STF202-22.TCT - Semtech - Product.Network

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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 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 (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

2 2004 Semtech Corp. www.semtech.com

PROTECTION PRODUCTS

STF202-22 and STF202-30

Absolute Maximum Rating

Electrical Characteristics

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3 2004 Semtech Corp. www.semtech.com

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

1 GH

0 dB

-20 dB

-60 dB

4 2004 Semtech Corp. www.semtech.com

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. 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. 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. 15kΩ pull-down resistors are

used to identify a downstream port while an upstream

port is identified with a 1.5KΩ 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

Applications Information

5 2004 Semtech Corp. www.semtech.com

PROTECTION PRODUCTS

STF202-22 and STF202-30

Figure 3 - USB Port Components

Figure 4 - Typical USB Hub Design

Applications Information

6 2004 Semtech Corp. www.semtech.com

PROTECTION PRODUCTS

STF202-22 and STF202-30

Outline Drawing - SOT23 6L

Land Pattern -SOT23 6L

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DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS3.

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NOTES:

2. -A- -B- -H-

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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7 2004 Semtech Corp. www.semtech.com

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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22-202FTS222

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TCT.03-202FTSeerfbP000,3hcnI7