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TPS560200 Buck Converter Potential stability issues

Kirubananth Chinnathambi
Prodigy 10 points
Other Parts Discussed in Thread: TPS560200

I build my circuit by using TPS560200 buck converter for ESP8266 power 3.3v. but i am facing potential stability issues.
after connecting of all components as per datasheet mentioned.

I am getting 1.0332v while build for initial testing circuit.
after i connected the 61.9k at R1 and 20K for R2. then i found the potential stability issues.

i mean it can give 3.4v and drop down to 0.34v.
i am not getting proper output whatever i am expecting.

Please help me!!



  • 0
    TI__Expert 8436 points

    Hello,

    Please share your schematic with us so that we can review and provide feedback

    Best regards,

    Britton

  • 0 in reply to Britton Jones
    Prodigy 10 points

    in this, I used 61.9k ohm for 3.3v output instead of 6.19k fro 1.0v rest of the circuit is same as.

  • 0 in reply to Kirubananth Chinnathambi
    TI__Expert 8436 points

    Your schematic is configured correctly, but you can improve stability by populating a feed-forward capacitor at C5. 

    The value of this capacitor can be optimized using the equation below where fco is the unity gain crossover frequency without the external feedforward capacitor, R1 is the top resistor and R2 is the bottom resistor in the feedback resistor divider.

    If this does not improve things, please share your board layout, bode plots. and output waveforms so that we can investigate this further. 

    Furthermore, it sounds like the issue did not appear when R1 was configured with 6.19k but only became an issue when R1 value was changed. If this is true, please double check solder at R1 and trace connections back to VSENSE.