SN65175: SN6517

Erfan Omidvar

Prodigy 80 points

Part Number: SN65175

Tool/software:

Hello,

I am using SN65 for my RS-485 data line.

Im not sure if my configuration is correct since some times it has some ringing on my 5V. and also on my relay

Any help?

7 months ago

0 Michael Ikwuyum 7 months ago

TI__Guru 50906 points

Hi Erfan,

Today is a US holiday. Please help give some time for expert feedback, thanks.

Best Regards,

Michael.

0 Clemens Ladisch 7 months ago

Guru 316780 points

The schematic does not show a relay.

Does the ringing happen at the same time as the signals switching on DI/A/B?

0 Erfan Omidvar 7 months ago in reply to Clemens Ladisch

Prodigy 80 points

Relay is at the other end(Below)

And answer to your question, no, rining happen when it its in steady state. without any input.

and rining on 5v, led to Disfuncttion of my Q6, driver for the relay

+1 Clemens Ladisch 7 months ago in reply to Erfan Omidvar

Guru 316780 points

Then it is probably not related to the SN75176. (That schematic looks OK.)

I'd guess that some other device connected to the 5 V supply generates noise, or that noise is induced into the 5 V line from some other line running in parallel.

+1 BOBBY 7 months ago in reply to Erfan Omidvar

TI__Guru 72981 points

Hi Erfan,

Just to be sure... The SN65176 isn't connected to the relay right? It looks like your schematic cuts off after the 120 ohm resistor. If so, I believe Clemens is correct in that the two probably aren't related.

Is the ringing causing any kind of signal integrity issues on the RS485 transceiver?

If the ringing isn't too bad, you may be able to smooth it out by adding more capacitors in parallel on the 5V rail.

-Bobby

0 Erfan Omidvar 7 months ago in reply to Clemens Ladisch

Prodigy 80 points

that 100NF is not low? Now Im checking agin the datasheet, and it looks like it suggested 1.5uF

0 Ethan Sempsrott 7 months ago in reply to Erfan Omidvar

TI__Genius 13642 points

Hi Erfan,

100nF is not too low. If the ringing is not too significant, you can add a 1uF or 1.5uF capacitor to the VCC line in parallel to the 100nF cap.

Best,

Ethan

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SN65175: SN6517