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TPS40210: Questions about over current

Kazuhiko Hirano
Genius 15088 points
Part Number: TPS40210

Hello,

My customer has some questions about over current as follows.

Q1: What is the configurable range of IOUT(OC) for the TPS40210DRC over-current threshold?

Q2: When used to boost the TPS40210DRC from an input voltage of Vin14.4V to Vout 37V, what current can the output current flow, taking into account the overcurrent operating point of the device?

Q3: What is the OCP response time? Previously, TI mentioned that the voltage drop across the shunt resistor will be detected immediately by the internal comparator if it exceeds 150mV and the response time will not be particularly long. Do you understand that the voltage drop across the shunt resistor exceeds 75ns of the TBLNK listed below?


Best regards,

K.Hirano

  • 0
    TI__Mastermind 30210 points

    Hello Hirano-san,

    Q1: The overcurrent threshold on TPS40210 can be set via the selection of the current sense resistor. To calculate the peak inductor current, please refer to our quickstart calculation tool:
    https://www.ti.com/tool/download/SLURB11

    Q2: The peak inductor current is dependent on load conditions and inductance. The calculator can be used for this as well. Please make sure the overcurrent limit is set high enough that it does not trigger during normal operation conditions

    Q3: As you mentioned, the OC has a blanking time at the beginning of each cycle to avoid false triggering due to diode reverse recovery.
    Regarding the delay between reaching the voltage threshold at ISNS pin and shutdown of the gate signal:
    There is an internal delay of 25ns typical.

    Please let me know if there are additional questions.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Genius 15088 points

    Niklas,

    Thank you for your responses, however my customer still has questions as follows.

    Q1/Q2:
    They would like to know the maximum IOCP current users can set. Datasheet Table 1 design example targets 3.5A IOCP at minimum. Users can set as much output overcurrent inception point as they want as the minimum with no maximum limitation?

    Q3:
    You mentioned there is internal delay of 25ns typical. And the datasheet specifies TBLNK is 75ns typical. So does this mean it takes totally 25ns + 75ns = 100ns?

    Best regards,

    K.Hirano

  • +1 in reply to Kazuhiko Hirano
    TI__Mastermind 30210 points

    Hi Hirano-san,

    Q1/Q2: There is no maximum current limit setting for the device. TPS40210 uses external power stage components (Inductor, MOSFET, diode).
    These components and the layout must be robust enough to support the peak current requirements.

    Q3: exactly. the 25ns would need to be added to the 75ns blanking time if OCP threshold is reached directly after turn-on of the MOSFET.
    Please note that the 25ns delay is the typical value, so there might be small variances from device to device.

    Best regards,
    Niklas