Application information

ITAxxB3

4/8

2

Application information

This monolithic Transil Array is based on 610 unidirectional Transils with a common cathode

and can be configurated to offer up to 9 bidirectional functions. This imposes a maximum

differential voltage between 2 input pins (see Table 3).

Figure 8.

RS-232 junction (typical application)

2.1

Design advantage of ITAxxB3 used with 4-point structure

Table 3.

Maximum differential voltages

Order code

Maximum differential voltage between two input pins at 25°C

ITA6V5B3

± 3.5 v

ITA18B3

± 9.0 v

ITA25B3

± 12.5 v

TX

DTR

DSR

CARRIER DET.

AUX

CTS

RTS

RX

GND

The ITAxxxB3 has been designed with a 4-point structure

(separated Input/output) to efficiently protect against

disturbances with very high di/dt rates, such as ESD.

The purpose of this 4-point structure is to eliminate the

overvoltage introduced by the parasitic inductances of the

wiring (Ldi/dt).

Efficient protection depends not only on the component

itself, but also on the circuit layout. The drawing given in

figure 9 shows the layout to be used in order to take

advantage of the 4-point structure of the ITAxxxB3.

With this layout, each line to be protected passes through

the protection device.

In this way, it realizes an interface between the data line

and the circuit to be protected, guaranteeing an isolation

between its inputs and outputs.

Figure 9.

The 4 point structure

U

Chip

Input 1

di/dt

GND

DEVICE

TO

B

E

PR

O

TECTED

GND

Output 1