TPS92513 1000:1 dimming, 1250kHz PWM

Jenny Collier

Other Parts Discussed in Thread: TPS92513HV

Hi, We are using a design based on the TPS92513HV with Vin = 48 Volts, LED string around 32 Volts and LED current around 270mA. We would like to dim to very low dim levels, namely 1/1000 at 1250kHz PWM.

Initially we were having issues and it appeared that the compensation capacitor was not charging fully. I changed the compensation capacitor from 0.1uF to 0.01uF and now we can dim as low as 5/1000 reliably. However, we would like to go down as low as 2/1000 and I was wondering if I should reduce the compensation capacitor value further, and what is the minimum value that you would recommend? Do you have any other suggestions?

We are not concerned about linearity, only flicker

Thanks,

Jenny Collier

over 7 years ago

0 Clinton Jensen over 7 years ago

TI__Mastermind 25500 points

You could probably go as low as 1nF on the COMP capacitor. If you do and the part does not oscillate you should be ok. If you really need to increase bandwidth further you will likely need to go to an RC from COMP to ground. Hopefully you do not need to, but if so you can refer to the loop compensation in the attached document. These devices share the same control loop.

slua628a.pdf

0 Jenny Collier over 7 years ago in reply to Clinton Jensen

Prodigy 20 points

Thanks so much Clinton, I'll have a look at the document.

Regards,

Jenny

Power management

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TPS92513 1000:1 dimming, 1250kHz PWM