TRS3232E-Q1: When unpowered, does the receiver input impedance change and would it damage an active remote device?

Jonathan_

Part Number: TRS3232E-Q1
Other Parts Discussed in Thread: TRS3232E,

The receiver input impedance ri is given in the datasheet for when the device is powered. However if the device is unpowered, does the input impedance change?

PS: the datasheet for device TRS3232E (without the -Q1 suffix) states that it will not damage a remote device when unpowered in section 8.4.2.

over 3 years ago

0 Eric Hackett over 3 years ago

TI__Guru 66382 points

Jonathan,

You can expect the same behavior between the TRS3232E and TRS3232E-Q1. Like most of our transceiver devices, when unpowered the pins become high-impedance, so no damage should be expected. I've notified our RS232 expert of this thread to comment further if necessary.

Regards,

Eric Hackett

0 Hao L over 3 years ago in reply to Eric Hackett

TI__Mastermind 25705 points

Jonathan,

The internal 5kOhm pulldown resistance is with respect to ground and is passive, whose value doesn't change with the supply.

0 Jonathan_ over 3 years ago

Prodigy 20 points

Thank you for your replies. So when the TRS3232E-Q1 is unpowered, the only impedance visible to the remote device is the internal 5k resistance? Or is there ESD protection that remains visible?

+1 Hao L over 3 years ago in reply to Jonathan_

TI__Mastermind 25705 points

Yes, the unpowered RIN impedance is still 5kOhm. The ESD protection remains inactive unless the input voltage satisfies its triggering condition that is not within the normal operation region.

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TRS3232E-Q1: When unpowered, does the receiver input impedance change and would it damage an active remote device?