STMicroelectronics L6221AD013TR

Overview

L6221AD013TR from STMicroelectronics is a monolithic quad Darlington switch IC with four non-inverting logic-controlled outputs, common enable input, and integral fast recirculation diodes. It supports up to 50 V output voltage, 1.8 A continuous per channel, TTL-compatible inputs, and low 1.6 V saturation voltage at 1.8 A - designed for driving inductive loads such as solenoids and relays in industrial control systems.

For engineers reviewing the L6221AD013TR datasheet, L6221AD013TR pinout, L6221AD013TR application, or L6221AD013TR equivalent, key selection criteria include output current capability per channel, clamp diode integration, thermal resistance (R_{th j-amb} = 80 °C/W), enable-controlled channel grouping, and SO16+2+2 package compatibility with high-density PCB layouts.

Technical Context

The L6221AD013TR implements four independent open-collector Darlington transistor stages sharing a common emitter node and dual clamp diode networks (CLAMP A/B). Each channel operates with TTL-level input thresholds (V_INL ≤ 0.8 V, V_INH ≥ 2.0 V) and enables synchronous on/off control via a single ENABLE signal.

Its internal architecture integrates fast freewheeling diodes rated for 1.8 A forward current (V_F = 2.0 V max) and supports paralleling of channels (e.g., IN1+IN4, IN2+IN3) to achieve up to 3 A load drive while maintaining matched switching timing and saturation characteristics.

Key Specifications

Pinout & Package

Package: SO16+2+2 (16-pin small outline integrated circuit with two additional exposed thermal pads).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad Darlington switch applications.

Compared with ULN2803A and TB6549FNG, the L6221AD013TR uniquely balances quad-channel density, 1.8 A per channel, integrated dual-clamp topology, and simple TTL/enable control - making it optimal for compact, high-reliability industrial I/O modules where discrete component count and inductive transient management are critical.

Availability

L6221AD013TR is available at Aetrix Electronics and suitable for industrial PLC output stages, relay interface modules, solenoid control subsystems, and automated test equipment requiring stable component supply and long-term obsolescence management.

Supply support for L6221AD013TR 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 automotive, industrial, and power discrete technologies with over 45 years of analog and power IC innovation.

The L6221AD013TR belongs to ST's high-voltage power driver product line, engineered specifically for robust, high-current switching in harsh industrial environments - emphasizing thermal resilience, inductive load handling, and system-level reliability without external protection components.

FAQ

What is the maximum junction temperature for continuous operation?

The L6221AD013TR has a specified operating junction temperature range of –40 °C to +150 °C. For reliable continuous operation at full 1.8 A per channel, thermal design must limit junction temperature to ≤150 °C using PCB copper area or external heatsinking, especially given its R_{th j-amb} of 80 °C/W in SO16+2+2 package.

Can CLAMP A and CLAMP B be connected to different voltage rails?

Yes - CLAMP A and CLAMP B are electrically isolated anodes for separate diode networks. They may be connected to different Zener voltages or supply rails to tailor flyback energy dissipation per output pair, as recommended in ST Application Note Figure 19 for mixed-load systems like dual-solenoid valves with differing inductance.

Is the ENABLE pin compatible with 3.3 V logic systems?

No - the ENABLE input requires TTL-compatible voltage levels: V_ENL ≤ 0.8 V (low) and V_ENH ≥ 2.0 V (high), but the device's VS supply must be 4.5–5.5 V. Direct 3.3 V enable signals may not guarantee reliable high-state recognition; a level shifter or pull-up to VS is required for 3.3 V controller interfacing.

How does channel paralleling affect thermal performance?

Paralleling channels (e.g., OUT1+OUT4) doubles current capacity but concentrates heat in adjacent pins. Thermal resistance remains unchanged per channel, so total power dissipation increases linearly. PCB layout must provide adequate copper area under both output pins and shared GND/CLAMP traces to avoid localized hot spots exceeding 150 °C junction temperature.