STMicroelectronics L78M24ACDT-TR

Overview

L78M24ACDT-TR from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 24 V at up to 500 mA output current, with ±2 % output voltage tolerance over 0 to 125 °C junction temperature range, thermal overload and short-circuit protection, and 2 V dropout voltage - used for local on-card DC power regulation in industrial control modules and embedded sensor interfaces.

For engineers reviewing the L78M24ACDT-TR datasheet, L78M24ACDT-TR pinout, L78M24ACDT-TR application, or L78M24ACDT-TR equivalent, key selection criteria include guaranteed extended-temperature operation (0–125 °C), DPAK package thermal resistance (R_thJA = 100 °C/W), load regulation ≤240 mV (IO = 5–200 mA), supply voltage rejection of 50 dB at 120 Hz, and 170 µV RMS output noise (10 Hz–100 kHz).

Technical Context

This device implements a monolithic silicon pass transistor with internal current limiting, thermal shutdown, and safe-area compensation to prevent destruction under overload or fault conditions. Its architecture relies on a bandgap reference and error amplifier driving the series pass element, with no external feedback required for fixed-output operation.

It operates with input voltages from 27 V to 38 V (VI ≥ VO + 2 V), supports stable regulation without mandatory input/output capacitors in low-noise, low-current applications, and exhibits −1.2 mV/°C output voltage drift over temperature at light load (IO = 5 mA).

Key Specifications

Pinout & Package

The L78M24ACDT-TR is housed in a surface-mount DPAK (TO-252) package with standard pinout: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. Thermal pad (exposed die attach area) must be soldered to PCB copper for effective heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78M24CDT and MC78M24BDTG, the L78M24ACDT-TR provides superior output accuracy and DPAK packaging for automated SMT production, while trading off cold-temperature operation - making it optimal for thermally stable industrial environments prioritizing voltage stability and board-level integration.

Availability

L78M24ACDT-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, embedded sensor signal conditioning, medical diagnostic equipment, and test & measurement instrumentation requiring stable component supply, long-lifecycle support, and DPAK-compatible manufacturing.

Supply support for L78M24ACDT-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 microcontrollers, power management ICs, analog chips, and discrete components for industrial, automotive, and consumer markets.

The L78MxxAC series belongs to ST's precision linear regulator product line, engineered specifically for industrial and embedded applications demanding high accuracy, robust protection, and extended-temperature reliability without external compensation.

FAQ

What is the minimum input voltage required for stable 24 V output?

The L78M24ACDT-TR requires a minimum input voltage of 26 V (VO + V_DROP = 24 V + 2 V) for stable regulation at room temperature. At maximum junction temperature (125 °C), dropout may increase slightly; design margin recommends VI ≥ 27 V across all operating conditions per datasheet Table 11.

Can this regulator be used without input or output capacitors?

Input and output capacitors are recommended but not strictly mandatory in low-current, low-noise applications. A 0.33 µF input capacitor is advised when connected via long traces to a filter, and a 0.1 µF output capacitor improves transient response. The device remains stable without them under light loads (<50 mA) and short interconnects.

How does thermal performance differ between DPAK and TO-220 packages?

In DPAK (L78M24ACDT-TR), R_thJA = 100 °C/W limits continuous output current to ~200 mA without PCB copper thermal relief; TO-220 (L78M24AC) achieves R_thJA = 50 °C/W, enabling >400 mA with minimal heatsinking. DPAK requires direct thermal pad soldering to inner-layer copper planes for effective heat transfer.

Is the L78M24ACDT-TR suitable for automotive applications?

No - the L78M24ACDT-TR is rated for 0 to 125 °C junction temperature and is not qualified to AEC-Q100. It lacks automotive-specific stress testing, qualification documentation, and guaranteed PPAP support. For automotive use, ST offers the L78M24AB variant (−40 to 125 °C) or dedicated automotive-grade regulators.