Usb peripheral rc termination

Hi All,

I have read that USB hubs require termination R's and C's on the Upstream and Downstream ports. Though, I have not read and cannot find any information for termination on the actual peripheral. For example if I were designing a mouse to use on my computer would it be wise to add the termination R's and C's to mouse PCB?

The resistor is a 22 ohm series resistor and the cap is a 22pF from the signal to GND.

Thanks!

Have a look on MicroChip, they have an application note for creating a USB mouse using a PIC - check the circuit they use.

Great idea.

I found this: https://ww1.microchip.com/downloads/en/DeviceDoc/51526b.pdf

I scrolled down to page 38 and they have the USB data signals going strait from the Micro over to the Connector J1. From what I see it goes through a zero ohm resistor and that's it. So, it appears that on the peripheral side of the USB connection there are no termination R's and C's.

I guess I could tear open my USB mouse kicking around...let me try that.

Thanks

After opening up a COTS Logitech optical USB mouse I verified that they do not use termination R's and C's as well.

Does anyone have an good explanation for the use of term termination in the USB world? Why is it important to have series 22 ohm resistors on the data lines and a 22pF cap to GND. I have seen data sheets for USB parts that use these. Exactly why?

The USB on a mouse is HID standard [human interface device] which is the slowest USB I know, it compares with a 9600Baud RS232 link for speed.
It would not require the RC termination network.

I never fit them on a HID device.

The USB2 and higher would require correct termination R/C.

ericgibbs said:

The USB on a mouse is HID standard [human interface device] which is the slowest USB I know, it compares with a 9600Baud RS232 link for speed.
It would not require the RC termination network.

I never fit them on a HID device.

The USB2 and higher would require correct termination R/C.

Click to expand...

Thanks!