SN65HVD72: output abnormal sometimes

Betty Guo

Part Number: SN65HVD72

Hi team,

customer test SN65HVD72DR,found sometimes the output is worng.check the output waveform as below:

input as below:

wrong output A:

normal output A:

as wrong output A show, the receiver will receive more than 1 bit data, which cause the data error.

could you help give comments about why the output have a low level at the end of data straming? thanks

0 Clemens Ladisch over 4 years ago

Guru 300760 points

This could be explained by the DE input going low at that point. Can you show a capture of both DE and A?

0 Betty Guo over 4 years ago in reply to Clemens Ladisch

Hi Clemens,

attached customer schmatic and DE&A waveform:

0 Clemens Ladisch over 4 years ago in reply to Betty Guo

Guru 300760 points

As far as I can see, the DE input indeed goes low after A has gone low.

How is VP_RS485_DE controlled? Why does VP_RS485_TXD go low after the packet?

0 Eric Hackett over 4 years ago in reply to Clemens Ladisch

Clemens,

Thanks for the help here as always.

Betty,

Any updates on this?

Regards,

Interface forum