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TPS92515HV: PWM dimming problem

Part Number: TPS92515HV

I did reference using TPS92515HVEVM-749 schematic.

It worked dim with fix IADJ and PWM 16KHz.

Because of flicker, I had to change the fsw frequency(580KHz -> 700KHz). 

and It was working mistic. 

When I was PWM Dim up, LED was more illuminated and stay normally.

I did change the PWM frequency 1KHz to 16KHz.

But 1~10KHz PWM frequency had made an Inductor's ringing noise.

I did Dim up, more illuminated's problem is made currently. 

I want to know about that.

Below is my schematic

Vin was average 52V. Vled is below 46V. Iled is Max 0.8A.

  • Hello,

    I'm not sure what you are stating above. "It was working mistic", I don't understand what this means. If you are using PWM on the IC at 16 KHz it will take 6.3 uS to charge the inductor to 0.8A. It will discharge from 0.8A in 0.82 uS. This can make the dimming look non-linear.

    I also don't understand "I did Dim up, more illuminated's problem is made currently." What problem is there?

    All I understand is the PWM frequency is 16 KHz, the Fsw is 700 KHz but I don't know what your dimming issues are.

    Regards,
  • I have not heard back from you so I believe you may have solved the issue.
    The thread will close now but will reopen if you reply.