652 MITCHELL ROAD NEWBURY PARK CA 91320

Objective - March 03, 2000

USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection

STF202-22

STF202-30

SCHEMATIC & PIN CONFIGURATION

FEATURES

Bidirectional EMI/RFI filtering and line termination
with integrated ESD protection

ESD protection for USB power (V

BUS

) and data

lines (D+ & D-) to IEC 1000-4-2 Level 4

Filtering and termination for two USB data lines

Different series resistors for impedance matching

Low TVS operating voltage (5.25V)

Low leakage current

Small SOT-23 6L package

Solid-state technology

MECHANICAL CHARACTERISTICS

EIAJ SOT-23 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

Peripherals

Servers, Desktop, Notebook, and Handheld
Computers

DESCRIPTION

The STF202 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
STF202 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 22

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
specification 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
contains TVS diodes for ESD protection of both (D+ &
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 1000-4-2, 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.

TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.Semtech.com

Part Number

Series

Resistor

Qty per

Reel

Reel Size

STF202-22.TC

3,000

STF202-30.TC

3,000

ORDERING INFORMATION

SOT-23 6L (Top View)

COMPONENT VALUES

Series

Resistor

)

Pull Up

Resistor

)

Termination

Capacitor

(C)

STF202-22

1.5k

STF202-30

1.5k

Tolerance

±10%

±20%

652 MITCHELL ROAD NEWBURY PARK CA 91320

Objective - March 03, 2000

USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection

STF202-22

STF202-30

MAXIMUM RATINGS

Rating

Symbol

Value

Unit

Steady-State Power

100

ESD Air Discharge per IEC 1000-4-2

ESD Contact Discharge per IEC 1000-4-2

Lead Soldering Temperature (10 seconds)

260

°C

Operating Temperature

stg

-40 to +125

°C

Storage Temperature

-55 to +150

°C

ELECTRICAL CHARACTERISTICS (T = 25ºC Unless Otherwise Noted)

STF202-xx

Parameter

Symbol

Conditions

Minimum

Nominal

Maximum

Units

TVS Reverse Stand-Off Voltage

RWM

5.25

TVS Reverse Breakdown Voltage

= 1mA

TVS Reverse Leakage Current

RWM

= 5.25V, T=25°C

Between V

BUS

pin and

ground

µA

TVS Reverse Leakage Current

RWM

= 3.3V, T=25°C

Between any data

(D+, D-) pin and ground

µA

Total TVS Junction Capacitance

Between I/O pins and

Gnd, each device

= 0V, f = 1MHz

Series Resistor (STF202-22)

Each Line

Series Resistor (STF202-30)

Each Line

Pull Up Resistor

Each Line

1.35

1.5

1.65

Capacitor

Each Line

Total Capacitance

TOT

Between I/O pins and

Gnd, each line

= 0V, f = 1MHz

Part Number Marking Code

STF202-22

222

STF202-30

230

MARKING CODES

652 MITCHELL ROAD NEWBURY PARK CA 91320

Objective - March 03, 2000

USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection

STF202-22

STF202-30

APPLICATIONS INFORMATION

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. 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 (V

BUS

). 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.

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 (V

BUS

). 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
operation. 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
& 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 devices) 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+ & D-) data lines and the voltage bus (V

BUS

). A

power distribution switch and voltage regulator provide
the power management functions of the port.

Semtech provides a complete solution to simplify USB
port design (Figure 4). The STF201 & STF202

Figure 2 - STF202 Connection Diagram

(Full Speed Devices)

integrate all of the components necessary for line
termination, bidirectional EMI filtering, and ESD
protection 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 & Layout Guidelines.
Designing a USB hub to meet EMI & ESD immunity
requirements requires a combination of optimum
component placement, trace routing, and good circuit
design practices. Some general guidelines are given
below:

Avoid running D+ & D- signal line traces near high
speed clock lines or similar signal lines.

Avoid running critical signal lines near board
edges.

Locate the USB controller chip near the USB
connectors.

Place the STF202 near the USB connector to
restrict transient coupling.

Minimize the path length between the USB
connector and the STF202

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ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: STF202-22