P82B96: Power supply

Hi Yumiko-san,

"Why do you use separate power supply from the P82B96 and other circuits?"

Do you mean the 12V on the P82B96 and 3.3V-5V on the I2C bus? If you use 12V on the Vcc of the P82B96, then you have a larger noise margin on the cable end (Tx/Rx and Ty/Ry)

"are there any special considerations or design requirements?"

I would suggest using clamping diodes on the cable connection sides to ensure the parasitic inductance on the cable doesn't introduce large negative swings on the device pin when drivng low.

"Is there any effect on using separate power supply?"
Do you mean two different 12V lines? It shouldn't make a difference as long as the GND connections are the same and there aren't huge GND shifts between the two boards.

-Bobby

"Hi Bobby,

thank you for your response.

is there any problem that on using the same power source 3.3 V on both sides of P82B96 if there is no problem with the SN ratio.

Thanks.

Regards,"

^^I saw this through the email notification, I'm not sure if the post was deleted from this thread by our system by accident but I'll respond just incase.

Our Sx/Sy side of the device doesn't use a ViL of 30% or 70% so having a 3.3V logic on I2C itnerface side (Sx/Sy) is fine, as long as you can accept the large VoL the device generates and also can drive below the ViL the device requires.

Thanks,

-Bobby