TPS92641: different rise time which causes gray scale discontinuous

Ann_Lien

Part Number: TPS92641

Hi expert,

My customer has a question on TPS92641 rise time shown below. We can see there is different rise time when PWM is high. Different rise time causes gray scale discontinuous and it seems like there is not consist with previous status. For example, previous status for (2) and (3) are all high but (2)'s rise time would be shorter than (3)'s. Would you kindly help to see if there is any clue for it? Or is it normal operation for this part? Thanks a lot!!

Best regards,

Ann Lien

over 6 years ago

0 Irwin Nederbragt over 6 years ago

TI__Mastermind 28655 points

Hello Ann,

I would guess that the current level is different when the strobe is activated or, if this is shunt-FET dimmed, the drive is changing. Can you look at the LED current, input voltage, as well as other signals such as lower gate drive, shunt-FET drive, etc. Are there capacitors across the LEDs and are they different values depending on the color?

Best Regards,

0 Irwin Nederbragt over 6 years ago in reply to Irwin Nederbragt

TI__Mastermind 28655 points

Hello Ann,

I haven’t heard back from you, I’m assuming you were able to resolve your issue.
If not, just post a reply below (or create a new thread if the thread has locked due to time-out)

Best Regards,