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UCC28700-Q1: Peak Current Sink?

Part Number: UCC28700-Q1

Team,

I am helping a customer with worst case analysis and a question came up on the gate current sink spec. Should a gate resistor be used to limit the sink current when the Fet driven is being turned off since the abs max  continuous gate current sink is 50mA? Is there a recommended maximum peak current sink spec?

  • Dear Julio,

    Thank you for reaching out to us.
    Basically, a gate resistor is necessary.
    Igate=VGate/(Rsource+RGATE+Rg)
    It is easier for us to control the Igate by adjust the RGATE resistor, no matter is for EMI concern or current spike during turn on.

    Just like you mentioned, the IC's maximum gate sink current is 50mA. The Abs Max specs are continuous DC ratings, just make sure the sink current won't over 50mA continuously is enough.
  • Hello Julio,

    As Kuan Wei mentioned, the Abs Max rating is a limitation to 50mA of continuous DC sink current. It does not apply to normal peak switching current. There is no peak current specification, but the controller internal gate-drive structure is self-limiting to approximately 400mA peak sink current when driving a MOSFET gate. This is the normal and expected load (capacitive) for the driver, and normally does NOT require any specific gate resistance value to limit to < 50mA peak. RGATE may be used and adjusted to avoid high-frequency ringing or to limit turn-off dV/dt, if necessary.

    It would be an unusual application that would require continuous currents from the gate-drive stage, but such an application is acceptable provided the continuous sink current is less than 50mA and the controller junction temperature is maintained below 125C for in-spec operation.

    Regards,
    Ulrich