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Regulation of TPS76201 LDO

Abdul Dahche
Prodigy 30 points
Other Parts Discussed in Thread: TPS76201, TPS84621

Hello,

I use in our application the TPS76201 LDO regulator. I want to regulate the LDO with a 10K ohm digital potentiometer in the range of 0.7 V to 5.5 V (VOUT - 10K digital poti - GND). According to the datasheet are Low resistors in the feedback-pin allowed. But when low resistance regulates the LDO, I don't have a high resolution (50mv resolution nedeed) or the LDO dont work properly. And by high resistance the ldo have a high resolution. Works the TPS76201 linear? Can you suggest us, or a Alternatively LDO?

Thanks.

  • 0
    TI__Mastermind 40100 points

    Hi Abdul,

    Would it be possible to use a 66.5k Ohm resistor on R2 and a potentiometer for R1? This way you keep the amount of divider current the same.

    If you want to use higher resistances, you must choose an LDO that has lower feedback current to maintain the specificed accuracy of the device. We can certainly help you choose an LDO that might fit your application. What are your power requirements?

  • 0 in reply to Darwin Fernandez
    Prodigy 30 points

    Hi Darwin,

    yes i can use a 66,5k Ohm resistor but the R1 digital poti must be 500k Ohm. Such digital poti are rare to find.

    here the power requirements:

    input voltage: 5,5V

    output voltage: 0,7V to 5,5V

    current: min. 100mA

    Thank You.

  • 0 in reply to Abdul Dahche
    TI__Expert 7589 points

    Have you considered connecting a DAC to the bottom part of the R2 resistor and set the VDAC voltage to get the desired VOUT. Using the VDAC you can get really good resolution on VOUT even <1mV.

    I had used this approach on TPS84621 to set the VOUT from 0V/2.5V. I was able to program my VOUT in steps of 1mV. I would check with the product apps engineer to see if connecting a VDAC would give a stable and more accurate solution.

    Regards,

    Arjun

  • 0 in reply to Arjun_Prakash
    Prodigy 30 points

    Hi Arjun,

    No, i dont have connecting a DAC to Feedback. Because my system power supply is 3,3V and the DAC of the µC can give a DAC VOUT of max. 3,3V.

    And i would not connect more Hardware like OPV in the design.

    Regards,

    Abdul

  • 0 in reply to Abdul Dahche
    TI__Mastermind 40100 points

    Hi Abdul,

    The TPS76201 is the best IC that fit your application becase of its low output voltage capability and adjustable output. One other option is to use multiple digital pots in combination to achieve the desired resolution but this will probably require more control circuitry.