LMR51420: Ringing during transient load change

My-Linh Nguyen

Part Number: LMR51420

Hi,

I'm currently designing a boost converter around the LMR51420. Output current = 0.9A, L = 10uH, COUT = 2x22uF, R1 = 100k, R2 = 13.7k.

It seems that when the load is changed from 0 to 0.9A, there is a large spike (5.3V, usually voltage is at 5V). Is there a way to minimise this by adding a feedforward capacitor? There doesn't seem to be any guidance in the datasheet. Would you be able to suggest how I can remedy this?

Thanks!

over 2 years ago

0 Aurora Tie over 2 years ago

TI__Genius 16680 points

Hi,

During the load transient test, the change value of the output voltage ripple is related to the loop speed. Generally, the faster the loop, the smaller the peak value of the Vo_ripple. For the converter, this situation can be improved by adjusting the feedforward capacitor or increasing the output capacitor. For the adjustment method of the feedforward capacitor, please refer to AN in the attachment. Hope this can help you. Thanks.

Design Feedforward Capacitor for LMR14020.pdf

Optimizing Transient Response of Internally Compensated DC-DC Converters.pdf

Aurora

0 Aurora Tie over 2 years ago

TI__Genius 16680 points

Hi,

I will close this thread due to no reply for a long time. If you have other questions in the future, you can ask them again in E2E. Thanks.

Aurora

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LMR51420: Ringing during transient load change