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TPSM82902: TPSM82902 variable output voltage support

Sanjay
Expert 5870 points

Part Number: TPSM82902

Tool/software:

Hi Team,

As the details below - it supports discrete and fixed VOUT voltage as per the R2 selection. 

Does this part supports dynamic and continuous VOUT vs VSET ? Can I bias the VSET node with a variable voltage directly or through the resistor bias?

Thanks,
Sanjay

  • 0
    TI__Genius 11730 points

    Hi Sanjay, 

    Instead of Vset; you can use the regular FB functionality with DAC input to control Vout. Here are few links you can refer: 

    (+) TPS40345: variable voltage output with TPS40345 - Power management forum - Power management - TI E2E support forums

    How to Design a Variable Output Buck Regulator

    Regards,
    Gautam

  • 0 in reply to Gautam Iyer
    TI__Expert 5870 points

    Hi Gautam,

    Thanks for the response. But I am aware of the DAC based design and it's not what i am asking here.

    In the TPSM82902 data sheet section 7.3.3  Selectable Vo Operation  -  it says fixed and discrete output configurations with just one resistor R2 only. What i want to know is this - 

    1. Does this part supports dynamic and continuous VOUT if i add a variable resistor instead of R2?
    2. Can I use a DAC output and connect to the FB directly to control the output of the DC/DC module. If not - 
        a. Can I bias the R2 only and use a DAC output by connecting to the R2 GND node directly to control the output of the DC/DC module.

    I hope I am clear with my queries here.



    Thanks,
    Sanjay

  • 0 in reply to Sanjay
    TI__Genius 11730 points
    Sanjay said:
    1. Does this part supports dynamic and continuous VOUT if i add a variable resistor instead of R2?

    Nope, only at start-up. 

    Sanjay said:
    2. Can I use a DAC output and connect to the FB directly to control the output of the DC/DC module. If not - 
        a. Can I bias the R2 only and use a DAC output by connecting to the R2 GND node directly to control the output of the DC/DC module.

    I'm not aware of any such configuration. I guess the best way to confirm the same is by simulating using PSpice model. 

    Regards,

    Gautam

  • 0 in reply to Gautam Iyer
    TI__Expert 5870 points

    Gautam,

    Thanks. This means, I can't use a R2 as variable resistor to change the output. 

    2. Can I use a DAC output and connect to the FB directly to control the output of the DC/DC module. If not - 
        a. Can I bias the R2 only and use a DAC output by connecting to the R2 GND node directly to control the output of the DC/DC module.

    I'm not aware of any such configuration. I guess the best way to confirm the same is by simulating using PSpice model. 
     

    Can you please just check with design or test and confirm if this particular configuration is supported or not ? No simulation is needed here.

    Thanks,
    Sanjay

  • 0 in reply to Sanjay
    TI__Genius 11730 points
    Sanjay said:
    Can you please just check with design or test and confirm if this particular configuration is supported or not ? No simulation is needed here.

    Not possible. Both the options are not possible. The only option is as mentioned in the App note: How to Design a Variable Output Buck Regulator 

    Regards,

    Gautam