LM3409: PWM frequency range

Jerry Hu

Intellectual 1450 points

Part Number: LM3409

Tool/software:

Hi team

I would like to help my customer JUNJIE for the question:

What is the PWM frequency range of LM3409, we don't fine the exact range of this, not 10000:1.

Thanks~

4 months ago

0 Hailee Xu 4 months ago

TI__Genius 10120 points

Hi Jerry,

Please refer to blew post, it can help you understand the meaning of 10000:1.

(+) LM3409-Q1: How to understand 10,000:1 PWM Dimming Range - Power management - INTERNAL forum - Power management - INTERNAL - TI E2E support forums

Additionally, what is your expected PWM frequency? usually when you use different dimming method, it would be different, shunt dimming could support a higher PWM frequency which is shown in the Figure 15 and Figure 16 of the datasheet. Thanks!

0 Jerry Hu 4 months ago in reply to Hailee Xu

TI__Intellectual 1450 points

Hi Hailee

I see, but they said 25Hz or 30Hz, is it OK?

0 Daniel Louis 3 months ago in reply to Jerry Hu

TI__Expert 5720 points

Hi Jerry,

25Hz or 30Hz is fine as long as your on time is long enough to support charging your off-time network.

Best,
Daniel

Power management

Power management forum

LM3409: PWM frequency range