STMicroelectronics L78L24CD-TR

Overview

L78L24CD-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 24 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components, operates with ±8% output voltage tolerance (C grade), and is specified for 0–125 °C junction temperature range in SO-8 package. It serves as a robust local regulation solution in industrial power supplies and embedded control modules.

For engineers reviewing the L78L24CD-TR datasheet, L78L24CD-TR pinout, L78L24CD-TR application, or L78L24CD-TR equivalent, this device is selected for low-noise, self-protected 24 V rail generation where minimal BOM count, thermal resilience, and stable dropout behavior (1.7 V) are critical design requirements.

Technical Context

The L78L24CD-TR implements a monolithic series pass transistor with built-in thermal shutdown and foldback current limiting-no external compensation or feedback network required. Its SO-8 package integrates pins 2, 3, 6, and 7 electrically to the die attach flag, reducing thermal resistance (R_thJC = 20 °C/W) when mounted on ≥6 cm² copper pour.

It maintains regulation across input voltages from 27 V to 38 V (VI), delivers 24 V ±4% (min 22.8 V, max 25.2 V) under load (1–40 mA), and exhibits 200 µV_RMS output noise (10 Hz–100 kHz) and 31–37 dB supply voltage rejection at 120 Hz-key for analog sensor and microcontroller power domains.

Key Specifications

Pinout & Package

SO-8 package with exposed die attach flag connected internally to pins 2, 3, 6, and 7 for enhanced thermal performance. Standard SO-8 footprint (5.0 × 4.0 mm), RoHS-compliant ECOPACK2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output linear regulator applications.

Compared with LM78L24ACZ/NOPB and MC78L24CP, the L78L24CD-TR offers superior thermal management via SO-8 flag connection, tighter noise performance (200 µV vs. ≥300 µV), and higher PSRR-making it optimal for industrial and medical applications demanding reliability under thermal stress and EMI.

Availability

L78L24CD-TR is available at Aetrix Electronics and suitable for industrial automation, building control systems, and medical diagnostic equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for L78L24CD-TR 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, designing and manufacturing silicon solutions for automotive, industrial, and power management applications.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in space-constrained embedded systems where simplicity, protection, and thermal resilience outweigh programmability needs.

FAQ

What is the minimum input voltage required for regulation at full 100 mA load?

The L78L24CD-TR requires a minimum input voltage of 25.7 V to maintain 24 V output at 100 mA, based on its 1.7 V dropout specification. Below this, output voltage drops linearly with input; operation below 25.7 V is possible but results in unregulated output. Input must also stay within absolute maximum rating of 40 V for VO = 24 V.

Can the L78L24CD-TR be used in parallel to increase output current?

No-parallel operation is not recommended due to mismatch in output voltage (±8% tolerance) and lack of current-sharing circuitry. Uneven current distribution will cause one device to dominate and potentially overheat. For >100 mA, use an external pass transistor configured per Figure 14 in DS0424, or select a higher-current regulator like L7824CD.

Is the SO-8 package thermally compatible with standard reflow profiles?

Yes-the L78L24CD-TR SO-8 package is qualified for standard lead-free reflow (J-STD-020, peak 260 °C). The internal flag connection to pins 2/3/6/7 enhances thermal conduction during soldering and operation; ensure ≥6 cm² of 2-oz copper connected to those pins for optimal post-reflow thermal performance.

Does the device require input/output capacitors, and what values are validated?

Yes-ST specifies 0.33 µF ceramic (CI) on input and 0.1 µF ceramic (CO) on output for stability across all operating conditions. These values are validated in test circuits (Figure 3, DS0424) and prevent oscillation or poor transient response. Larger bulk capacitance (e.g., 10 µF tantalum) may be added in parallel but is not required for basic regulation.