GD75232: GD75232 output signal issue when power ON

user3830479

Part Number: GD75232
Other Parts Discussed in Thread: GD65232

Dear all:

My customer use GD75232 of their RS232 port ,they feedback an issue. attached is circuit.

Power sequency follow VDD-VSS-VCC-VIO(-12V to 12V to 5V）, when +12 power on, Output PIN have a pulse up to 3V, and then down to

-12V(normal voltage) before signal input. we have a doubt that is it normal for this IC? How can we eliminate the pulse? please help to check,

over 7 years ago

0 Hao L over 7 years ago

TI__Mastermind 25705 points

Thanks for using our device. The power sequence of GD75232 should be: (quote from datasheet)

When powering up the GD65232 and GD75232, the following sequence should be used:

1. VSS

2. VDD

3. VCC

4. I/Os

What's the state of input after power on, is it biased for floating? You can refer to the waveform of this post (e2e.ti.com/.../2248651) for previous discussion about the device. Please let me know if you have any questions, please let me know.

Regards,

Hao

0 user3830479 over 7 years ago in reply to Hao L

Expert 1090 points

Yes , I following the sequence, when VDD +12 supply, Output PIN have a pulse up to 3V(not signal input), it is generated by GD75232? is it normal for this IC?

0 Hao L over 7 years ago in reply to user3830479

TI__Mastermind 25705 points

Can you please upload the waveform? Or if you can confirm they look like this one, they may be normal. Thanks!

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GD75232: GD75232 output signal issue when power ON