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ISO7710: Behavior during start-up

Part Number: ISO7710

Dear Team,

our customer would like to use the ISO7710 in an input module. The front end is powered from the input, meaning that is turning on and off. The output / the other side @ VCC2 is constantly on.

I saw in the referred post, that the output could be giving some pulses during the start-up because the default out is HIGH. So as per my understanding, it might be better to use the F version to have LOW in those situations.

Could you please confirm that this is not a problem?

Is there any risk of having spurious glitches or any starting oscillation if VCC1 is ramping slow?

Do you also have more information about the start-up time? I saw in another post that the max. start-up time is 180us. Do we have a typical value for this?

Thanks and best regards
Martin

  • Hello Martin,

    thank you for using TI E2E.

    Just to make sure I understand you correctly:

    In your descirbed cenario, VCC2 is on and VCC1 will ramp up. How is IN1 conneceted? Will it be low during the startup or ramp up with VCC1?

    Do you also have more information about the start-up time? I saw in another post that the max. start-up time is 180us. Do we have a typical value for this?
    I can give you a better estimate of startup time in your specific conditions. 180us is the abs max. If you can give me some details on the supply voltage, ramp time and ambient temp, I can get you a estimation of the startup time.

    Best Regards,

    Matthias

  • Matthias,
    thanks a lot for the support.

    Quickly summarizing what we discussed off-line: No glitches are expected when VCC1 ramps up.
    Confirmed that if VCC1 ramps up (condition: VCC2 = PU and IN = LOW), the output stays in default state. In case of ISO7710 this is default HIGH. The ISO7710F has default LOW.

    Best Regards
    Martin