TPS922050: LED Driver Recommandation

Hi

Our expert is out of office due to Chinese New Year, he will reply you on 2.5

Hi Jeremy,

I am currently out of office for Chinese New Year Holiday. I will reply to you on Feb.8 when I am back to office. Thanks for your understanding.

Best Regards,

Steven

Hi Jeremy,

I am back to office earlier than expected :)

For ≥90W power output, TPS922052/3 is a possible solution. TPS922050/1 cannot output such high power.

What is the upper limit of the power output you expect?

Best Regards,

Steven

Hi Steven,

Given the 90W limit per port for PoE, what do you think is our best option for the LED driver?

Would combining multiple ports to achieve higher power be a viable approach?

Looking forward to your thoughts.

Jeremy

Hi Jeremy,

If the max power output is 90W, then I would recommend TPS922052/3 here.

Also, you can combine multiple TPS922050/1 to achieve such high power output.

Best Regards,

Steven

Hello,

what would you recommend we follow for design guidelines except the datasheets?

Best regards,

Jeremy

Hi Jeremy,

If you would like to choose TPS922052/3, then I would recommend you go through the FAQs listed in this E2E thread - [FAQ] List of FAQs for TPS922055 / TPS922054 / TPS922053 / TPS922052 LED driver - Power management forum - Power management - TI E2E support forums.

Best Regards,

Steven

Hi Steven,

I had a question about how the TPS922054 works. From what I understand, it is current based. I was wondering, if my Rsense is 0.05ohm, will the TPS922054 try to push 4A on its ON time or does the current vary depending on the PWM input.

We're having issue when we connect our led bar to our system the led bar flashes once at full intensity and then becomes very dim whatever the PWM input is. My voltage drops from 55V to 34V. The led bar is rated for 48V-60V at 40W.

Here's my schematic. Let me know if you think of anything that could cause this issue.

Best regards,

Jeremy

Dear Jeremy,

If the Rsense is 0.05ohm, the LED current is set as 4A. And if you choose PMW dimming, when the PWM input signal at the PWM pin turns from low to high, the internal NMOS FET starts switching and the inductor current rises to the determined value. The LED current is then regulated at the determined value as long as the PWM input signal stays high. When the PWM input signal turns from high to low, the internal FET is turned off causing the inductor current falling to zero. The internal FET maintains off and the LED current stays zero as long as the PWM input signal stays low.

Jeremy Dufresne said:

I had a question about how the TPS922054 works. From what I understand, it is current based. I was wondering, if my Rsense is 0.05ohm, will the TPS922054 try to push 4A on its ON time or does the current vary depending on the PWM input.

Could you pls kindly clarify the test condition when this issue happen? I am not sure if there is a case happen that VIN is 34V and LED string voltage is 48V ~ 60V (12pcs ~ 20pcs LEDs)?  

Jeremy Dufresne said:

We're having issue when we connect our led bar to our system the led bar flashes once at full intensity and then becomes very dim whatever the PWM input is. My voltage drops from 55V to 34V. The led bar is rated for 48V-60V at 40W.

Thank you!

BRs

Lucia

When I connect the led bar to the output of the TPS922054, the voltage goes from 55V to 34V. it's a 4ft led bar with around 260 leds in series and/or parallel. they have a 2.5V forward voltage and around 40W of power altogether so around 750mA.

Hi Lucia,

I changed the 10K I had for a 100K on UVP and it solved my issue. Our VIN is between 48 and 60V, usually around 55V. If you have a value recommandation for R_UVP1 and R_UVP2 we're always open to making our design better! Same thing if you look at my schematic and see some values you'd change.

Thanks for your help!
Best regards,

Jeremy