4
2002 Semtech Corp.
www.semtech.com
PROTECTION PRODUCTS
SRV08-4
Device Connection Options for Protection of Four
High-Speed Data Lines
The SRV08-4 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 V
F) 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 is connected at pin 5. 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 is connected at pin 2. In this
configuration the data lines are referenced to the
supply voltage.
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
SRV08-4 is designed to meet or exceed all of the
above criteria. A typical video interface protection
circuit is shown in Figure 2. All exposed lines are
protected including R, G, B, H-Sync, V-Sync , and the ID
lines for plug and play monitors.
ESD Protection With RailClamps
RailClamps are optimized for ESD protection using the
rail-to-rail topology. Along with good board layout,
Figure 1 - Data Line and Power Supply Protection
Using Vcc as reference
Figure 2 - Video Interface Protection
Applications Information