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TCAN1043-Q1: Rdson between Vsup and pin 7 (INH)

May
Genius 9880 points
Part Number: TCAN1043-Q1

Hi Team,

I've received a query from customer, looking for the Rdson of the FET switching between Vsup and pin 7 (INH). Can you provide an independent value for Rdson or the charactersitcs of it (based on voltage, curent)?

Thank you and looking forward for your response.

Regards,

Maynard

  • 0
    TI__Guru 62920 points

    Hi Maynard,

    This is specified indirectly via the INH output voltage specification.  The datasheet specifies a typical voltage drop of 500 mV from VSUP to INH when the load current is 0.5 mA, which suggests the typical switch resistance is 1000 Ohms.  Please let me know if this isn't clear or if you have further questions.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    TI__Genius 9880 points

    Hi Max,

    Thank you for your response.

    The customer want the independent value of the Rdson. Below is the inquiry of the customer.

    Thank you for the information. The problem as far as I understand is, that this maximal 2k Rdson value is true only in case of 0.5mA current, I am calculating an inrush current through this pin, because the INH is connected to Vsup (worst case it can reach 35V) via this inner FET that appears in the datasheet and there is a 15nF capacitor between INH and ground in our circuit. So there will be a large inrush current that's peak will be limited only by the ESR of this capacitor and the Rdson on the inner FET but for sure larger current will flow there than 0.5mA so can you please provide an independent value for Rdson or the charactersitcs of it (based on voltage, curent)

    Looking forward for your response. Thank you!

    Regards,

    Maynard

  • 0 in reply to May
    TI__Guru 62920 points

    Hi Maynard,

    Thanks for the background.  If they are calculating the maximum inrush current, they would need to know the minimum Rds(on).  In this case I would use 180 Ohms as the value.  That is the lowest I would expect it to go when accounting for variation from unit to unit, temperature, supply voltage range, etc.

    Max

  • 0 in reply to Miguel Robertson
    TI__Genius 9880 points

    Hi Max, 

    Thank you for this information. 

    Regards,

    Maynard