Output Ripple DC/DC

[Snir123]

Hi all,

I have observed a phenomenon in my new design where the ripple is significantly large at light loads but decreases to very low levels when the load increases to its maximum.

I have attempted to change the frequency and add additional capacitors, but these measures have not resulted in any improvement.

I am seeking to understand the cause of this behavior. Could someone provide assistance with this issue?

 

Thank you in advance.

 

[Peter BENSCH]

Welcome @Snir123, to the community!

Thank you for your confidence that the community of STMicroelectronics could help you with a problem with a TI switching regulator. However, it might be more successful if you ask in the TI forum?

Good luck!
Regards
/Peter

[Muhammed Güler]

I recommend that you make calculations for the minimum and maximum current value when choosing coils and capacitors in SMPS.
SMPS operates in continuous mode under load, and in discontinuous mode if the load is light.

In discontinuous mode, SMPS tries to keep the voltage at the desired level by skipping PWM pulses.

This situation is probably causing the problem you are experiencing.

You can try using higher value inductors and capacitors, use multiple SMPS or use ferrid beads to isolate the sensitive circuit area.

If you are experiencing this problem in a scenario where the load draws no current, you may even consider connecting a dummy load.

You can get more detailed answers by using TI's calculation tools and forms.