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Home > Products > Circuit Protection > Transient Voltage Suppressors (TVS) > Mixed Technology

STMicroelectronics CLT3-4BT6

Name: CLT3-4BT6
Brand: STMicroelectronics
SKU: CLT3-4BT6
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: CLT3-4BT6

Manufacturer:: STMicroelectronics

Category:: Mixed Technology

Package:: 20-TSSOP (0.173", 4.40mm Width)

Datasheet:: CLT3-4BT6.pdf

Description:: TVS DEVICE MIXED 20-TSSOP

Quantity:: RFQ Add To RFQ list

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Inventory:8,180

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Product details

Overview

CLT3-4BT6 from STMicroelectronics is a quad-channel current-limited, over-voltage protected digital termination IC for 24 V DC industrial I/O modules. It integrates input protection (IEC 61000-4-2/4-4/4-5), temperature-compensated 3 mA current limiting per channel, and opto-coupler drivers in a TSSOP20 package. Designed for PLC digital input front-ends, it supports EN60947-5-2-compliant 2-/3-wire proximity sensors and meets IEC 61131-2 Type 1 and Type 3 characteristics.

For engineers reviewing the CLT3-4BT6 datasheet, CLT3-4BT6 pinout, CLT3-4BT6 application, or CLT3-4BT6 equivalent, this device delivers validated ESD immunity (±8 kV air, ±6 kV contact), precise 3.4–5 V activation threshold, low 40 µA off-state output current, robust reverse polarity tolerance (−30 V), and thermal resistance of 90 °C/W - all critical for reliable industrial fieldbus node design.

Technical Context

The CLT3-4BT6 implements four independent termination channels, each combining an input clamping diode, series current limiter with 0.25×/0.75×/1.5 mA trip points, and a dedicated opto-coupler driver stage. Its biasing circuit maintains stable VC supply at 10 V with 550–800 µA quiescent current, while internal compensation ensures ±2% current limit stability across −25 to +85 °C ambient.

All inputs share a common COM pad (pins 1,3,6,8,10,11,13,15,16,18,20) optimized for thermal dissipation and EMI suppression. The device operates with RI = 1.2 kΩ for Type 3 (V_ON-MIN = 11 V) or RI = 1.8 kΩ for enhanced reverse-polarity robustness, enabling differential-mode surge immunity up to ±1 kV per IEC 61000-4-5.

Key Specifications

Parameter	Value and Actual Design Meaning
Input voltage range	−0.3 to 30 V (RI = 0 kΩ); −30 to 30 V (RI = 1.8 kΩ) - enables reverse-polarity fault tolerance and wide-field sensor compatibility
Current limit per channel	3 mA typ (2.1–3.7 mA) - reduces power dissipation vs. resistive termination and eliminates need for external current-setting resistors
Activation threshold	3.4–5 V (at I_IN = 2.1 mA) - ensures reliable turn-on for standard 24 V industrial sensors while rejecting noise below 3.4 V
ESD protection	±8 kV air / ±6 kV contact (IEC 61000-4-2) - meets Class 3 requirements without external TVS diodes
Output drive capability	1.5–2 mA on-state; ≤40 µA off-state - directly drives standard opto-couplers (e.g., PC817, LTV-817) without buffer stages
Thermal resistance	90 °C/W (j-a, 2 cm² copper) - supports high-density PCB layouts with minimal heatsinking
Propagation delay	6 µs (t_PLH), 10 µs (t_PHL) - supports 5 kHz fieldbus cycle rates with deterministic timing

Pinout & Package

CLT3-4BT6 is housed in a 20-pin TSSOP package (6.5 mm × 6.4 mm × 1.05 mm) with exposed thermal pad (COM) for enhanced heat dissipation. All COM pins (1,3,6,8,10,11,13,15,16,18,20) must be externally shorted to a single large copper area to achieve rated thermal performance.

Pin	Circuit Role	Design Meaning
1,3,6,8,10,11,13,15,16,18,20 (COM)	Common ground / thermal pad	Shared reference for all channels; enlarged copper area lowers thermal resistance and suppresses EMI coupling
2,4,5,7,9,12,14,17,19 (IN1–IN4, ESD12, ESD34, ESDC)	Input terminals with integrated clamping	Four isolated input channels (IN1–IN4); ESD12/ESD34 protect pairs; ESDC protects supply - enable multi-point surge injection testing
11,13,16,19 (OUT1–OUT4)	Opto-coupler driver outputs	Open-collector outputs sinking 1.5–2 mA when active; <40 µA leakage when inactive - directly interface LED anodes of isolation optos
12 (VC)	Bias supply input	Internal 10 V regulator input; accepts 19–30 V supply; RC = 4.7 kΩ enables ±1 kV surge immunity per IEC 61000-4-5

Key Features

Feature	Design Value
Quad-channel integration	Replaces four discrete termination circuits (resistor + Zener + opto-driver), reducing BOM count by ≥12 components per channel
Temperature-compensated current limit	Maintains ±2% accuracy from −25 to +85 °C - eliminates thermal drift-induced false triggers in uncontrolled environments
Type 1 & Type 3 IEC 61131-2 compliance	Configurable via RI (1.2 kΩ or 1.8 kΩ) - supports both 12.34 V (Type 1) and 11 V (Type 3) on-thresholds without hardware change
Reverse polarity resilience	Withstands −30 V input with ≤16.2 mA reverse current (RI = 1.8 kΩ) - prevents latch-up during solenoid demagnetization events
EMC-hardened layout	Dedicated ESD pins (ESD12/ESD34/ESDC) and COM routing minimize loop area - achieves Level A burst immunity (±4 kV) without external filtering

Applications

PLC Digital Input Module

Industrial Fieldbus Node

Use Scenario: Front-end termination for 24 V DC digital inputs in modular PLC chassis with hot-swap capability.

IC Role / Device Role / Timing Role: Quad-channel signal conditioner that converts raw sensor voltage into isolated logic-level signals for microcontroller GPIOs.

Use Value: Eliminates need for four separate 1.2 kΩ/1 W resistors and discrete TVS diodes - reduces board area by 35% and improves MTBF by removing 16 passive failure points.

Use Scenario: Input conditioning for PROFIBUS DP or CANopen slave nodes in factory automation cabinets.

IC Role / Device Role / Timing Role: Provides galvanically isolated, EMC-hardened input interface between field wiring and communication controller UART/I²C peripherals.

Use Value: Meets IEC 61000-4-4 Level A (±4 kV burst) and IEC 61000-4-5 Level B (±1 kV surge) without external filters - cuts EMC debug time by >60%.

Machine Tool I/O Terminal Block

2-/3-Wire Proximity Sensor Interface

Use Scenario: DIN-rail mounted I/O terminal block accepting mixed 2-wire NAMUR and 3-wire PNP sensors in CNC machine control panels.

IC Role / Device Role / Timing Role: Universal termination unit supporting both sink and source sensor topologies via shared COM architecture.

Use Value: Single-footprint support for EN60947-5-2 compliant sensors with <1.5 mA off-state leakage - prevents spurious triggering from capacitive coupling in high-noise motor environments.

Use Scenario: Direct interface to inductive proximity switches (e.g., Pepperl+Fuchs NBB series) in packaging line controllers.

IC Role / Device Role / Timing Role: Current-limiting front-end that enforces 3 mA max input current while driving opto-isolators for microcontroller safety isolation.

Use Value: Enables use of low-cost 15 kΩ opto-LEDs (e.g., LTV-817) with guaranteed 1.5 mA turn-on current - reduces opto-coupler BOM cost by 40% vs. high-current alternatives.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TI ISO1211	Single-channel, integrated 2.5 kV_RMS isolation; no built-in current limiting - requires external resistor	Targeted at isolated analog sensing; lacks IEC 61131-2 Type 1/3 configuration and multi-channel density	Select for systems requiring reinforced isolation but accepting higher component count and reduced channel density
Infineon IL610	Quad-channel, 3.5 mA current limit; no integrated ESD protection - needs external ±8 kV TVS per input	Designed for automotive body control; lacks IEC 61000-4-5 surge rating and industrial thermal derating	Select only if operating in controlled environments with added external protection and thermal margin analysis

Compared with CLT3-4BT6, ISO1211 trades channel integration and embedded protection for higher isolation rating, while IL610 offers similar quad topology but demands external ESD components and lacks industrial-grade surge immunity - making CLT3-4BT6 the only solution delivering full IEC 61131-2/61000-4-x compliance in a single TSSOP20 package.

Availability

CLT3-4BT6 is available at Aetrix Electronics and suitable for industrial automation, programmable logic controller (PLC) input modules, and fieldbus node designs requiring stable component supply, long-term lifecycle support, and traceable sourcing for safety-critical deployments.

Supply support for CLT3-4BT6 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, specializing in industrial, automotive, and power management solutions with over 40 years of analog/mixed-signal IC expertise.

The CLT3-4BT6 belongs to ST's industrial interface portfolio, engineered specifically for ruggedized digital input conditioning in PLCs, DCS, and I/O modules - prioritizing EMC resilience, thermal reliability, and standards compliance over consumer-grade cost optimization.

FAQ

What is the maximum allowable reverse input voltage for CLT3-4BT6?

The CLT3-4BT6 withstands −30 V reverse input voltage when configured with RI = 1.8 kΩ, limiting reverse current to 16.2 mA per channel. This is validated per Figure 10 in the datasheet and supports safe operation during inductive load demagnetization events without damage or latch-up.

Can CLT3-4BT6 drive opto-couplers with forward voltage > 1.5 V?

Yes - the CLT3-4BT6 output stage delivers ≥1.5 mA into opto-coupler LEDs with R_LED(0 V) = 15 kΩ, supporting forward voltages up to 2.0 V. Its output remains functional even when V_OUT rises to 2.5 V, ensuring compatibility with standard PC817, LTV-817, and TLP290 series devices.

How does the CLT3-4BT6 meet IEC 61131-2 Type 3 requirements?

By setting RI = 1.2 kΩ, the CLT3-4BT6 achieves V_ON-MIN = 11 V and V_OFF-MAX = 1.5 V, satisfying Type 3 thresholds. Its 3 mA current limit and 3.4–5 V activation window ensure clean switching margins across −25 to +85 °C, verified in Table 3 and Figure 4 of the datasheet.

Is external output capacitance required for EMC compliance?

No - the CLT3-4BT6 achieves IEC 61000-4-4 Level A immunity (±4 kV burst) without external capacitors. However, adding 22 nF across OUTx–COM (per Figure 9) further improves transient rejection in ultra-noisy environments like welding cells or VFD installations.

CLT3-4BT6 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Package/Case:: 20-TSSOP (0.173", 4.40mm Width)

Series:: CLT

Packaging:: Tube

Product Status:: Last Time Buy

Voltage - Clamping:: -

Technology:: Mixed Technology

Number of Circuits:: 4

Applications:: General Purpose

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-TSSOP

CLT3-4BT6 FAQ

1.How can I place an order for CLT3-4BT6 through Aetrix?

Please submit a Request for Quotation (RFQ) for CLT3-4BT6 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for CLT3-4BT6 reliable?

The price and inventory of CLT3-4BT6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CLT3-4BT6 is usually 5 days.

3.What payment methods are accepted for CLT3-4BT6?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CLT3-4BT6 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for CLT3-4BT6?

CLT3-4BT6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your CLT3-4BT6 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for CLT3-4BT6?

For technical support, including CLT3-4BT6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CLT3-4BT6 requirements.

6.How does Aetrix verify that CLT3-4BT6 is sourced from the original manufacturer or authorized distributors?

All CLT3-4BT6 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that CLT3-4BT6 meets industry standards.

7.What is the process for return or replacement of CLT3-4BT6?

All CLT3-4BT6 units undergo pre-shipment inspection (PSI). If there is an issue with CLT3-4BT6, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The CLT3-4BT6 part is unused and in its original packaging.

Return procedure for CLT3-4BT6:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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