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LM3414HV: LEDs are flashing at lower end when dimming down

Part Number: LM3414HV

Hi all,

I'm working on a Board where we have 16 circuits with LM3414HV. Each circuit

is dirivng 3 LEDs the Input Voltage is 12V.

L1 is 100µH

ILED is 0.5A

D1 is 2A Vf 0.56V

I have tried 450 kHz for fsw what was aweful, afterwards I've tried to use a single frequency for every chanel between 330 - 450 kHz what makes

it better.

For Cin I've used 10µF in the begining and also tried now after frequency changing above to use a 4.7µF and a 2.2µF capacitor.

The used PWM for dimming is 2kHz fix.

My problem is that I have a randomized flash on a single circuit when dimming down at a low end of about 4 to 5 % PWM its really randomizing

and most times its just one channel at one time.

Any ideas how to get rid of this issue?

Thanks in advance.