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LM5022-Q1: Dynamic response

Jiawei Hu1
Expert 5085 points
Part Number: LM5022-Q1
Other Parts Discussed in Thread: LM5022

Hi team,

My customer is developing a project with LM5022 which input is 8-18V, output is 25V, Iout is 0.6A. Attached is the schematic. The load of LM5022 is the LED driver TPS92630 with PWM dimming. As you can see, when PWM is high, LM5022 output has a voltage drop.

  • Customer wants the voltage drop should be less that 1V, how can we achieve that? How about making dynamic response quicker? How to adjust loop network?
  • Can you help review attached schematic to making dynamic response quicker?

SCHEMATIC1 _ DCDC.pdf

BR

Jiawei

  • 0
    TI__Mastermind 22100 points

    Hi Jiawei,

    I think the first possible solution is to increase the output capacitance value, if that is possible at all. That would be the easiest solution to solving your issues.

    Secondly, if that is not possible, then we should take a look at adjusting the compensation of the converter.

    By itself, the converter does not look very stable, as seen with the second image, so I would change the values as follows:

    C114 = 10nF; R361 ~ 800 Ohm; C409 ~ 146nF. This should give you a crossover frequency of 4.8kHz, and a PM of 77 degrees. You can utilize the power-stage designer calculation tool to also help in your calculations.

    Regards,

    Richard