TLC5947: SPI to 24PWM

GARETH OU

Part Number: TLC5947

Customers using TI TLC5947 are SPI to 24PWM output, but his output will have abnormal waveforms as follows. Any comments? Thank you

1. 50% duty @30Hz frame rate, the abnormal PWM output as in red mark and we can observe the LED flicker

50% duty @120Hz frame rate, the abnormal PWM output as in red mark but we can not observe the LED flicker

over 2 years ago

0 Aaron Bing over 2 years ago

TI__Expert 4160 points

Hi Gareth,

It is acceptable that the LED flicker cannot be observed by human eyes as frame rate goes higher than 120Hz. There are many potential causes of LED flicker issues. Do you mind to provide more information on the circuit schematic and SPI interface?

Best Regards,

Aaron Bing

0 GARETH OU over 2 years ago in reply to Aaron Bing

Mastermind 9495 points

Hi Aaron

We think the abnormal waveform is from the different frames change. EX: 30HZ to 50HZ.

Do you have any suggestion for the TI chip output different frames? EX Add delay or something? Thank you.

0 GARETH OU over 2 years ago in reply to GARETH OU

Mastermind 9495 points

Hi Aaron

Do you have any suggestion

0 Aaron Bing over 2 years ago in reply to GARETH OU

TI__Expert 4160 points

Hi Gareth,

Could you capture the waveforms of BLANK, XLAT, SIN, and SOUT? I think the glitch is the result of improper data writing. For instance, if you toggle the latch signal XLAT when BLANK is low, it interferes with the CLK cycle counting from 0~4095.

Best Regards,

Aaron Bing

Power management

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TLC5947: SPI to 24PWM