronald-san

    Thank you for reply.

    Sorry for addition, please let me know three point below on problem case (timing:15V→-15V).

    ①I think that the route of inlush current is "VCC- ⇒ IN-", is it correct?

    ②When circuit is voltage follower, is it problem,too?

    ③Can internal resister (please see below) moderate this problem?

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Guru*** 139906 points

    Satoshi san,

    The VCC- to IN diode is parasitic and shown in green. This is the current path.

    The reason that input must be >4V more positive than VCC- is shown in blue.