Serial Termination Resistor Specification

[rolf_voler]

What are the tolerance specifications for the D+/D- Serial Termination resistors?  We are restricted to use a 100ohm cable, and may be experiencing reflections due to the cable termination mismatches.  What are the specifications for the upstream series termination resistors built into the device?

[Sananya_14 · Accepted solution]

Hello,

The D+/D- series termination resistors are integrated in our USB 2.0 hubs such as HX2VL and HX2LP. The  resistance on the D+/D- lines of HX2VL is 45 ohms which is the standard value for matching the 90 ohms differential impedance of the traces. Please refer to the App Note for detailed layout guidelines for the traces.

Best Regards,
Sananya

[rolf_voler]

What are the tolerance specifications?

[Sananya_14]

Hello,

As per the USB 2.0 specification, the differential impedance of the D+/D- lines should be 90 ohms+/- 10 percent.

Best Regards,

Sananya