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LTC3783 - High ripple in pulse skip mode

Thread Summary

The user is experiencing increased output ripple in an LTC3783-based circuit when operating in pulse skip mode with lighter current adjustments or loads. The final solution suggests increasing the output capacitors to reduce the ripple. The user is also considering changing the transformer ratio or reducing the switching frequency for light loads.
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Hello,

I'm testing a circuit with LTC3783. It is an adjustable 4 mA to 200 mA pulsed current source with variable load. The power supply is stable while the controller is operating without pulse skipping. Se the following figures.

First image is a capture of the output (yellow) and the compensator voltage. Other two figure are the ouput (yellow) and the GATE voltage.

But with lighter current adjustment and/or load, the output ripple rises (see figures below). Output voltage is the yellow line. In first image the green line is the compensator voltage and the GATE signal in the other ones.

Could you indicate any reference to help me on adjusting the compensator or other aspect in order to reduce this ripple (in pulse skip mode)?

Besides trying to adjust the compensator, other options I'm testing is to change the transformer ratio or reduce the switching frequency for light loads/adjustments.

Best Regards,

Luiz H. Y. Mellucci.

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