CLT3-4B Datasheet, PDF (10/13 Pages) STMicroelectronics – Current limited over-voltage protected quad digital termination

Application information
CLT3-4B
Depending on the input type operation the input resistance R_I can be adjusted because of
the different on-state threshold V_{ON MIN}. So the surge voltage is also increased from the
minimum level of the type 3 to the type as shown in Table 6.
Table 6. Setting the input resistor R_I according to the input type operation
Type
V_{ON MIN} (V)
R_I (kΩ)
V_PP surge (kV)
1
15
2.2
2
3
11
1.2 to 1.8
1
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 12).
Thanks to its high resistance R_C = 4.7 kΩ, the supply pin V_C withstands IEC 61000-4-5 with
±1000 V surge voltage (see Figure 12).
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.
Figure 12. Input pin IN and supply pin V_C voltage surge test circuit
V_PPS = ±1 kV with 2 Ω
V_PPS
V_PPI
V_PPI
I
V_PP
V_PPI = ± 1 kV with 42 Ω
GND
PE/FE
5 nF
V_CC
R_C
R_I
R_I
R_I
V_C
IN₁
IN₂
CLT3 - 4
COM_P
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