NUP4202W1

http://onsemi.com

3

APPLICATIONS INFORMATION

The new NUP4202W1 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 NUP4202W1 offers surge rated, low

capacitance steering diodes and a TVS diode integrated in a

single package (SC−88). 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.

NUP4202W1 Configuration Options

The NUP4202W1 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 Vcc+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. 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 1

Protection of four data lines and the power supply using

Vcc as reference.

6

5

4

1

2

3

I/O 1

I/O 2

I/O 3

I/O 4

For this configuration, connect pin 5 directly to the

positive supply rail (Vcc), 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.

10 k

6

5

4

1

2

3

I/O 1

I/O 2

I/O 3

I/O 4

The NUP4202W1 can be isolated from the power supply

by connecting a series resistor between pin 5 and Vcc. A

10 k

W 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

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: