STF202-22
USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection
Objective - March 03, 2000
&
STF202-30
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.Semtech.com
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 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
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.
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
ORDERING INFORMATION
Part Number
STF202-22.TC
STF202-30.TC
Series
Resistor
22
Ω
30
Ω
Qty per
Reel
3,000
3,000
Reel Size
7”
7”
COMPONENT VALUES
Series
Resistor
(R
S
)
STF202-22
STF202-30
Tolerance
22
Ω
30
Ω
±10%
Pull Up
Resistor
(R
PU
)
1.5k
Ω
1.5k
Ω
±10%
Termination
Capacitor
(C)
47
47
±20%
SCHEMATIC & PIN CONFIGURATION
SOT-23 6L (Top View)
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
STF202-22
USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection
Objective - March 03, 2000
&
STF202-30
MAXIMUM RATINGS
Rating
Steady-State Power
ESD Air Discharge per IEC 1000-4-2
ESD Contact Discharge per IEC 1000-4-2
Lead Soldering Temperature (10 seconds)
Operating Temperature
Storage Temperature
Symbol
P
V
PP
V
PP
T
L
T
stg
T
j
Value
100
16
10
260
-40 to +125
-55 to +150
Unit
mW
kV
kV
°C
°C
°C
ELECTRICAL CHARACTERISTICS (T = 25ºC Unless Otherwise Noted)
STF202-xx
Parameter
TVS Reverse Stand-Off Voltage
TVS Reverse Breakdown Voltage
TVS Reverse Leakage Current
Symbol
V
RWM
V
BR
I
R
I
t
= 1mA
V
RWM
= 5.25V, T=25°C
Between V
BUS
pin and
ground
V
RWM
= 3.3V, T=25°C
Between any data
(D+, D-) pin and ground
Between I/O pins and
Gnd, each device
V
R
= 0V, f = 1MHz
Each Line
Each Line
Each Line
Each Line
Between I/O pins and
Gnd, each line
V
R
= 0V, f = 1MHz
20
27
1.35
10
6
5
Conditions
Minimum
Nominal
Maximum
5.25
Units
V
V
µA
TVS Reverse Leakage Current
I
R
1
µA
Total TVS Junction Capacitance
C
j
pF
Series Resistor
(STF202-22)
Series Resistor
(STF202-30)
Pull Up Resistor
Capacitor
Total Capacitance
R
S
R
S
R
UP
C
C
TOT
22
30
1.5
47
60
24
33
1.65
Ω
Ω
kΩ
pF
pF
MARKING CODES
Part Number Marking Code
STF202-22
STF202-30
222
230
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
STF202-22
USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection
Objective - March 03, 2000
&
STF202-30
TYPICAL CHARACTERISTICS
ESD Clamping (8kV Contact)
ESD Clamping (15kV Air)
Insertion Loss Characteristics
Analog Crosstalk (D+ to D-)
0 dB
0 dB
-20 dB
-10 dB
-60 dB
-20 dB
0.030MHz
2.0GHz
0.030 MHz
1 GHz
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
STF202-22
USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection
Objective - March 03, 2000
&
STF202-30
APPLICATIONS INFORMATION
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.
Figure 1 - STF202 Circuit Diagram
.
•
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.
Figure 2 - STF202 Connection Diagram
(Full Speed Devices)
1
2
3
6
5
4
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. 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 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
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
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
STF202-22
USB Upstream Port Filter & TVS
For EMI Filtering and ESD Protection
Objective - March 03, 2000
&
STF202-30
APPLICATIONS INFORMATION
Figure 3 - USB Port Components
Figure 4 - Typical USB Hub Design
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
