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STMicroelectronics PCLT-2AT4
- Part No.:
- PCLT-2AT4
- Manufacturer:
- STMicroelectronics
- Category:
- Mixed Technology
- Package:
- 14-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
PCLT-2AT4.pdf
- Description:
- TVS DEVICE MIXED 14-TSSOP-EP
- Quantity:
- Payment:
- Shipping:
Inventory:4,251
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Product details
Overview
PCLT-2AT4 from STMicroelectronics is a dual-channel digital input termination IC for industrial 24 V DC automation systems. It implements IEC 61131-2 Type 2 (7.6 mA typical) or Type 3 (3.6 mA typical) current-limited logic inputs with overvoltage protection, programmable CMOS/opto-coupler output mode via VMOD pin, and integrated LED status indication. Used in PLC digital input modules to replace discrete resistor-diode networks.
For engineers reviewing the PCLT-2AT4 datasheet, PCLT-2AT4 pinout, PCLT-2AT4 application, or PCLT-2AT4 equivalent, this device supports robust sensor interface design requiring ESD (±15 kV air), surge (±500 V), burst (±4 kV), and reverse polarity (–30 V) immunity - critical for AS-Interface bus termination, proximity detector interfacing, and decentralized I/O modules.
Technical Context
The PCLT-2AT4 integrates two independent current-limiting channels, each with a precision reference-adjusted limiter (RREF = 10 kΩ or 22 kΩ), clamping diodes referenced to COM, and dual-mode output drivers. Its input voltage range spans –30 V to +35 V (with 750 Ω series resistor), enabling direct connection to 2- and 3-wire proximity sensors per EN 60947-5-2.
Each channel features temperature-compensated current limiting (<17% spread), low-threshold activation (2.3–2.6 V), and configurable output behavior: opto-coupler drive (≥1.5 mA) when VMOD < 0.75 V, or CMOS-compatible buffered output (80% VMOD high-level, 20% VMOD low-level) when VMOD > 2.9 V - supporting seamless integration with bus controllers or AS-Interface nodes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | –30 V to +35 V (with 750 Ω RI); enables reverse-polarity tolerance and surge resilience per IEC 61000-4-5 |
| Current Limit (RREF = 10 kΩ) | 6.1–8.8 mA; meets IEC 61131-2 Type 2 specification with ±17% tolerance and full-temp compensation |
| Current Limit (RREF = 22 kΩ) | 2.8–4.3 mA; satisfies IEC 61131-2 Type 3 requirement for low-power sensor interfaces |
| ESD Protection | ±15 kV air / ±8 kV contact (IEC 61000-4-2 Level 4); eliminates need for external TVS on input lines |
| Output Mode Selection | VMOD pin selects opto-coupler drive (VMOD < 0.75 V) or CMOS buffer (VMOD > 2.9 V); avoids external level-shifting circuitry |
| LED Drive Current | 4.4 mA typical (RREF = 10 kΩ); provides visible status indication without external current-setting components |
| Propagation Delay | 16 µs max TPLH; ensures reliable timing for 5 kHz digital input sampling in PLC scan cycles |
Pinout & Package
Package: TSSOP14 with exposed thermal pad (RTH(j-a) = 100 °C/W on 1.25 cm² copper), optimized for automated SMT assembly and thermal management in dense I/O modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN1, IN2 | Dual digital input terminals | Accept –30 V to +35 V sensor signals; internally clamped to COM; support 2-/3-wire proximity sensors |
| REF | Current reference programming node | Connects external RREF (10 kΩ or 22 kΩ) to set Type 2 or Type 3 input current limit |
| VC | Power supply input | 14–35 V operation; protected by internal clamping and RC network; withstands ±1 kV surge (IEC 61000-4-5) |
| COM | Common reference ground | Return path for clamping diodes, LED cathodes, and current limiter; must be connected to system ground |
| OUT1, OUT2 | Digital output drivers | Programmable as opto-coupler sink (≥1.5 mA) or CMOS buffer (80%/20% VMOD levels); no external pull-ups needed |
| MOD | Output mode selection | VMOD voltage configures output stage: low = opto mode, high = CMOS mode; decouples logic supply from sensor side |
| LED1, LED2 | Visual status outputs | Sink up to 4.4 mA (RREF = 10 kΩ); directly drives indicator LEDs without series resistors |
| COMP | Compensation reference | Internal bias node; connect to COM for stable current reference; not user-accessible in normal operation |
Key Features
| Feature | Design Value |
|---|---|
| IEC 61131-2 Type 1/2/3 compliance | Configurable via RREF and RI values - eliminates manual resistor selection for different sensor classes |
| Dual-mode output interface | Single-pin VMOD selection between opto-coupler drive and CMOS bus controller compatibility - reduces BOM count |
| Integrated LED status drive | 4.4 mA typical sink current at LED pins - enables direct LED connection without current-limiting resistors |
| Reverse polarity immunity | Withstands –30 V input bias indefinitely - protects against wiring errors and inductive kickback in solenoid monitoring |
| Thermal performance | TSSOP14 exposed pad achieves 100 °C/W junction-to-ambient - allows compact layout without heatsinks in I/O modules |
Applications
| AS-Interface Bus Termination | Proximity Sensor Interface |
|---|---|
Use Scenario: Unisolated connection of 2-wire AS-Interface field devices to a central controller without galvanic isolation. IC Role / Device Role / Timing Role: Dual-channel termination IC providing current-limited, surge-protected input conditioning and CMOS-level output signaling to the AS-i master. Use Value: Enables direct 24 V AS-Interface bus coupling with ±500 V surge immunity and 5 kHz signal bandwidth - eliminating external isolation transformers and reducing node cost. |
Use Scenario: Interfacing inductive proximity switches (PNP/NPN) to PLC digital input cards in harsh factory environments. IC Role / Device Role / Timing Role: Front-end current limiter and ESD-protected input stage that replaces discrete resistor-diode networks and opto-couplers. Use Value: Delivers IEC 61131-2 Type 2 compliance (7.6 mA) with ±15 kV ESD immunity and –30 V reverse polarity tolerance - increasing field reliability and reducing maintenance. |
| PLC Digital Input Module | Decentralized I/O Terminal |
Use Scenario: High-density digital input section in modular PLC backplanes where space, heat, and component count are constrained. IC Role / Device Role / Timing Role: Dual-channel termination IC performing input protection, current limiting, LED status, and logic-level translation in one package. Use Value: Reduces board area by >60% vs. discrete solutions and cuts power dissipation by 4× through precise current limiting - improving thermal margin in fanless enclosures. |
Use Scenario: Compact remote I/O blocks mounted near machinery for distributed sensor acquisition in automotive or packaging lines. IC Role / Device Role / Timing Role: Robust input conditioner handling mixed 2-/3-wire sensors with programmable current limits and visual status feedback. Use Value: Supports hot-swap-capable designs with fault-tolerant inputs (–30 V reverse, ±4 kV burst) and integrated LED indicators - minimizing downtime during field servicing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel industrial input termination applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IL420TR | Single-channel opto-coupler with integrated current limiter; no CMOS mode, no LED drive, no surge protection beyond basic ESD | Requires external surge protection and separate LED circuitry; limited to opto-isolated designs only | Choose only if galvanic isolation is mandatory and board space permits multiple discrete components per channel |
| MAX14827AUB+ | Dual-channel industrial digital input with 24 V sensing, but uses internal DAC-based current setting (no RREF); higher quiescent current (3.5 mA vs. 2 mA) | Lacks integrated LED drive and has lower ESD rating (±8 kV contact only); requires external voltage reference for precision | Select when programmable current via SPI is preferred over resistor-based configuration and isolation is not required |
Compared with IL420TR and MAX14827AUB+, the PCLT-2AT4 uniquely combines dual-channel current limiting, selectable output mode (opto/CMOS), integrated LED drive, and full IEC 61000-4 immunity in a single TSSOP14 package - delivering lowest component count and highest ruggedness for non-isolated industrial I/O.
Availability
PCLT-2AT4 is available at Aetrix Electronics and suitable for AS-Interface bus termination, proximity sensor interface, and PLC digital input module designs requiring stable component supply, long-term lifecycle support, and traceable sourcing for industrial automation deployments.
Supply support for PCLT-2AT4 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 specializing in industrial, automotive, and power management solutions, with deep expertise in rugged analog and mixed-signal ICs for factory automation.
The PCLT-2AT4 belongs to ST's industrial interface portfolio, designed specifically to simplify and harden digital input front-ends in PLCs, distributed I/O, and AS-Interface nodes - replacing legacy discrete protection networks with integrated, standards-compliant solutions.
FAQ
What is the function of the COMP pin on the PCLT-2AT4?
The COMP pin is an internal compensation node tied to the current reference circuitry. It is not intended for external connection and must remain unconnected in standard operation. Its internal bias ensures stable current limiting across temperature and supply variations - no external capacitor or resistor is required.
Can the PCLT-2AT4 drive a standard opto-coupler like PC817 directly?
Yes - in opto-coupler mode (VMOD < 0.75 V), OUT1/OUT2 deliver ≥1.5 mA sink current at 1.5 V output voltage, sufficient to forward-bias common opto-couplers such as PC817 (IF = 5 mA typ. for CTR > 100%). No external current-limiting resistor is needed when using the internal LED driver path.
How does the PCLT-2AT4 achieve IEC 61131-2 Type 2 and Type 3 compliance?
Type 2 (7.6 mA) and Type 3 (3.6 mA) compliance is achieved by selecting RREF = 10 kΩ or 22 kΩ respectively, combined with appropriate input resistors (RI = 750 Ω for Type 2, RI = 1.2 kΩ for Type 3). The device's tight current tolerance (<17%) and temperature compensation ensure consistent switching thresholds across –25°C to +85°C ambient.
Is the exposed pad on the TSSOP14 package electrically connected?
Yes - the exposed pad is internally connected to the COM pin and must be soldered to a PCB copper pour tied to system ground. This connection provides both thermal conduction (RTH(j-a) = 100 °C/W) and electrical reference for the clamping diodes and current limiter circuitry.
PCLT-2AT4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Package/Case:
- 14-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Series:
- PCLT
- Packaging:
- Tube
- Product Status:
- Active
- Voltage - Clamping:
- -
- Technology:
- Mixed Technology
- Number of Circuits:
- 2
- Applications:
- General Purpose
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-TSSOP-EP
PCLT-2AT4 FAQ
1.How can I place an order for PCLT-2AT4 through Aetrix?
Please submit a Request for Quotation (RFQ) for PCLT-2AT4 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 PCLT-2AT4 reliable?
The price and inventory of PCLT-2AT4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCLT-2AT4 is usually 5 days.
3.What payment methods are accepted for PCLT-2AT4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCLT-2AT4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCLT-2AT4?
PCLT-2AT4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCLT-2AT4 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 PCLT-2AT4?
For technical support, including PCLT-2AT4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCLT-2AT4 requirements.
6.How does Aetrix verify that PCLT-2AT4 is sourced from the original manufacturer or authorized distributors?
All PCLT-2AT4 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 PCLT-2AT4 meets industry standards.
7.What is the process for return or replacement of PCLT-2AT4?
All PCLT-2AT4 units undergo pre-shipment inspection (PSI). If there is an issue with PCLT-2AT4, 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 PCLT-2AT4 part is unused and in its original packaging.
Return procedure for PCLT-2AT4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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