USB Upstream Port Filter and TVS
For EMI Filtering and ESD Protection
PROTECTION PRODUCTS
Description
The STF202 is a combination EMI filter and line termi-
nation device with integrated TVS diodes for use on
upstream USB ports. It is constructed using a propri-
etary 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 STF202 is
an easily implemented solution for meeting the require-
ments 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 1.5kΩ
pull-up resistor completes the termination circuit on
each line. This resistor is required by the USB specifi-
cation to identify the equipment as either a full-speed
(connected to D+ line) or low-speed (connected to D-
line) device. The 47pF capacitors are used to bypass
high frequency energy to ground and for edge rate
control of the USB signals. Finally, the STF202 con-
tains TVS diodes for ESD protection of both
(D+ and D-) data lines and the voltage bus (V
BUS
). 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 STF202
minimizes required board space and increases system
reliability. The STF202 is suitable for use in USB hubs,
computers, peripherals, and portable devices.
STF202-22 and STF202-30
Features
Bidirectional EMI/RFI filtering and line termination
with integrated ESD protection
ESD protection for USB power (V
BUS
) and data lines
(D+ and D-) to
IEC 61000-4-2 (ESD) ±15kV (air), ±8kV (contact)
IEC 61000-4-4 (EFT) 40A (5/50ns)
Filtering and termination for two USB data lines
Different series resistors for impedance matching
Low TVS operating voltage (5.25V)
Low leakage current
Low capacitance
Solid-state technology
Mechanical Characteristics
EIAJ SOT23 6L package
Molding compound flammability rating: UL 94V-0
Marking : Marking Code
Packaging : Tape and Reel per EIA 481
Applications
USB Hubs
Portable electronics
Cellular Handsets
Modems
Peripherals
Servers, Desktop, Notebook, and Handheld
Computers
Circuit Diagram
Schematic and PIN Configuration
.
S0T23-6L (Top View)
Revision 08/11/04
1
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