TRS3232 outpu of startup

PAN-M

Other Parts Discussed in Thread: TRS3232, TRS3232E

Dear all.

Do you have startup state of output of TRS3232?
Our customer have a problem.
Receiver Board startup first
Turn on TRS3232
DOUT of TRS3232 is High (Several microseconds)
When TRS3232 is power up, DOUT is Low

Regards,
PAN-M

over 10 years ago

0 Ron Michallick over 10 years ago

TI__Guru**** 171776 points

PAN-M

During power up of the system, the DIN inputs might not be driven high by the device that drives them.
Be sure DIN = VCC during power up phase to help keep DOUT from going high.

0 PAN-M over 10 years ago in reply to Ron Michallick

Mastermind 8375 points

Ron

A schematic and waveform from our customer are attached.

TRS3232_startup.pdf

Regards,
PAN-M

0 Ron Michallick over 10 years ago in reply to PAN-M

TI__Guru**** 171776 points

PAN M,

I see the the input is low when output is high. This is correct device behavior.
The 5V supply wasn't shown, but I believe the 5V powers up before 3.3V supply.

If the U0RX and U0TX are 3.3V logic, why does TRS3232E run from a 5V supply?

0 PAN-M over 10 years ago in reply to Ron Michallick

Mastermind 8375 points

Ron

I received waveform which include power line from our customer.

U0TX is late after VCC5PO(VCC of TRS3232) stands up.
U0TX is pulled up from VCC3P3.
I send to our customer this is why TXD will be High.

Thanks
PAN-M

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TRS3232 outpu of startup