1www.semtech.com
PROTECTION PRODUCTS
SRV05-4
RailClamp
Low Capacitance TVS Diode Array
Description Features
Circuit Diagram Schematic and PIN Configuration
Revision 01/18/2008
RailClamps are surge rated diode arrays designed to
protect high speed data interfaces. The SR series has
been specifically designed to protect sensitive compo-
nents which are connected to data and transmission
lines from overvoltage caused by electrostatic dis-
charge (ESD), electrical fast transients (EFT), and
lightning.
The unique design of the SR series devices incorpo-
rates eight surge rated, low capacitance steering
diodes and a TVS diode in a single package. During
transient conditions, the steering diodes direct the
transient to either the positive side of the power supply
line or to ground. The internal TVS diode prevents
over-voltage on the power line, protecting any down-
stream components.
The SRV05-4 has a low typical capacitance of 3pF and
operates with virtually no insertion loss to 1GHz. This
makes the device ideal for protection of high-speed
data lines such as USB 2.0, Firewire, DVI, and gigabit
Ethernet interfaces.
The low capacitance array configuration allows the user
to protect four high-speed data or transmission lines.
The low inductance construction minimizes voltage
overshoot during high current surges. They may be
used to meet the ESD immunity requirements of IEC
61000-4-2, Level 4 (±15kV air, ±8kV contact dis-
charge).
Applications
Mechanical Characteristics
USB 2.0 Power and Data Line Protection
Video Graphics Cards
Monitors and Flat Panel Displays
Digital Video Interface (DVI)
10/100/1000 Ethernet
Notebook Computers
SIM Ports
ATM Interfaces
IEEE 1394 Firewire Ports
ESD protection for high-speed data lines to
IEC 61000-4-2 (ESD) ±15kV (air), ±8kV (contact)
IEC 61000-4-4 (EFT) 40A (5/50ns)
IEC 61000-4-5 (Lightning) 12A (8/20µs)
Array of surge rated diodes with internal TVS Diode
Small package saves board space
Protects four I/O lines
Low capacitance: 3pF typical
Low clamping voltage
Low operating voltage: 5.0V
Solid-state silicon-avalanche technology
JEDEC SOT-23 6L package
Molding compound flammability rating: UL 94V-0
Marking : V05
Packaging : Tape and Reel
SOT-23 6L (Top View)
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22008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Absolute Maximum Rating
Electrical Characteristics
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32008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Typical Characteristics
Non-Repetitive Peak Pulse Power vs. Pulse Time Power Derating Curve
0
10
20
30
40
50
60
70
80
90
100
110
0 25 50 75 100 125 150
Ambient Temperature - TA (oC)
% of Rated Power or I
PP
Clamping Voltage vs. Peak Pulse CurrentPulse Waveform
Forward Voltage vs. Forward Current Normalized Capacitance vs. Reverse Voltage
0.00
5.00
10.00
15.00
20.00
25.00
30.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00
Peak Pulse Current - IPP (A)
Clamping Voltage -VC (V)
Waveform
Parameters:
tr = 8µs
td = 20µs
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
0.00 2.00 4.00 6.00 8.00 10.00 12.00
Forward Current - IF (A)
Forward Voltage -VF (V)
Waveform
Parameters:
tr = 8µs
td = 20µs
0.01
0.1
1
10
0.1 1 10 100 1000
Pulse Duration - tp (µs)
Peak Pulse Power - PPk (kW)
0
10
20
30
40
50
60
70
80
90
100
110
0 5 10 15 20 25 30
Time (µs)
Percent of I PP
e-t
td = IPP/2
Waveform
Parameters:
tr = 8µs
td = 20µs
0
0.2
0.4
0.6
0.8
1
1.2
1.4
012345
Reverse Voltage - VR (V)
CJ(VR) / CJ(VR=0)
f = 1 MHz
42008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
3 dB/
CH1 S21 LOG REF 0 dB
START .030 000 MHz STOP 3 000.000 000 MHz
CH1 S21 LOG 20 dB/ REF 0 dB
START .030 000 MHz STOP 3 000.000 000 MHz
Insertion Loss S21 Analog Cross Talk
Applications Information
52008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Device Connection Options for Protection of Four
High-Speed Data Lines
The SRV05-4 TVS is designed to protect four data lines
from transient over-voltages by clamping them to a
fixed reference. When the voltage on the protected
line exceeds the reference voltage (plus diode VF) the
steering diodes are forward biased, conducting the
transient current away from the sensitive circuitry.
Data lines are connected at pins 1, 3, 4 and 6. The
negative reference (REF1) is connected at pin 2. This
pin should be connected directly to a ground plane on
the board for best results. The path length is kept as
short as possible to minimize parasitic inductance.
The positive reference (REF2) is connected at pin 5.
The options for connecting the positive reference are
as follows:
1. To protect data lines and the power line, connect
pin 5 directly to the positive supply rail (VCC). In this
configuration the data lines are referenced to the
supply voltage. The internal TVS diode prevents
over-voltage on the supply rail.
2. The SRV05-4 can be isolated from the power
supply by adding a series resistor between pin 5
and VCC. A value of 100kΩ is recommended. The
internal TVS and steering diodes remain biased,
providing the advantage of lower capacitance.
3. In applications where no positive supply reference
is available, or complete supply isolation is desired,
the internal TVS may be used as the reference. In
this case, pin 5 is not connected. The steering
diodes will begin to conduct when the voltage on
the protected line exceeds the working voltage of
the TVS (plus one diode drop).
ESD Protection With RailClamps
RailClamps are optimized for ESD protection using the
rail-to-rail topology. Along with good board layout,
these devices virtually eliminate the disadvantages of
using discrete components to implement this topology.
Consider the situation shown in Figure 1 where dis-
crete diodes or diode arrays are configured for rail-to-
rail protection on a high speed line. During positive
duration ESD events, the top diode will be forward
biased when the voltage on the protected line exceeds
Data Line and Power Supply Protection Using Vcc as
reference
Data Line Protection with Bias and Power Supply
Isolation Resistor
Data Line Protection Using Internal TVS Diode as
Reference
Applications Information
62008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
PIN Descriptions
the reference voltage plus the VF drop of the diode.
For negative events, the bottom diode will be biased
when the voltage exceeds the VF of the diode. At first
approximation, the clamping voltage due to the charac-
teristics of the protection diodes is given by:
VC = VCC + VF(for positive duration pulses)
VC = -VF(for negative duration pulses)
However, for fast rise time transient events, the
effects of parasitic inductance must also be consid-
ered as shown in Figure 2. Therefore, the actual
clamping voltage seen by the protected circuit will be:
VC = VCC + VF + LP diESD/dt (for positive duration pulses)
VC = -VF - LG diESD/dt (for negative duration pulses)
ESD current reaches a peak amplitude of 30A in 1ns
for a level 4 ESD contact discharge per IEC 61000-4-2.
Therefore, the voltage overshoot due to 1nH of series
inductance is:
V = LP diESD/dt = 1X10-9 (30 / 1X10-9) = 30V
Example:
Consider a VCC = 5V, a typical VF of 30V (at 30A) for the
steering diode and a series trace inductance of 10nH.
The clamping voltage seen by the protected IC for a
positive 8kV (30A) ESD pulse will be:
VC = 5V + 30V + (10nH X 30V/nH) = 335V
This does not take into account that the ESD current is
directed into the supply rail, potentially damaging any
components that are attached to that rail. Also note
that it is not uncommon for the VF of discrete diodes to
exceed the damage threshold of the protected IC. This
is due to the relatively small junction area of typical
discrete components. It is also possible that the
power dissipation capability of the discrete diode will
be exceeded, thus destroying the device.
The RailClamp is designed to overcome the inherent
disadvantages of using discrete signal diodes for ESD
suppression. The RailClamp’s integrated TVS diode
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Figure 2 - The Effects of Parasitic InductanceFigure 2 - The Effects of Parasitic Inductance
Figure 2 - The Effects of Parasitic Inductance
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Applications Information (continued)
72008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Applications Information (continued)
helps to mitigate the effects of parasitic inductance in
the power supply connection. During an ESD event,
the current will be directed through the integrated TVS
diode to ground. The maximum voltage seen by the
protected IC due to this path will be the clamping
voltage of the device.
Video Interface Protection
Video interfaces are susceptible to transient voltages
resulting from electrostatic discharge (ESD) and “hot
plugging” cables. If left unprotected, the video
interface IC may be damaged or even destroyed.
Protecting a high-speed video port presents some
unique challenges. First, any added protection device
must have extremely low capacitance and low leakage
current so that the integrity of the video signal is not
compromised. Second, the protection component
must be able to absorb high voltage transients without
damage or degradation. As a minimum, the device
should be rated to handle ESD voltages per IEC
61000-4-2, level 4 (±15kV air, ±8kV contact). The
clamping voltage of the device (when conducting high
current ESD pulses) must be sufficiently low enough to
protect the sensitive CMOS IC. If the clamping voltage
is too high, the “protected” device may latch-up or be
destroyed. Finally, the device must take up a relatively
small amount of board space, particularly in portable
applications such as notebooks and handhelds. The
SRV05-4 is designed to meet or exceed all of the
above criteria. A typical video interface protection
circuit is shown in Figure 4. All exposed lines are
protected including R, G, B, H-Sync, V-Sync , and the ID
lines for plug and play monitors.
Universal Serial Bus ESD Protection
The SRV05-4 may also be used to protect the USB
ports on monitors, computers, peripherals or portable
systems. Each device will protect up to two USB ports
(Figure 5). When the voltage on the data lines exceed
the bus voltage (plus one diode drop), the internal
rectifiers are forward biased conducting the transient
current away from the protected controller chip. The
TVS diode directs the surge to ground. The TVS diode
also acts to suppress ESD strikes directly on the
voltage bus. Thus, both power and data pins are
protected with a single device.
SRV05-4
Figure 4 - Video Interface Protection
Figure 5 - Dual USB Port Protection
Figure 6 - SIM Port
82008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Figure 7 - Digital Video Interface (DVI) Protection
DVI Protection
The small geometry of a typical digital-visual interface
(DVI) graphic chip will make it more susceptible to
electrostatic discharges (ESD) and cable discharge
events (CDE). Transient protection of a DVI port can
be challenging. Digital-visual interfaces can often
transmit and receive at a rate equal to or above
1Gbps. The high-speed data transmission requires the
protection device to have low capacitance to maintain
signal integrity and low clamping voltage to reduce
stress on the protected IC. The SRV05-4 has a low
typical insertion loss of <0.4dB at 1GHz (I/O to ground)
to ensure signal integrity and can protect the DVI
interface to the 8kV contact and 15kV air ESD per IEC
61000-4-2 and CDE.
Figure 7 shows how to design the SRV05-4 into the
DVI circuit on a flat panel display and a PC graphic
card. The SRV05-4 is configured to provide common
mode and differential mode protection. The internal
TVS of the SRV05-4 acts as a 5 volt reference. The
power pin of the DVI circuit does not come out through
the connector and is not subjected to external ESD
pulse; therefore, pin 5 should be left unconnected.
Connecting pin 5 to Vcc of the DVI circuit may result in
damage to the chip from ESD current.
10/100 ETHERNET PROTECTION
Ethernet ICs are vulnerable to damage from electro-
static discharge (ESD). The internal protection in the
PHY chip, if any, often is not enough due to the high
energy of the discharges specified by IEC 61000-4-2.
If the discharge is catastrophic, it will destroy the
protected IC. If it is less severe, it will cause latent
failures that are very difficult to find.
10/100 Ethernet operates at 125MHz clock over a
twisted pair interface. In a typical system, the twisted-
pair interface for each port consists of two differential
signal pairs: one for the transmitter and one for the
receiver, with the transmitter input being the most
sensitive to damage. The fatal discharge occurs
differentially across the transmit or receive line pair
and is capacitively coupled through the transformer to
the Ethernet chip. Figure 8 shows how to design the
SRV05-4 on the line side of a 10/100 ethernet port to
provide differential mode protection. The common
mode isolation of the transformer will provide common
mode protection to the rating of the transformer
isolation which is usually >1.5kV. If more common
mode protection is needed, figure 9 shows how to
design the SRV05-4 on the IC side of the 10/100
92008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
SRV05-4
Figure 8 - 10/100 Ethernet Differential Protection
Figure 9 - 10/100 Ethernet Differential and Common Mode Protection
102008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
10/100 ETHERNET PROTECTION CONT’
Ethernet circuit to provide differential and common
mode protection. The SRV05-4 can not be grounded
on the line side because the hi-pot test requires the
line side not to be grounded.
112008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Applications Information - SPICE Model
SRV05-4 Spice Model
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122008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Outline Drawing - SO-8
Land Pattern -SOT23 6L
Outline Drawing -SOT23 6L
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DATUMS AND TO BE DETERMINED AT DATUM PLANE
CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
DIMENSIONS "E1" AND "D" DO NOT INCLUDE MOLD FLASH, PROTRUSIONS3.
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THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
NOTES:
1.
132008 Semtech Corp. www.semtech.com
PROTECTION PRODUCTS
SRV05-4
Contact Information
Semtech Corporation
Protection Products Division
200 Flynn Road, Camarillo, CA 93012
Phone: (805)498-2111 FAX (805)498-3804
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Tape and Reel Specification
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User Direction of feed