Dual current limited overvoltage protected digital termination

The PCLT-2A is a dual input current limiter device designed for 24 V DC automation applications.

This product is compatible with the type 2 (7.5 mA) or type 3 (3 mA) characteristic of the IEC 61131-2 standard. An internal resistance RREFallows the limiting current value to be adjusted from 3 to 7.5 mA.

Each input voltage clamping block protects the module input against electromagnetic interference such as those described in the IEC 61131-2 standard, IEC 61000-4-2 (ESD), 4-4 (transient burst), 4-5 (voltage surge) and 4-6 (conducted radio frequency interference) standards. The supply input is also designed with such a protection structure.

The low tolerance of the current limitation allows a drastic reduction in the dissipation of the input compared to a resistive input. The PCLT2 is packaged in TSSOP14 - a very low RTHexposed pad package that allows the PCB cooling pad to be reduced.

The output block of each termination channel transfers the input logic state to a logic output and a light emitting diode (LED).

Key Features

  • 2 channel topology: low side input with common ground
  • Wide range input DC voltage:
    • VI = - 0.3 to 30 V with RI = 0 Ω
    • VI = - 30 to 35 V with RI = 750 Ω
  • Current limiter:
    • 3 to 7.5 mA programmable reference
    • ILIM = 6.1 mA to 8.8 mA with RREF = 10 kΩ
    • ILIM = 2.8 mA to 4.3 mA with RREF = 22 kΩ
    • Narrow limiter spread: < 17%
    • Temperature compensated operation
  • Output drive:
    • No output activation below 2 mA input
    • 1.5 mA minimum output activating current in opto-coupler mode
    • Programmable CMOS output mode option (VMOD > 2.9 V)
  • LED drive for sensor status: 4.4 mA typical with RREF = 10 kΩ
  • Input protection (RI = 750 Ω CIN = 22 nF)
  • IEC 61000-4-2 ESD, Level 4
    • In contact, ± 8 kV; in air, ± 15 kV
    • Criteria B: temporary disruption
  • IEC 61000-4-5 voltage surge, Level 3
    • ± 500 V with 42 Ω series resistor in differential mode
    • Criteria B: temporary disruption
  • IEC 61000-4-4 transient burst immunity
    • ± 4 kV peak voltage; 5 kHz repetitive rate
    • Criteria A: fully functional
  • IEC 61000-4-6 conducted RFI
    • 10 VRMS
    • Criteria A: fully functional
  • Input protection against -30 V reverse polarity
  • Ambient temperature: -25 to 85 °C
  • Benefits
    • Enable input to meet type1, 2 and 3 characteristics of IEC 61131-2 standard
    • Compatible operation with 2 and 3 wires proximity sensor according EN60947-5-2 standard
    • Flexible configuration driving either opto- coupler, or CMOS bus controller input, or 12 V AS-Interface network
    • Reduced overall dissipation
    • Enhanced functional reliability
    • Compact with high integration
    • Surface mount package for highly automated assembly
    • Insensitive to the on-state sensor impedance

Circuit Diagram

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Technical Documentation

Product Specifications
Description Version Size
Dual current limited overvoltage protected digital termination 2.0 601 KB
Application Notes
Description Version Size
PCLT (Programmable current limited termination) 1.2 859 KB
Technical Notes & Articles
Description Version Size
Packing information for IPAD™, protection, rectifiers, thyristors and AC Switches 5.0 1 MB

Publications and Collaterals

Description Version Size
Current-limiting terminations for automation digital inputs 2.1 400 KB
ST Protection Finder - The new app for Android and iOS 1.0 1 MB
Selection Guides
Description Version Size
Protection devices and integrated EMI filtering selection guide 2.0 743 KB
Description Version Size
Products and Solutions for Factory Automation and Control 2.0 3 MB

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Sample & Buy

Part Number Package Packing Type Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office  or our Distributors

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
PCLT-2AT4-TR ActiveHTSSOP14IndustrialEcopack2 0 0
PCLT-2AT4 ActiveHTSSOP14IndustrialEcopack2 0 0

(**) The Material Declaration forms available on st.com may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.