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DRV8872-Q1: internal pull down resistors

Lutz Naumann
Expert 6450 points
Part Number: DRV8872-Q1

Dear team,

DRV8872-Q1 has internal 100k pull down resistors on the input pins IN1 and IN2. What is the minimum and the maximum value we have to assume for this typical value of 100kOhm?

thanks

Lutz

  • 0
    TI__Guru** 114905 points

    Hi Lutz,

    The minimum value is in the datasheet under the Iih specification (Iih max = 100uA @ 3.3V or 33kOhms).

    Most queries are for the minimum value to ensure an external resistor can reach the proper Vih value.

    If you still need the maximum value, this will take a little more time to obtain. Please let us know if you need it.

  • 0 in reply to Rick Duncan
    TI__Expert 6450 points
    Thanks Rick,
    We are using a 5V MCU driving this pin. What do I use to determine the external drop resistor? With 100uA and 4,5Vmin supply the drop will be 3V to the Logic High Level. It results is a 30kOhm resistor. Assuming an external 27kOhm and the internal resistor is 33kOhm now this would result in 2.47V. If the supply goes high to 5,5V and the internal resistor is say 100kOhm+ you are coming closer to abs Max. = 5,5V. Will this be a valid condition over lifetime?
    thanks
    Lutz
  • 0 in reply to Lutz Naumann
    TI__Guru** 114905 points
    Hi Lutz,

    Yes, this will be a valid condition over lifetime.

    As you have done, it is best to assume a 30kOhm resistor when adding external impedance. This will ensure the device will see a logic high.