STF203-22

The STF203-22 is a combination EMI filter and line termination device with integrated TVS diodes for use on upstream USB ports. It is constructed using a proprietary technology that allows passive components and TVS diodes to be integrated in the same package. Each device will provide termination, filtering, and ESD protection for one upstream USB port.

The STF203- 22 is an easily implemented solution for meeting the requirements of revision 1.1 of the Universal Serial Bus specification. USB line termination is achieved with 22Ω series resistors on both the D+ and D- USB lines. These resistors preserve signal integrity by matching the cable impedance to that of the differential driver. The 1.5kΩ pull-up resistor completes the termination circuit on each line. This resistor is required by the USB specification to identify the equipment as either a full-speed (connected to D+ line) or low-speed (connected to Dline) device.

The 47pF capacitors are used to bypass high frequency energy to ground and for edge rate control of the USB signals. Finally, the STF203-22 contains TVS diodes for ESD protection of both (D+ & D-) data lines and the voltage bus (VBUS). The TVS diodes provide effective suppression of ESD voltages in excess of 15kV (air discharge) and 8kV (contact discharge) per IEC 61000-4-2, level 4. The small size and integrated feature of the STF203- 22 minimizes required board space. The STF203-22 is suitable for use in USB hubs, computers, peripherals, and portable devices.