Datasheet Summary
Upstream USB Port Terminator
Product Description The PACUSB- U1, PACUSB- U2, and PACUSB- U3 are single- channel USB upstream- port termination networks. The PACUSB- U1/U2/U3 integrate EMI/RFI filter ponents R1 and C1, as remended by the USB specification. Because these are upstream USB devices, they are terminated with a single 1.5 kW pull- up resistor to V3.3 (R2).
There are three options for the value of the series resistor R1:
- For PACUSB- U1, R1 = 15 W
- For PACUSB- U2, R1 = 33 W
- For PACUSB- U3, R1 = 22 W
This series resistance plus the USB driver output resistance must be close to the USB cable’s characteristic impedance of 45 W (90 W balanced) to minimize transmission line...
