MAX3243E: How to communicate between two auto-powerdown RS232 transceiver

Antonio Chen

Part Number: MAX3243E

Hello Sir,

As datasheet mention in auto-powerdown mode, the driver will disable if no valid signal at at RX_IN.

So we can't to do loop-back test (TX_OUT connect to RX_IN) when hardware configure as auto-powerdown mode (FORCEON= LOW, FORCEOFF=HIGH) right?
Two device can't communicate if both hardware configure as auto-powerdown mode (FORCEON= LOW, FORCEOFF=HIGH) right?

Is that mean, auto-powerdown mode transceiver only can communicate with without auto-powerdown transceiver otherwise will not workable?

Looking forward your comment. Thanks!!

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 318050 points

Auto-powerdown happens after 30 µs. So you will get this problem only if the two devices are switched on (and power down) before they are connected to each other.

0 Antonio Chen over 4 years ago in reply to Clemens Ladisch

Prodigy 40 points

Hello Sir,

I'm not fully understand your answer. Could you please answer my question more clear? Thanks!!

0 Clemens Ladisch over 4 years ago in reply to Antonio Chen

Guru 318050 points

Sorry, I overlooked that you are doing loopback.

With loopback, this problem cannot happen. TX_OUT will output a valid signal for at least 30 µs, which will keep the transceiver out of powerdown mode.

0 Antonio Chen over 4 years ago in reply to Clemens Ladisch

Prodigy 40 points

Hello Sir,

How about two auto-powerdown mode transceiver communication? Once transceiver configure to auto-powerdown mode, the driver (TX) need enable by valid signal at RX_IN. So both side RX_IN are waiting for other side transmit valid signal, but both side TX always disable. Is that mean two auto-powerdown mode transceiver communication can't workable? Could you please give some comment for it? Thanks!!

0 Clemens Ladisch over 4 years ago in reply to Antonio Chen

Guru 318050 points

See my first answer.

0 Antonio Chen over 4 years ago in reply to Clemens Ladisch

Prodigy 40 points

Thanks!!

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MAX3243E: How to communicate between two auto-powerdown RS232 transceiver