Hi E2E,
When using SN65HVD1781QDRQ1 for design testing, the communication waveform fluctuates.
Is there any suggestion for improvement?
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Hi E2E,
When using SN65HVD1781QDRQ1 for design testing, the communication waveform fluctuates.
Is there any suggestion for improvement?
This is only common-mode noise; the differential voltage looks OK.
Ensure that the decoupling capacitor C1501 is as near the transceiver's VCC pin as possible. But that ringing has a very low frequency (I'd estimate about 500 kHz); check if it also occurs in the VCC and GND lines (measure pin 5 against GND at the power supply).
Hi Clemens,
Thanks for your advice.
This situation was improved by removing the common-mode inductors.
However, There is always a short period of low level in the beginning, I do not know what factors will cause it?
Hi Tommy,
Do you have a scope shot of the Enable signal and the DI signal during the change - I suspect that Clemens could be correct on the DI pin voltage not being correct - but I am not 100% sure as it seem per schematic that the DI pin should be held high in case of Idle.
Best,
Parker Dodson