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TIC10024-Q1: Switch to battery - 12 V test pulses ISO 7637-2 support

Luca Favario
Prodigy 50 points
Part Number: TIC10024-Q1
Other Parts Discussed in Thread: TIC12400-Q1

Hello,

I am planning to use the TIC10024-Q1 in a 12 V automotive ECU.

I want to connect 10 switch to 12 V battery to pins IN0-IN9 of the TIC10024-Q1.

Does the TIC10024-Q1 support test pulses from ISO 7637-2 on its input pins IN0-IN9 without additional external circuits (TVS, diode, resistive divider)?

I have seen the application note "Protecting 12-V MSDI Devices in a 24-V System", but it is dedicated to 24 V systems.

I assume that a TVS and a diode are mandatory to protect the TIC10024-Q1 from voltage transients even in 12 V systems, but this solution limits the flexibility of the MSDI.

Thank you in advance,

Luca

  • +1
    TI__Mastermind 26840 points

    Hi Luca,

    Luca Favario said:
    Does the TIC10024-Q1 support test pulses from ISO 7637-2 on its input pins IN0-IN9 without additional external circuits (TVS, diode, resistive divider)?

    No, external filter components are required to support ISO 7637-2 pulses.  Based on some internal testing, a shunt filter cap of 15nF and a series resistor of 180 ohms allows Level III 1, 2A, 2B, 3A, and 3B pulses to pass.

    With a 220 ohm series resistor the Level IV 1, 2A, 2B, 3A, and 3B pulses passed 50% of the time.  When we added a TVS diode (US1D-E3/61T) to the 220 ohm resistor and 15nF cap, Level IV pulses passed.  Other diodes can be used, this is just the one that was used in our testing for your reference.

    Also note the device ESD ratings are also dependent on the presence of external caps and resistors on the INx pins.  See the TIC12400-Q1 and TIC10024-Q1 ISO-10605 ESD Test Report (Link)

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 50 points

    Thank you Jonathan.

    To clarify about Level IV pulses:

    • did you use a TVS diode (e.g. SMBJ36) in parallel with the input or a series/clamping rectifier diode (e.g. the US1D-E3/61T you mentioned)? Could you share the circuit?
    • did you have trouble supporting positive or negative pulses without the diode?
    • is a report available for these tests?

    Regards,

    Luca

  • 0 in reply to Luca Favario
    TI__Mastermind 26840 points

    Hi Luca,

    Luca Favario said:
    did you use a TVS diode (e.g. SMBJ36) in parallel with the input or a series/clamping rectifier diode (e.g. the US1D-E3/61T you mentioned)? Could you share the circuit?

    I was not personally involved with this testing, and it was performed many years ago, but the report summary does not mention the use of an additional series/clamping rectifier diode.

    Luca Favario said:
    did you have trouble supporting positive or negative pulses without the diode?

    The report summary does not indicate positive vs. negative pulse results, but simply states that it passed the Level IV pulses 50% of the time with the 220 ohm resistor and NO TVS diode, but 100% of the time with the additional TVS diode.

    Luca Favario said:
    is a report available for these tests?

    I will follow up with you through email with the report summary that I have for this testing.

    Regards,

    Jonathan

  • 0 in reply to Jonathan Nerger
    Prodigy 50 points

    Thank you again for your valuable feedback.

    Regards,

    Luca