LM5175: Did LM5157 is suit to do LED driver?

Jacking Jin

Part Number: LM5175

Dears,

LM5175 is a good wide input and output Buck-Boost converter, I want used it to design LED driver, because I found the HDRV2 pin product the PWM signal after the output voltage need to establied. If my load is LED that the output voltage can't first existence, so the HDRV2 pin is still no PWM signal and the mosfet will become so hot. Do you have a good method to solve it? Many thanks!

Best regards!

Jacking

over 8 years ago

0 Vijay86929 over 8 years ago

TI__Genius 11490 points

Hi Jacking,

Please refer to the reference design PMP10592 on the TI website that has a sample LED dimming design.

Regards

0 Jacking Jin over 8 years ago in reply to Vijay86929

Expert 1145 points

Dear Vijay,

Thanks you for your reply!

The reference design is similar with the LM5175's DEMO, I have test the DEMO and change the Rsns to 0.015Ω, if I starting under load that the HDRV2 can't product the PWM signal in the BOOST mode. It's ok on during the no-load start. Could you help me give some suggestions? Many thanks!

Best regards!

Jacking

0 Vijay86929 over 8 years ago in reply to Jacking Jin

TI__Genius 11490 points

Hi Jacking,

The reference design has an switch that open the load before startup. That prevents the HDRV2 latchoff.

regards

0 Jacking Jin over 8 years ago in reply to Vijay86929

Expert 1145 points

Dear Vijay,

I'm a bit confused, as you talk, if i used the LM5175 to driver the LED that I needed no-load before startup, and then with load. If like this I will can't directly to driver the LED.

Best regards!

Jacking

0 Jacking Jin over 8 years ago in reply to Jacking Jin

Expert 1145 points

Dear Vijay,
Could you kindly give me suggestion? Thanks very much.
Best regards!
Jacking

0 Vijay86929 over 8 years ago in reply to Jacking Jin

TI__Genius 11490 points

Hi Jacking,

I think PMP10592 utilizes a PWM switch in addition to the LM5175 converter. Are you trying to do analog dimming or PWM dimming?

0 Jacking Jin over 8 years ago in reply to Vijay86929

Expert 1145 points

Dear Vijay,

I will to do PWM dimming, and I had test the DEMO of LM5175, It's Certainly appear the phenomenon as mentioned above. Thanks!

Best regards!

Jacking

0 Jacking Jin over 8 years ago in reply to Jacking Jin

Expert 1145 points

Dear Vijay,

Could you give me some suggestion for the case? Many thanks!

Best Regards!

Jacking

Power management

Power management forum

LM5175: Did LM5157 is suit to do LED driver?