UCD3138A: Why some I/O pin will rise up a little bit(less than 1V) during V33D rising up?

Dana Huang

Part Number: UCD3138A

Hello

Why some I/O pin will rise up a little bit(less than 1V) during V33D rising up? Here is the waveform I got. Channel 1(Yellow) is SCI_RX0 pin, Channel 2(Green) is V33D.

over 6 years ago

0 Yitzhak Bolurian over 6 years ago

TI__Mastermind 18370 points

IS SCI_RX0 connected to any external component at the time of ramp up?
Can you plot the UCD's GND pin at the same screen shot?

0 Dana Huang over 6 years ago in reply to Yitzhak Bolurian

Prodigy 230 points

Yes, it was connected to the cathode of an photocoupler. I disconnected it and it stayed at 0V during at the time of V33D ramp up.
Thanks for your help(^o^)／

Best Regards
Dana Huang

Power management

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UCD3138A: Why some I/O pin will rise up a little bit(less than 1V) during V33D rising up?