CLT3-4BT6

3/10

The CLTx-4 is a quadruple input digital termination device designed for 24 V DC automation applications. It

achieves the front-end circuitry of a digital input module (I/O) in industrial automation, and drives an

isolating opto-coupler.

Available in a four channels configuration, it offers a high-density termination by minimizing the external

components count. It is housed in a TSSOP20 surface mount package to reduce the printed board size.

Made of an input voltage protection, a serial current limiting circuit and an opto-coupler driver, each

channel circuit terminates the connection between the logic input and the associated high side sensor or

switch.

The CLT3-4 isa3mA quad channel device compatible the type 1 characteristics of the IEC61131-2

standard.

Each input voltage clamping block protects the module input against electromagnetic interferences such

as those described in the IEC61131-2 standard and IEC61000-4-2 (ESD), 4-4 (transient burst), 4-5

(voltage surge) standards. The supply input is also designed with such a protection structure.

The current limiting circuit connected between the input and the output pins is compensated all over the

temperature range. Thanks to its low tolerance, the current limitation allows reducing drastically the

dissipation of the input compared to a resistive input: the overall module requires less cooling capability

and becomes smaller.

The output block of each termination channel controls the operation of an opto-coupler that is enabled by a

Light Emitting Diode.

When the input current is less than 1.5 mA, this output circuit derivates the input current to maintain the

opto-coupler off.

The original structure of the CLT limiter allows its activation threshold to be low and insensitive to the

output voltage up to a maximum value of 2.0 V.

Ω, the output current that is a share of the input current

(3/4) is higher than 1.5 mA. The whole termination channel including the opto-coupler is on.

FUNCTIONAL DESCRIPTION

Symbol

Pin

Parameter name & conditions

Value

Unit

Ω

- 0.3 to 30

V

Ω

- 0.3 to 35

V

(1)

IN

Ω

- 0.3 to 30

V

Ω

- 0.3 to 32

V

Ω

- 0.3 to 35

V

Input repetitive pulse voltage,

-30to30

V

IN

Input maximum forward current,

5mA

Input maximum reverse current,

20

mA

OUT

Maximum output steady state voltage

2.5

V

OUT

Output current

- 4 to 4

mA

AII

Operating ambient temperature

- 25 to 85

°C

Operating and storage junction temperature

- 25 to 150

°C

Note 1: VI =VIN +RI xIIN;VIN = voltage at the input pin itself

Note 2: according to test diagram on figure 8, this case covers especially the reverse polarity operation of one input.

ABSOLUTE RATINGS (limiting values)