SRV05−4MR6
http://onsemi.com
5
APPLICATIONS INFORMATION
The new SRV05−4MR6 is a low capacitance TVS diode
array designed to protect sensitive electronics such as
communications systems, computers, and computer
peripherals against damage due to ESD events or transient
overvoltage conditions. Because of its low capacitance, it
can be used in high speed I/O data lines. The integrated
design of the SRV05−4MR6 offers surge rated, low
capacitance steering diodes and a TVS diode integrated in a
single package (TSOP−6). If a transient condition occurs,
the steering diodes will drive the transient to the positive rail
of the power supply or to ground. The TVS device protects
the power line against overvoltage conditions to avoid
damage to the power supply and any downstream
components.
SRV05−4MR6 Configuration Options
The SRV05−4MR6 is able to protect up to four data lines
against transient overvoltage conditions by driving them to
a fixed reference point for clamping purposes. The steering
diodes will be forward biased whenever the voltage on the
protected line exceeds the reference voltage (Vf or V
CC
+
Vf). The diodes will force the transient current to bypass the
sensitive circuit.
Data lines are connected at pins 1, 3, 4 and 6. The negative
reference is connected at pin 2. These pins must be
connected directly to ground by using a ground plane to
minimize the PCB’s ground inductance. It is very important
to reduce the PCB trace lengths as much as possible to
minimize parasitic inductances.
Option 1
Protection of four data lines and the power supply using
V
CC
as reference.
6
5
4
1
2
3
I/O 1
I/O 2
I/O 3
I/O 4
V
CC
For this configuration, connect pin 5 directly to the
positive supply rail (V
CC
), the data lines are referenced to
the supply voltage. The internal TVS diode prevents
overvoltage on the supply rail. Biasing of the steering diodes
reduces their capacitance.
Option 2
Protection of four data lines with bias and power supply
isolation resistor.
V
CC
10 k
6
5
4
1
2
3
I/O 1
I/O 2
I/O 3
I/O 4
The SRV05−4MR6 can be isolated from the power supply
by connecting a series resistor between pin 5 and V
CC
. A
10 kW resistor is recommended for this application. This
will maintain a bias on the internal TVS and steering diodes,
reducing their capacitance.
Option 3
Protection of four data lines using the internal TVS diode
as reference.
6
5
4
1
2
3
I/O 1
I/O 2
I/O 3
I/O 4
NC
In applications lacking a positive supply reference or
those cases in which a fully isolated power supply is
required, the internal TVS can be used as the reference. For
these applications, pin 5 is not connected. In this
configuration, the steering diodes will conduct whenever the
voltage on the protected line exceeds the working voltage of
the TVS plus one diode drop (Vc = Vf + V
TVS
).
ESD Protection of Power Supply Lines
When using diodes for data line protection, referencing to
a supply rail provides advantages. Biasing the diodes
reduces their capacitance and minimizes signal distortion.
Implementing this topology with discrete devices does have
disadvantages. This configuration is shown below:
