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TPS40210-Q1: Dynamic configuration of Feedback resistance

NOBUO FUJIHARA
Genius 9345 points
Part Number: TPS40210-Q1
Other Parts Discussed in Thread: TINA-TI, TPS40210

Hi Champs,

My customer would like to control Vout from 36V to 50V by switching Feedback bottom resistance dynamically.

I simulated this behavior by TINA-TI which is imported from Webench, but when changing resistance switching itself stopped.

I attached TINA-TI simulation model, and I suppose this unexpected termination appear only in TINA-TI simulation.

Q.1) Can you check whethr TPS40210 could support this method of change Vout from 36V to 50V by switching Feedback resistance?

Q.2) Can you provide expected period it take for output 36V to be settled to 50V?

Best regards,

Nobuo Fujihara

TPS40210_webench_design.TSC

  • 0
    TI__Mastermind 21720 points

    Hi Fuijihara,

    Q.1) Can you check whether TPS40210 could support this method of change Vout from 36V to 50V by switching Feedback resistance?

    Using switches to modify the output voltage should be fine with some slight modification. I would suggest using one switch, removing SW2, always having R1 connected between FB and GND. This way no matter what the output voltage is set to 36V. When the output voltage needs changed only SW1 will need to be toggled on or off. Then RFB1 should be changed to 2.85kOhm. When SW2 is closed this will result R1 and RFB1 being in parallel and having an equivalent resistance of 734Ohm, setting the output voltage to 50V.

    Q.2) Can you provide expected period it take for output 36V to be settled to 50V?

    This is will depend on quite a few of the components such as; Output capacitance, current limit, compensation selection, VIN and many more. Ramping the voltage from 36V to 50V will be faster than ramping down from 50V to 36V as the TPS40210 is non-synchronous. After making the above changes for the it should be possible to simulate to come up with a good idea of the rise and fall time. 

    Please contact me directly if you have any more questions or issues.

    Thanks,

    Garrett

  • 0 in reply to Garrett Roecker
    TI__Genius 9345 points

    Thanks Garrett, I will contact you directly.

    Best regards,