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TLV9002: TLV9002 VS SGM2358 Stand-by current

user5826658
Prodigy 10 points
Part Number: TLV9002
Other Parts Discussed in Thread: LM358,

Dear TI experts:
        My custom use lm358 for current detcet, however the product stand-by current was over limit.
so he consider use SG Mirco  SGM2358 and TI  TLV9002 replace.
compare both parameter, tlv9002 are all beter than competitors, But unfortunately the product stand-by current worse than competitors.
i was puzzled, the PCB are all the same, only p2p replace the amplifier.

TLV9002 Stand-by current:  4.86mA;
SGM2358 Stand-by current:4.45mA.
sch as following, the parameter can be optimization? thanks


  • 0
    TI__Guru**** 152666 points

    Hello,

    Over 4mA for this circuit seem very high. Is the current for the whole application (that includes more circuitry)?

    By standby, do you mean no input signal? If standby could be replaced by shutdown mode, that would help reduce the current draw by a lot.

     

  • 0 in reply to Ron Michallick
    TI__Guru**** 152666 points

    User,

    The typical currents per amplifier in the datasheet is LM358 = 300uA, SGM2358 = 400uA, TLV9002 = 60uA

    TLV9002 is the clear winner here. Yet, the measurements show otherwise. Is this repeatable?

    My guess is below as I don't know the actual voltages of any node other than the 5V supply (which is also assumed).

    <guess>If SGM2358 had a negative input offset error then the 0mV input would make output railed low, both outputs in fact. If an output rail low state causes the SGM bias current to drop dramatically then its quiescent could in theory be lower. A positive offset device would have a not zero 1st amplifier and all the current savings will be lost <\guess>

    In my experience some op amps have odd behavior (like bias current change) when used in "comparator mode", any nonlinear state. I don't know if that is the case here. Try adding a little negative bias to pin 6 (via a resistor) to get pin 7 higher than ground. Then check supply current again.

  • 0 in reply to Ron Michallick
    Prodigy 10 points

    Dear TI:

    yes ,it can repeatable.
    custom use the op amps in "comparator mode", can you give me more clean advice to improve the parameter.
    or tlv9002 is the right part  for this suitation. thanks

  • 0 in reply to user6187612
    TI__Guru**** 152666 points

    My best and easiest method to understand is to unsolder and lift pin 8 of the op amp for both designs and place a current meter between the 5V supply and pin 8 to see how much really flow through the op amps.