STMicroelectronics CLT03-1SC3

Overview

CLT03-1SC3 from STMicroelectronics is a single-channel, self-powered digital input current limiter designed for factory automation I/O modules. It provides 4 mA typical input current limiting, ±2 kV IEC 61000-4-2 contact ESD protection, and operates across –30 °C to +125 °C ambient temperature. The device enables compliance with IEC 61131-2 Type 1 and Type 3 input characteristics without external power supply and supports both high-side and low-side configurations.

For engineers reviewing the CLT03-1SC3 datasheet, CLT03-1SC3 pinout, CLT03-1SC3 application, or CLT03-1SC3 equivalent, key selection criteria include its self-powered operation, integrated deglitch filter (2–5 µs propagation), fault mode activation at >30 V input, reverse-plugin compatibility, and SOT23-8L package suitability for space-constrained PLC input stages.

Technical Context

The CLT03-1SC3 implements a passive current-limiting U-I transfer function with defined ON/OFF thresholds (VTLH = 9.4–11 V, VTHL = 5–7.5 V) and 1.2–2.6 V hysteresis to meet IEC 61131-2 Type 1/Type 3 characteristic limits. Its internal deglitch filter uses a non-resettable monostable to suppress transients up to 35 kHz input frequency while maintaining <5 µs signal propagation.

Fault mode activates within 25 µs when VIN exceeds 30–40 V, reducing input current to 1–2.5 mA and disabling the output channel. The device draws zero quiescent current in OFF state and requires no external bias - energy is harvested directly from the input signal via internal charge pump and buffer capacitor (VBUF pin).

Key Specifications

Pinout & Package

SOT23-8L package (2.9 × 2.8 mm, 0.65 mm pitch), thermally optimized for surface-mount assembly in high-density I/O modules. Exposed pad not present; thermal path relies on PCB copper area per JEDEC JESD51-7.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital input current limiting applications.

Compared with CLT03-2Q3, the CLT03-1SC3 offers lower component cost and simpler layout for single-input nodes, while IL41080TR lacks critical safety features like fault mode and embedded diagnostics - making CLT03-1SC3 preferable for new IEC 61508-compliant designs.

Availability

CLT03-1SC3 is available at Aetrix Electronics and suitable for programmable logic controllers, remote I/O terminals, and industrial HMI systems requiring stable component supply, long-term lifecycle support, and compliance with IEC 61131-2 and IEC 61000-4-2 standards.

Supply support for CLT03-1SC3 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, delivering intelligent power, analog, MEMS, and microcontroller solutions for industrial, automotive, and consumer markets.

The CLT03 series belongs to ST's industrial interface portfolio, engineered specifically to simplify robust, self-powered digital input design in factory automation equipment while eliminating external biasing and discrete protection components.

FAQ

Does CLT03-1SC3 require an external power supply?

No. The CLT03-1SC3 is fully self-powered: it harvests energy from the input signal via the VBUF pin and internal charge pump. Zero current is drawn in the OFF state, and no external VCC or bias rail is needed - enabling true single-wire field-side interfacing.

How does the test pulse (TP) feature work, and what capacitor value should I use?

The TP pin accepts an external capacitor (100–4700 pF) between TP and OUTN to generate a periodic low-going test pulse on OUTP. Frequency ranges from 4.1 kHz (100 pF) to 219 kHz (4700 pF), with pulse width = 1/f_TP. To disable, short TP to OUTN. This enables automated safety diagnostics without external test circuitry.

Can CLT03-1SC3 drive both optocouplers and LVTTL inputs?

Yes. In isolated mode (INA/INB/OUTN used), it drives standard optocoupler LEDs. In non-isolated mode (INATT/PD used), the internal 2.85–4.25 kΩ pull-down enables direct 3.3 V LVTTL-compatible logic-level output - confirmed by VOUT(ON) = 3–3.6 V and IOUT = 1 mA in that configuration.

What happens during overvoltage conditions above 30 V?

When input voltage exceeds 30–40 V (VFAULT), the CLT03-1SC3 enters fault mode within 25 µs: input current drops to 1–2.5 mA, and the output is forced OFF. This prevents damage to downstream circuitry and satisfies safety-critical overvoltage protection requirements per IEC 61000-4-5 and functional safety standards.