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TLV2404: TLV2404

Gilbert De Guzman
Prodigy 20 points
Part Number: TLV2404
Other Parts Discussed in Thread: TLC27L9, LMC6044, TLC27L4

The TLV2404IDR output of the first op amp goes to rail (high) during low temperature (less than 10 degree Celsius).  Is there someone in TI that can help with this issue? 

  • 0
    TI__Mastermind 49956 points

    Hello Gilbert,

    Yes, we can help.

    Can you please provide more details (schematic, supply voltage, measured voltages, output load, etc), and preferably a scope photos and/or voltage measurements before and after the problem?

    Regards,

  • 0 in reply to Paul Grohe
    Prodigy 20 points
    Sorry Paul, I cannot provide you the schematic. If you have an FAE and can come to our facility, I can show him/her the things you needed. I can also tell you that I changed the op amp with Linear Tech: LT1491 and the problem went away.
  • 0 in reply to Gilbert De Guzman
    TI__Expert 6030 points
    Hi Gilbert,

    Thanks for the phone discussion on this issue. We'll work this offline and will update this post if needed.

    Phil
  • 0
    TI__Mastermind 49956 points

    Hello Gilbert,

    Looking at the schematic and scope photos, most likely it is due to the fact that the TLV2404, which is a nano-power (900nA) op-amp, just cannot drive the feedback and output loads.

    It has a very "weak" output stage (200uA max). It cannot drive "normal" ~20K loads full swing (and feedback resistors count as a load). Nano-power amplifiers are expecting feedback resistors and loads in the meg-ohm range (to minimize power dissipation in the feedback).

    If you look at the output sink/source graphs in figures 15 and 16, you can see that the current limit kicks in at about 80-150uA at cold (worse sinking). Output drive drops with temperature. You are probably on the edge of operation and seeing the device-to-device variation.

    The LT1491 is a much higher power amp (10uA), and is capable of sink/sourcing several mA.

    Is there a particular reason you chose the TLV2404 - other than a micro power 12V quad?? The resistor sizes do not suggest a micro-power application.

    Looks like you do not need R-R Input, so have a look at a device like the TLC27L4, TLC27L9 or LMC6044 - as these are <20uA and can drive several mA.

    Regards,

    Paul Grohe