USB Downstream Port Filter & TVS
For EMI Filtering and ESD Protection
PROTECTION PRODUCTS - EMIClamp
®
Description
The EClamp
®
2122S is combination EMI filter and line
termination device with integrated TVS diodes for use
on USB 2.0 interfaces. This device utilizes solid-state
silicon-avalanche technology for superior clamping
performance and DC electrical characteristics. They
have been optimized for protection of USB inter-
faces in cellular phones and other portable electron-
ics.
USB line termination is achieved with a series 22Ω
resistor 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 15kΩ
pull-down resistors complete the termination circuit on
each line. They are required by the USB specification
to identify the line as a downstream connection. The
capacitors are used to bypass high frequency energy to
ground and for edge rate control of the USB signals.
Integrated TVS diodes provide 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 25kV (air discharge) and 20kV
(contact discharge) per IEC 61000-4-2.
The EClamp2122S is in a 6-pin SOT-23 package. The
leads are finished with lead-free matte tin. It is suit-
able for use in USB hubs, computers, peripherals, and
portable devices
EClamp2122S
Features
EMI/RFI filtering and line termination with inte-
grated ESD protection
ESD protection for USB power (V
BUS
) and data lines
(D+ & D-) to
IIEC 61000-4-2 (ESD), ±25kV (air),
±20kV (contact)
Filtering and termination for two USB data lines
Series resistors for impedance matching
Integrated pull down resistors as required by the
USB specification for downstream ports
Low TVS operating voltage (5.25V)
Solid-state technology
Mechanical Characteristics
JEDEC SOT-23 6L package
Pb-Free, Halogen Free, RoHS/WEEE Compliant
Nominal Dimensions: 2.9 x 2.8mm
Molding compound flammability rating: UL 94V-0
Marking: Marking Code + Date Code
Packaging: Tape and Reel
Applications
USB 1.1 Interfaces
USB Hubs
Printers
Monitors
Servers, Desktop, and Notebook computers
Circuit Diagram
Pin Configuration
C1
C2
C1
C2
(Top Side View)
Revision 1/24/2011
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EClamp2122S
PROTECTION PRODUCTS
Absolute Maximum Rating
R ating
Steady-State Power
ESD Air Discharge per IEC 61000-4-2
ESD Contact Discharge per IEC 61000-4-2
Operating Temperature
Storage Temperature
Symbol
P
SS
V
ESD
T
J
T
STG
Value
100
25
20
-40 to +85
-55 to +150
Units
mW
kV
°C
°C
Electrical Characteristics (T = 25
o
C)
Parameter
T VS Reverse Stand-Off Voltage
T VS Reverse Breakdown Voltage
Series Resistance
Pulldown Resistance
T VS Diode Capacitance
Total Capacitance
Symbol
V
RWM
V
BR
R
S
R
PD
C
C
TOT
Conditions
Minimum
Typical
Maximum
5.25
Units
V
V
I
t
= 1mA
Each Line
Each Line
Each Line
V
R
= 0V, f = 1MHz
Between Input or Output
to Ground
V
R
= 0V, f = 1MHz
6
20
13.5
27
22
15
30
50
24
16.5
33
Ω
kΩ
pF
pF
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2011 Semtech Corp.
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EClamp2122S
PROTECTION PRODUCTS
Typical Characteristics
ESD Clamping (Pin 1 to GND)
(8kV Contact per IEC 61000-4-2)
ESD Clamping (Pin 1 to GND)
(-8kV Contact per IEC 61000-4-2)
ESD Clamping (Pin 4 or 5 to GND)
(8kV Contact per IEC 61000-4-2)
ESD Clamping (Pin 4 or 5 to GND)
(-8kV Contact per IEC 61000-4-2)
Note: ESD data is taken with a 20dB attenuator
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2011 Semtech Corp.
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EClamp2122S
PROTECTION PRODUCTS
Typical Insertion Loss S21
(Pin 2 to 5 with respect to GND)
Typical Insertion Loss S21
(Pin 3 to 4 with respect to GND)
Frequency
114.9MHz
800MHz
900MHz
1.8GHz
2.5GHz
2.7GHz
S21 (dB)
-3.00
-14.11
-11.62
-5.16
-3.55
-3.52
Frequency S21 (dB)
114.6MHz
-3.00
800MHz
-12.58
900MHz
-10.40
1.8GHz
-4.76
2.5GHz
-3.30
2.7GHz
-3.38
Normalized Junction Capacitance
vs. Reverse Voltage (Data Pins)
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
0
1
2
3
Reverse Voltage - V
R
(V)
4
C
J
(V
R
) / C
J
(V
R
=0)
f = 1 MHz
5
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2011 Semtech Corp.
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EClamp2122S
PROTECTION PRODUCTS
Applications Information
Device Connection
The EClamp2122S 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:
USB data lines are routed through the
EClamp2122S for easy implementation and opti-
mum pc board layout. Pin 1 is connected to the
voltage supply line. The input of the D+ line is
routed into pin 2 and out of pin 5. The input of the
D- line is connected at pin 3 and the output at pin
4. Pin 6 is connected to ground. The ground
connection should be made directly to the ground
plane for best results. The path length is kept as
short as possible to reduce the effects of parasitic
inductance in the board traces.
USB Port Design with EClamp2122S
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 occur on the data lines or the voltage
bus. The EClamp2122S 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.
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 resis-
tors are used to identify a downstream port. Capaci-
tors are used to bypass high frequency energy to
ground and for edge rate control of the USB signals.
Integrated TVS diodes provide ESD protection of both
(D+ & D-) data lines and the voltage bus (V
BUS
).
General layout 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.
Place the EClamp2122S near the USB connector
to restrict transient coupling.
Minimize the path length between the USB connec-
tor and the EClamp2122S.
C1
C2
Figure 1 - EClam p2122S Cir cuit Diagram
EClamp2
p2122S Circuit
C1
C2
©
2011 Semtech Corp.
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