Texas Instruments TL4242DRJR

Overview

TL4242DRJR from Texas Instruments is an adjustable constant-current LED driver IC capable of delivering up to 500 mA (±5%) with a typical reference voltage of 177 mV, low drop voltage of 0.35 V at 300 mA, and integrated PWM brightness control. It operates from 4.5 V to 42 V input supply and features open-load detection, overtemperature protection, and reverse-polarity proofing for high-reliability industrial LED lighting.

For engineers reviewing the TL4242DRJR datasheet, TL4242DRJR pinout, TL4242DRJR application, or TL4242DRJR equivalent, key selection criteria include output current adjustability via external R_REF, status output (ST) with configurable delay, thermal performance in WSON-8 package, and compatibility with microcontroller-based PWM dimming schemes.

Technical Context

The TL4242DRJR implements a precision current-regulation loop that maintains V_REF at 177 mV (typ) across an external shunt resistor to set output current (I_Q = V_REF/R_REF). Its high-impedance PWM input enables direct microcontroller interfacing without buffering and supports both active current regulation and low-power sleep mode based on VPWM logic levels.

Internally, it integrates a bandgap reference, error amplifier, pass transistor, open-collector ST output with delay timing controlled by capacitor on pin D, and comprehensive protection circuitry including overtemperature shutdown (T_J > 150°C), short-circuit proofing, and reverse-polarity tolerance up to –42 V on V_I.

Key Specifications

Pinout & Package

The TL4242DRJR is housed in an 8-pin WSON (DRJ) package measuring 4.00 mm × 4.00 mm with exposed thermal pad for enhanced heat dissipation. The thermal pad must be soldered directly to PCB and may be connected to ground or left floating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant-current LED driver applications.

Compared with AL8862SP-13 and LM3409HVMM/NOPB, the TL4242DRJR provides simpler, lower-noise linear regulation with integrated protection and status feedback in a compact WSON package-ideal for space-constrained, medium-current LED applications where input-to-output voltage differential is modest and EMI must be minimized.

Availability

TL4242DRJR is available at Aetrix Electronics and suitable for industrial signage, machine vision lighting, printer illumination, and automotive interior lighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for TL4242DRJR 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

Texas Instruments is a global semiconductor company designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and consumer markets.

The TL4242DRJR belongs to TI's high-voltage LED driver product line, engineered specifically for robust, thermally efficient constant-current regulation in harsh-environment lighting applications with integrated diagnostics and protection.

FAQ

What is the maximum output current capability of the TL4242DRJR?

The TL4242DRJR delivers up to 500 mA of adjustable constant current with ±5% accuracy over temperature and line variations. This is achieved by regulating the voltage across an external shunt resistor (R_REF) to a precise 177 mV reference. At R_REF = 0.39 Ω, the typical output current reaches 454 mA; at R_REF = 0.47 Ω, TL4242DRJR delivers 377 mA as verified in TI's typical application example. Current limit is internally clamped to 600 mA under short-circuit conditions.

How does the TL4242DRJR implement open-load detection?

The TL4242DRJR monitors the voltage at the REF pin to detect open-load faults. When LED current ceases, V_REF falls below 25 mV (typical lower threshold), causing the open-collector ST output to go low after a delay determined by the capacitor on pin D. For example, a 47 nF capacitor yields a 10 ms H→L delay, preventing nuisance tripping during brief transients. TL4242DRJR's ST output requires an external pullup resistor (≥4.7 kΩ) to function correctly.

Can the TL4242DRJR operate from a 3.3-V microcontroller PWM signal?

Yes, the TL4242DRJR accepts standard 3.3 V logic-level PWM signals directly. Its PWM input has high impedance (≤500 µA at 5 V) and defined thresholds: VPWM,H ≥ 2.6 V and VPWM,L ≤ 0.7 V. A 3.3 V GPIO output comfortably exceeds the high-threshold requirement and ensures reliable activation of the active mode. When PWM is low, TL4242DRJR enters sleep mode drawing only 0.1–2 µA, making it suitable for battery-backed systems.

What thermal considerations apply to the TL4242DRJR in continuous 500-mA operation?

In continuous 500 mA operation with 12 V input and 7 V LED string voltage, TL4242DRJR dissipates approximately ((12 − 7) × 0.5) + (12 × 0.022) ≈ 2.75 W. With R_θJA = 39.0°C/W and proper thermal pad soldering to a 2-layer PCB, this raises junction temperature by ~107°C above ambient. To maintain TJ ≤ 125°C, ambient must stay below 18°C-so derating or forced airflow is required at full load. TL4242DRJR's overtemperature protection shuts down output if TJ exceeds 150°C.

Is the TL4242DRJR pin-compatible with the automotive-grade TL4242-Q1?

Yes, the TL4242DRJR and TL4242-Q1 share identical DRJ (WSON-8) package dimensions, pinout, and electrical functionality. The TL4242-Q1 is AEC-Q100 qualified for automotive applications with extended temperature testing (–40°C to 125°C ambient) and enhanced process controls, while TL4242DRJR is rated for –40°C to 125°C and intended for industrial use. Both parts use the same T4242 marking and support identical R_REF-based current programming and ST/D/PWM interface behavior.