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CLT03-1SC3 | CLT03-2Q3 - Single & Dual-line self-powered digital input current limiters in SOT23-8L and QFN-16L

CLT03-1SC3 single line self powered digital input current limiter
CLT03-2Q3 self powered digital input current limiter

The self-powered CLT03-1SC3 and CLT03-2Q3 digital input current limiters drastically reduce power dissipation while improving EMC robustness in industrial automation and process control.

In high-density compact multi-channel modules, power consumption and associated heat dissipation is a critical consideration. An efficient current limitation should be applied in compliance with IEC 61131-2 specifications.

The CLT03-1SC3 and CLT03-2Q3 are industrial digital input current limiters that convert a 24 V digital input to 3 mA current to drive optical isolators or non-isolated LVTTL interfaces.

With a wide input voltage range up to 60 V, a built-in test pulse generator, and extra smart power limitation during overvoltage, the CLT03-1SC3 and CLT03-2Q3 simplify SIL certification for safety applications.

Key features of CLT03-1SC3 and CLT03-2Q3

vibration sensor with 10 year longevity
  • Accurate current limitation for Type 1 and Type 3 IEC 61131-2 digital inputs
  • Self-powered, eliminating the need for an external field-side power supply
  • 60 V maximum input voltage
  • Able to interface high side or low side sensors (sinking or sourcing inputs)
  • Over-voltage protected with extra power dissipation reduction above nominal operating conditions

Key benefits of CLT03-1SC3 and CLT03-2Q3

  • Flexibility: No need for an external field-side power supply!
  • Single- and dual-channel versions
  • Compatible with high/low-side sensors, opto-couplers and CMOS output
  • Safety: 60V tolerant, embedded configurable test pulses, channel isolation, indicator LED on process side
  • Space saving compared to discrete implementation
  • Reduced BOM costs

Application examples

industrial automation Process control & Industrial automation
programmable logic controller Programmable Logic Controllers (PLC)
motor control Motor control
  • CNC controls
  • Remote input modules
  • Current sourcing inputs
  • ...

How to test & prototype with CLT03 Series

Choose a development kit to start testing the capabilities and features of CLT03-1SC3 and CLT03-2Q3:

Isolated and non-isolated digital inputs on evaluation board


Isolated and non-isolated digital inputs on evaluation board based on CLT03-2Q3 self-powered current limited termination device.


Explore ST's complete TVS product portfolio and easily find the device that best fits your application using the parametric or series search engine. Available for Android™ and iOS™.

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Self-powered Digital Inputs with CLT03-2Q3

This presentation is presenting the CLT03-2Q3 and is summarizing the range of ST's self-powered digital input current limiters.

SELF-POWERED CURRENT LIMITERS - Design flexibility with single -and dual- line solutions

The CLT03 series of current limiters drastically reduces input losses while improving EMC robustness.

PDF current limiters self powered