LM3406: LM3406 PWM Dim

Bo Zeng Peng

Part Number: LM3406

We have a custom designed led driver using LM3406. The schematic is following the schematic of design example 1 in the datasheet. We use arduino to generate PWM to control the dim pin. But we get strange results. According to datasheet when dim pin gets low level, the leds should be off. And leds is on when dim pin gets high.

Actually we get completely opposite result. We want to know if anyone in the forum has same issue so that can provide us some hints.

Best Regards,

over 7 years ago

0 Clinton Jensen over 7 years ago

TI__Mastermind 25500 points

Hello Bo,

That is odd and I have not seen that before. I have used the EVM quite a few times as well. Are you probing the DIM pin directly? Can you send a scope shot with the DIM waveform versus LED current (or the SW pin voltage if that is easier)?

Thanks,

Clint

0 Bo Zeng Peng over 7 years ago in reply to Clinton Jensen

Prodigy 130 points

Hello,

We test more cards. And other cards work normally. So probably something happens during assembling.

Thanks for reply.

Power management

Power management forum

LM3406: LM3406 PWM Dim