TLC59282 noise burst

Bob Gardner

Have a keypad with dome switches and leds. I see a burst of noise on the led outs. I'm using the blank to pwm all 16 channels, 2 packs daisy chained. I think this noise burst is coupling to my inputs. The noise burst gets wider and skinnier with pwm. Anyone see this? Can it be eliminated? Workaround?

over 8 years ago

0 Feifei Shen over 8 years ago

TI__Expert 3275 points

The noise is related with your input SCLK or not?
Or it just surge current when Chs is on.Best regards,Feifei

0 ROBERT GARDNER over 8 years ago in reply to Feifei Shen

Prodigy 10 points

SCLK is 8MHz. I use pwm on the blanking line to dim them all. When blanking line is low, there is an rf burst on the led out that extends a volt or more above and below 5V. Anyone ever seen this phenomenon? How to damp it/eliminate it? I think this is coupling over to my switch matrix and causing spurious keypresses.

0 Feifei Shen over 8 years ago in reply to ROBERT GARDNER

TI__Expert 3275 points

In that way, you can add small cap on the out to decrease the slew rate when chs open.

Best regards,
Feifei

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TLC59282 noise burst