MAX3232: MAX3232 output waveform abnormal

jeno.zhang

Part Number: MAX3232

Hi，

MAX3232 output waveform is abnormal (waveform distortion), as shown in the following figure. Please help analyze the cause.

Thanks！

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 316690 points

RS-232 uses both positive and negative voltages. A unidirectional diode like the PESD15VS2UT tries to clamp negative voltages to GND.

0 Parker Dodson over 2 years ago

TI__Guru 52102 points

Hi Jeno,

Clemens is correct - you have unidirectional diodes that seem to want to bring the rail to ~0V when driver outputs a negative value (which is expected). You need bi-directional protection devices so that both positive and negative signals can be transmitted over the line.

Best,

Parker Dodson

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MAX3232: MAX3232 output waveform abnormal