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TPS544B20: TPS544B20 switching frequency

K. Sasaki14
Guru 10200 points
Part Number: TPS544B20

Can TPS544B20 operate at 1MHz switching frequency?
I changed RT resistor to 360 kohm. However switching frequency was 700kHz.

Best Regards,
Kohei Sasaki

  • 0
    TI__Guru**** 191445 points
    TPS544B20 should be able to operate at 1 MHz. According to the datasheet, the RT required for 1 MHz operation is 205 kohm.
  • 0 in reply to JohnTucker
    Guru 10200 points

    John-san,

    I'm understanding datasheet description.

    However there is the following description on datasheet P.20,
    "the device selects a frequency setting of either 250 kHz (if the resistance is less than 5 kΩ) or 1 MHz (if the resistance is greater than 300 kΩ)."

    From this, I think TPS544B20 switching frequency becomes 1MHz with 360k ohm.
    It was about 700kHz when I set RT resistor to 205k ohm too.
    Have you checked 1MHz switching frequency operation?

    Best Regards,
    Kohei Sasaki

  • 0 in reply to K. Sasaki14
    TI__Guru**** 191445 points
    I have not personally checked it. I only looked at the datasheet Electrical Characteristic Table. Let me forward this to someone who maty have looked at it. Otherwise it will be mid- January until I can check it.
  • 0 in reply to JohnTucker
    Guru 10200 points
    John-san,

    How is the progress about this?

    Best Regards,
    Kohei Sasaki
  • 0 in reply to K. Sasaki14
    TI__Prodigy 580 points

    Hi, Sasaki-san,

    During the validation of the part, one of my colleague validated the 1MHz operation of this device. So it was tested.

    For the issue you have, I would suggest check the operating frequency with different load as first step. Then check the operating frequency again when RT resistor is removed.

    As specified in the datasheet, when the detection circuitry detected RT resistor is higher than 300kHz, the device would set operating frequency to 1MHz.

    Best regards,

    Ray Chen

  • 0 in reply to Ray Chen
    Guru 10200 points

    Chen-san,

    Thank you for your answer.
    I tested again, and I confirmed Fsw becomes faster as load current increases, it became within spec.

    So I would like to ask you a question about Fsw of datasheet characteristic.
    How did you test the switching frequency?

    Best Regards,
    Kohei Sasaki