1www.semtech.com
PROTECTION PRODUCTS
STF202-22 and STF202-30
USB Upstream Port Filter and TVS
For EMI Filtering and ESD Protection
Description Features
Schematic and PIN Configuration
Revision 08/11/04
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 22 or
30 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 1.5k
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 (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 STF202
minimizes required board space and increases system
reliability. The STF202 is suitable for use in USB hubs,
computers, peripherals, and portable devices.
Applications
Mechanical Characteristics
USB Hubs
Portable electronics
Cellular Handsets
Modems
Peripherals
Servers, Desktop, Notebook, and Handheld
Computers
Bidirectional EMI/RFI filtering and line termination
with integrated ESD protection
ESD protection for USB power (VBUS) 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
EIAJ SOT23 6L package
Molding compound flammability rating: UL 94V-0
Marking : Marking Code
Packaging : Tape and Reel per EIA 481
S0T23-6L (Top View)
Circuit Diagram
.
22004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Absolute Maximum Rating
Electrical Characteristics
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32004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Typical Characteristics
ESD Clamping (8kV Contact) ESD Clamping (15kV Air)
Typical Insertion Loss
0.030MHz 2.0GHz
0 dB
-10 dB
-20 dB
Analog Crosstalk (D+ to D-)
0.030 MH
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-20 dB
-60 dB
42004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Figure 1 - STF202 Circuit Diagram
Device Connection
The STF202 is designed to provide termination, EMI
filtering and ESD protection for two USB I/O lines. The
equivalent circuit diagram is shown in Figure 1. The
device is connected as follows:
1.1.
1.1.
1. Full-Speed Devices: For full-speed devices the pull-
up resistor is connected to the D+ line. Pin 1 is
connected to the voltage supply line (VBUS). The
input of the D+ line is routed into pin 3 and out of
pin 4. The input of the D- line is connected at pin 2
and the output at pin 5. Pin 6 is connected to
ground.
2.2.
2.2.
2. Low-Speed Devices: For low speed devices the
pull-up resistor is connected to the D- line. Pins 1
is connected to the voltage supply line (VBUS). The
input of the D- line is connected at pin 3 with the
output taken at pin 4. The input of the D+ line is
connected to pin 2 and the output is at pin 5. Pin
6 is connected to ground.
USB Port Design Considerations
The Universal Serial Bus (USB) specification requires
termination and filtering components for proper opera-
tion. In addition, an open USB socket is vulnerable to
hazardous ESD discharges in excess of 15kV. These
discharges can may occur on the data lines or the
voltage bus. The STF202 is an easily implemented
solution designed to meet the termination and EMI
filter requirements of the USB specification revision
1.1. It also provides ESD protection to IEC 61000-4-2,
level 4.
A simplified USB port is shown in Figure 3. USB line
termination is achieved with series resistors on both
the D+ and D- lines. These resistors preserve signal
integrity by matching the cable impedance to that of
the differential driver. 15k pull-down resistors are
used to identify a downstream port while an upstream
port is identified with a 1.5K pull up resistor on either
the D+ (full speed devices) or the D- (low speed de-
vices) data line. Capacitors are used to bypass high
frequency energy to ground and for edge rate control
of the USB signals. TVS diodes are added for ESD
protection of both (D+ and D-) data lines and the
voltage bus (VBUS). A power distribution switch and
voltage regulator provide the power management
functions of the port.
Figure 2 - STF202 Connection Diagram
(Full Speed Devices)
Semtech provides a complete solution to simplify USB
port design (Figure 4). The STF201 and STF202
integrate all of the components necessary for line
termination, bidirectional EMI filtering, and ESD protec-
tion on downstream (STF201) or upstream (STF202)
ports. The SC5826 is a dual port power switch that
provides individual or ganged port switching, fault
reporting, and inrush current limiting as required by the
USB specification. The SC5205 ULDO provides a
stable voltage to the USB controller.
Board Placement and Layout Guidelines.
Designing a USB hub to meet EMI and ESD immunity
requirements requires a combination of optimum
component placement, trace routing, and good circuit
design practices. Some general guidelines are given
below:
zAvoid running D+ and D- signal line traces near high
speed clock lines or similar signal lines.
zAvoid running critical signal lines near board edges.
zLocate the USB controller chip near the USB
connectors.
zPlace the STF202 near the USB connector to
restrict transient coupling.
zMinimize the path length between the USB connec-
tor and the STF202
1
2
34
5
6
.
Applications Information
52004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Figure 3 - USB Port Components
Figure 4 - Typical USB Hub Design
Applications Information
62004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Outline Drawing - SOT23 6L
Land Pattern -SOT23 6L
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NOTES:
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SIDE VIEW
THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
NOTES:
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72004 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
PROTECTION PRODUCTS
STF202-22 and STF202-30
Contact Information
Semtech Corporation
Protection Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805)498-2111 FAX (805)498-3804
Marking Codes
Ordering Information
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