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LMV341: Glitch noise after nSHDN Low to High

Part Number: LMV341

Hello,

Our customer use the LMV341.

For reduce a current consumption, the customer use a shut down function.

When the customer de-assert the nSHDN pin, there is a glitch noise as follows.

LMV341_glitch.pdf

A glitch level is related to temperature.

Could you tell me what is the cause?

Best Regards,

Naoki Aoyama

  • Naoki-san,

    When coming out of shutdown, the amplifier circuit is not running closed loop (settled). The op-amp may overreact to close the loop; it depends highly on the passive components in the loop. If the input voltages are initially out of common mode range then the op-amp may make the wrong initial decision.

    There are 3 different LMV341, do you mean LMV341, LMV341-N, LMV341-Q1?
  • Hello Ron,

    Thank you for your reply.
    I heard the customer use the LMV341.
    An application of the customer is I-V convert for photo diode.
    It may be floating when in shut down.

    Is the characteristics 'turn on time' related to temperature?

    Best Regards,
    Naoki Aoyama
  • Naoki,

    I checked a simple unity gain setup, VCC 5V, VIN 2V, Output load 10M ohms and about 50pF

    My results did not vary much with temperature and power up was much faster the data sheet typical.

    When you tested temperature, are all components  subject to that temperature?

    25C

    -40C

    125C

  • Hi Ron,

    Thank you for your reply and evaluation.
    I see the turn on time is not related to temperature.
    If the customer can not avoid a glitch noise, I will suggest the customer
    to use a very low supply current Opamp.

    Thanks,
    Naoki Aoyama