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 components R1 and C1 as recommended by the USB specification. Because these are upstream USB devices they are terminated with a single 1.5kW pullup resistor to V3.3 (R2). There are three options for the value of the series resistor R1: For PACUSB-U1 R1=15O For PACUSB-U2 R1=33O For PACUSB-U3 R1=22O. This series resistance plus the USB driver output resistance must be close to the USB cables characteristic impedance of 45O (90O balanced) to minimize transmission line reflections. In addition these parts provide a very high level of protection for sensitive electronic components that may be subjected to electrostatic discharge (ESD). The input and output pins are designed and characterized to dissipate ESD strikes of 15kV safely a level well beyond the maximum requirements of the IEC 61000-4-2 international standard. Using the MIL-STD-883D (Method 3015) specification for Human Body Model (HBM) ESD all pins are protected for contact discharges to greater than 30kV. The PACUSB-U1/U2/U3 is housed in either a 6-pin C70 or 6-pin SOT23 package and is available with optional lead-free finishing.