Application information ITAxxB3
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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 Ta bl e 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 BE
PROTECTED
GND
Output 1
