CLT3-4BT6

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CLT3-4 INPUT / OUTPUT TRANSFER CHARACTERISTICS (respect to common pin COM)

ISOLATOR ON

ISOLATOR OFF

Forbidden

Transition zone

0

0.5

1

1.5

2

2.5

3

3.5

4

0

0.5

1

1.5

2

2.5

3

3.5

4

0.04

2.1

3.7

I

(mA)

IN

I

(mA)

OUT

Fig. 4: Current tranfer characteristic

0

0.5

1

1.5

2

2.5

3

3.5

4

0

5

10

15

20

25

30

ISOLATOR ON

I

(mA)

OUT

V (V)

I

Fig. 5: Transconductance characteristic

The CLT device is used between the connector and the opto-coupler of an I/O module. To secure the

coupler off state and the non-conduction of its diode, the maximum CLT output current is 40µA with R opto

= 15k

secure the opto-coupler on state.

The CLT limiter is insensitive to the output voltage up to 2.0V. Therefore, its output is able to drive any state

of the art opto-coupler. Some additional device can be added in series with the opto-coupler if the output

voltage remains within its functional limits.

A stand-alone sensor is normally connected on the CLT input. For a good off state control, its quiescent

current has to be less than 1.5 mA (EN60947-5-2 standard compatible) keeping then the opto-coupler off

(EN60947-5-2 standard compatible) corresponding to the difference between the minimum supply voltage

APPLICATION DESCRIPTION

The input and supply pins are designed to withstand electromagnetic interferences. As shown on the

device block diagram, each channel input is protected by a clamping diode that is connected to the

Ω, this clamping diode implements an

effective protection against transient voltage burst (±4 kV, IEC61000-4-4) and voltage surge (±1 kV,

IEC61000-4-5).

This combination allows the surge voltage to be applied from each input to other inputs, the ground and the

supply contacts in differential or common modes (see figure 6).

Ω and the conventional power supply protection that uses a

1000 V surge voltage (see figure 7).

Finally, an external output capacitor may be placed in parallel with the opto-coupler diode to filter the

transient disturbances injected in the inputs of the module and secure the immunity of the opto-coupler

itself.

SURGE VOLTAGE TEST CIRCUIT