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TIC12400: Will the voltage drop of diode D1 affect the acquisition of ground signal

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Part Number: TIC12400

Hi Team,

When using TIC12400 in 24V automotive system, here meets a question.

When the configuration is grounded, if K2 is switched on, the current flows through D1 from SPI IN0.

When the configuration is power supply, K1 is switched on, the current flows through D2 to SPI IN0.

The transient voltage of the power supply of 24V system is lower than the clamping voltage of TVS tube of 12V system after the clamping voltage of RP1 and TVS1.
And the resistance of 1K at the rear stage can basically ensure the safety of the voltage at SP1_IN0.
One of the problems in this design is: will the voltage drop of diode D1 affect the acquisition of ground signal?

Thanks a lot!

  • Amelie,

    The voltage drop of D1 will affect the acquisition of the ground signal by creating a voltage drop when the TIC12400 sends out its wetting current.  This shouldn't be an issue unless there is something else going on like ground shifting because the lowest comparator threshold is 2 V and you can set the threshold up to 4 V to give your system more margin.  

    Thank you, 

    Adam

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