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TPS62871-Q1: Loop stability

Rasathi Subramaniam
Prodigy 30 points
Part Number: TPS62871-Q1

Tool/software:

Hello Team, 

I am using this as single device operation, and trying to measure the loop stability. The Vout is given as feedback to VOSNS. Is this the point to inject the noise? Please refer to image below.

 

  • 0
    TI__Genius 17401 points

    Hi,

    Yes, the connection is correct on image for stability analysis. I would suggest to use 5/10Ohm resistor value.

    Let me know if you need further information on set up.

    Best regards,

    Tanvee

  • 0
    Prodigy 30 points

    Hello Tanvee,

    Thank you for prompt response. Please find the below images for stability measurement under different temperatures. At -40degC, the PM and GM is less than the expected. Could you please review these? I am yet to perform with 7.5A load. Will update you.

    25degC, 2A load:

    -40degC, 2A load:

    85degC, 2A load:

  • 0 in reply to Rasathi Subramaniam
    TI__Genius 17401 points

    Hi Rasathi Subramaniam,

    Thanks for sharing the measurements. Are you doing measurement son TI EVM or on your board?  If its your board could you share schematic and layout ?

    Just want to know the output voltage as -17dBm would be higher noise to inject you can even go lower to -25dBm to -30dBm. That's the reason may be sudden drop on the gain plot in room temp.

    Best regards,

    Tanvee

  • 0 in reply to Tanvee
    Prodigy 30 points

    Hi Tanvee,

    Please find the schematic and layout images below:

    ok, i will try to measure it again in room temp.

  • 0 in reply to Rasathi Subramaniam
    TI__Genius 17401 points

    Hi Rasathi Subramaniam,

    Thank you for sharing it. Your operating condition is 3.3Vin, 1Vout and maxi load is 7.5A?

    Could you share max load or step profile? It will help to check on capacitor bank and compensation resistor selection. In -40 deg, capacitor would degraded most and that is impacting lower PM. 

    Best regards,

    Tanvee

  • 0 in reply to Tanvee
    TI__Genius 17401 points

    Hi,

    I am closing thread. Feel free to open once you have more information.

    Thanks,

    Tanvee