Characteristics

CLT3-4B

4/13

Figure 3.

Typical junction to ambient thermal resistance versus copper surface

under common pad (FR4 epoxy, copper thickness is 35 µm)

1.1

Functional description

The CLT3-4 is a quadruple input digital termination device designed for 24 V DC automation

applications. It provides 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 is a 3 mA quad channel device compatible the type 1 and 3 characteristics of

the IEC 61131-2 standard.

Each input voltage clamping block protects the module input against electromagnetic

interferences such as those described in the IEC 61131-2 standard and IEC 61000-4-2

(ESD), 4-4 (transient burst), 4-5 (voltage surge) standards. The supply input is also

designed with such a protection structure.

Table 5.

CLT3 System electromagnetic compatibility ratings,

Symbol

Node

Parameter name and conditions

Value

Unit

IN

ESD protection, IEC 61000-4-2, per input, in air

± 8

kV

ESD protection, IEC 61000-4-2, per input, in contact

± 6

kV

± 3

kV

± 3

kV

Total Peak Pulse Voltage Burst, IEC 61000-4-4

(1)

1.

Refer to Application note AN2527 for test conditions.

± 4

kV

Peak Pulse Voltage Surge, IEC 61000-4-5, R = 42

2.

See test circuit in Figure 12.

± 1

kV

Peak Pulse Voltage Surge, IEC 61000-4-5, R = 2

Ω (2)

± 1

kV

0

20

40

60

80

100

120

140

160

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

S(cm²)

R

° C/W)

th(j-a)(