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TPS7B4253-Q1: tps7b4253-q1 voltage clamp function

John Rice
Prodigy 430 points
Part Number: TPS7B4253-Q1
Other Parts Discussed in Thread: TINA-TI

Can I use this device to track the input up to a specific level and then regulate at that level?  Application is in powering a sensor with a max voltage of 30V.  If load dump is 34V I'd like to use this device to power the sensor through load dump.  The regulator would track VIN up to 27V and then regulate the output to 27V.  I think I can use the FB pin and ADJ pin as illustrated in the attached TINA-TI file.  Please confirm.  Thank you, JohnTPS7B4253_v9.tsc

  • 0
    TI__Mastermind 23361 points
    Hi John,

    I am having trouble openning your Tina file, will you check and upload it again?

    Regards,
    Jason
  • 0 in reply to Jason Song
    TI__Prodigy 430 points

    Hi Jason,

    Try this.  Here is an image of the file in case you can't read it.

    5383.TPS7B4253_v9.tsc

  • 0 in reply to John Rice
    TI__Mastermind 23361 points
    Hi John,

    The .tsc file you attached to the thread stil won't open on my end and thanks for sharing the screenshot of the schematic.

    Please see my comments with your questions:
    1. Can I use this device to track the input up to a specific level and then regulate at that level?
    The tracking LDO is designed to track the voltage on the ADJ pin, not input pin.

    2. Application is in powering a sensor with a max voltage of 30V. If load dump is 34V I'd like to use this device to power the sensor through load dump. The regulator would track VIN up to 27V and then regulate the output to 27V. I think I can use the FB pin and ADJ pin as illustrated in the attached TINA-TI file. Please confirm.
    The regulator can be used for tracking and regulating, but the voltage it's trackign to needs to be from the ADJ pin. ADJ pin, however, has a maximum voltage of 18V, if 27V is needed, a gain needs to be set using R1 and R2 like the ones showed in your schematic.


    Regards,
    Jason
  • 0 in reply to Jason Song
    TI__Mastermind 23361 points
    Hi John,

    Actually, if you have the 2.5V on ADJ pin before starting ramping Vin; after Vin passes UVLO voltage. Vout will start going up with Vin as your simulation shows. If you have a load on Vout during the ramp, the difference between Vin and Vout will be the dropout value at the load. Hope this helps.

    Regards,
    Jason Song