STF201

The STF201 is a combination EMI filter and line termination device with integrated TVS diodes for use on downstream 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 downstream USB port.

The STF201 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 series 22Ω or 30Ω 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 15kΩ pull-down resistors complete the termination circuit on each line. They are required by the USB specification to identify the line as a downstream connection.

The 47pF capacitors are used to bypass high frequency energy to ground and for edge rate control of the USB signals. Finally, the STF201 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 STF201 minimizes required board space and increases system reliability. The pin-out of the device allows easy implementation. The STF201 is suitable for use in USB hubs, computers, peripherals, and portable devices.