ESDR7534 Datasheet, PDF (4/5 Pages) ON Semiconductor – Low Capacitance TVS for LVDS Interfaces

ESDR7534
APPLICATIONS INFORMATION
The new ESDR7534 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 ESDR7534 offers low capacitance steering
diodes and an internal TVS diode (V_P diode) integrated in
a single package. 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.
ESDR7534 Configuration Options
The ESDR7534 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 (V_f or
V_CC + V_f). 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. This pin 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 2
Protection of four data lines with bias and power supply
isolation resistor.
I/O 1
I/O 2
1
2
V_CC
6
10 k
5
3
4
I/O 3
I/O 4
The ESDR7534 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 V_P and steering diodes, reducing their
capacitance.
Option 3
Protection of four data lines using the V_P diode as
reference.
I/O 1
I/O 2
Option 1
Protection of four data lines and the power supply using
V_CC as reference.
1
6
2
5
NC
I/O 1
I/O 2
1
2
3
I/O 3
I/O 4
3
4
I/O 3
6
I/O 4
5
V_CC
In applications lacking a positive supply reference or
those cases in which a fully isolated power supply is
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required, the V_P 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 V_BR of the I/O (CHX) pin.
For this configuration, connect pin 5 directly to the
positive supply rail (V_CC), the data lines are referenced to
the supply voltage. The V_P diode prevents overvoltage on
the supply rail. Biasing of the steering diodes reduces their
capacitance.
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