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LM3402 Ripple

Andre Andreta
Prodigy 10 points
Other Parts Discussed in Thread: LM3402

I made a LED driver with LM3402, to source 500mA to 2 HB LEDs (6,8V), with a 24V input.

It's working properly with an 47uH Inductor, and a Output Capacitor of 220nF. Providing about 5% ripple current.

In order to achieve a larger output current ripple, I tested lower Inductors and lower capacitors (and even removing the output capacitor).

But with any capacitance and indutance lower them the first used, the LM3402 doesn't works properly. Its ton, that must be greater them 300ns, reaches about 150ns, and dont matter witch Ron(Resistor that controls on time) I use, it makes no effect. The LEDs still lighting up, but my output current reaches frequencies up to 1.7MHz.

Any ideas how to get a larger output current ripple?