Transient Voltage Suppressors Array for ESD Protection
SRV05-4
Applications Information (Continue)
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.
Low Capacitance
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.
Figure 7 . Digital Video Interface (DVI) Protection
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 theprotected 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.
UN Semiconductor Co., Ltd.
Revision January 06, 2014
6/7
@ UN Semiconductor Co., Ltd. 2014
Specifications are subject to change without notice.
Please refer to www.unsemi.com.tw for current information.
UNSEMI [ UN Semiconducctor INC ]
