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UCC21520-Q1: About INA and INB input current

Tsukui Yusuke
Guru 21930 points
Part Number: UCC21520-Q1


Hi,

Could you tell me the input current specifications of INA pin and INB pin?
The driving condition is 200kHz to 700kHz.
Customers want to know how much input current INA pin and INB pin need.

Best Regards,
Yusuke

  • 0
    TI__Guru**** 189401 points
    Hi, Yusuke-san, Those pins are connected to high impedance CMOS circuitry with TTL-compatible thresholds. The apps engineer for this device is out for the US holidays. He will be back next week and will work with you on this question.
  • 0 in reply to Don Dapkus
    Guru 21930 points

    Don-san,

    Thank you for your support.
    I understand  the situation.
    We look forward to hearing from you.

    Best Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Expert 3355 points

    Hi Yusuke-san,

    These input pins have an integrated pull-down resistor which is nominally 200kΩ.

    The peak input current will be approximately Iin = Vin/200k.

    The average input current will scale with duty cycle, approximately Iin(avg) = Vin/200k*D.

    If this answered your question, could you please press the green button? If not, feel free to ask more questions.

    Thanks and best regards,

    John

  • 0 in reply to John Geiger
    Guru 21930 points

    John-san,

    Thank you for your support.
    Let me know one more thing.
    Could you tell me the input impedance of the buffer with hysteresis?
    Customer thinks this impedance contributes to input current.



    Best Regards,
    Yusuke

  • 0 in reply to Tsukui Yusuke
    TI__Expert 3355 points

    Hi Yusuke,

    The input buffer is CMOS based and designed for minimum input capacitance. It does not add significant input current at these frequencies, compared to the input current from the 200k pull-down. I will typically assume input pin capacitance is ~1pF for these types of logic level inputs.

    If this answered your question, could you please press the green button? If not, feel free to ask more questions.

    Thanks and best regards,

    John