PCLT-2A

The PCLT-2A is a dual input 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. Available in a two channels configuration, PCLT-2A offers a high-density termination by minimizing the conducting dissipation and the external components count. PCLT-2A is housed in a surface mount package to reduce the printed board size. Made of an input voltage protection, a serial current limiting circuit and an output interface, each channel circuit terminates the connection between the logic input and its associated high side sensor or switch.

The PCLT-2A is a current limited dual channel circuit compatible with the type 2 (7.5 mA) or type 3 (3 mA) characteristic of the IEC61131-2 standard. An external resistance RREF allows the limiting current value to be adjusted from 3 to 7.5 mA.

The unique structure of the PCLT-2A limiter allows its activation threshold to be low and insensitive to the output voltage up to 2.5 V. Each input voltage of PCLT-2A 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) and 4-6 (conducted radio frequency interferences) standards. The supply input of PCLT-2A is also designed with such a protection structure.

The current limiting circuit of PCLT-2A 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. Furthermore, the PCLT-2A is housed into a very low RTH exposed pad TSSOP14 package that allows the PCB cooling pad to be reduced: the overall module becomes smaller and the hot spot effect is reduced. The output block of each termination channel transfers the input logic state to a logic output and a Light Emitting Diode (LED) that allows this state to be checked visually.