STMicroelectronics L78M05ACDT-TR

Overview

L78M05ACDT-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a precise 5 V ±2 % output at up to 500 mA, featuring thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates over an extended junction temperature range of 0 °C to 125 °C and requires only 2 V dropout voltage, making it suitable for local on-card regulation in industrial control modules, embedded power supplies, and sensor interface circuits.

For engineers reviewing the L78M05ACDT-TR datasheet, L78M05ACDT-TR pinout, L78M05ACDT-TR application, or L78M05ACDT-TR equivalent, key selection considerations include guaranteed output voltage tolerance, thermal shutdown behavior, DPAK package thermal resistance (R_thJA = 100 °C/W), and compatibility with standard 0.33 µF input / 0.1 µF output capacitor configurations.

Technical Context

This device implements a monolithic series pass transistor architecture with internal current limiting, thermal shutdown, and SOA compensation-ensuring robust operation under sustained overload or short-circuit conditions. Its fixed 5 V output is trimmed during manufacturing to ±2 % tolerance at 25 °C and maintains stability across load (5–500 mA) and line (7–20 V input) variations.

The L78M05ACDT-TR uses a DPAK (TO-252) surface-mount package with three terminals: input, output, and ground. It achieves 62 dB supply voltage rejection at 120 Hz and delivers low 40 µV_RMS output noise (10 Hz–100 kHz), supporting noise-sensitive analog subsystems without requiring external filtering.

Key Specifications

Pinout & Package

The L78M05ACDT-TR is housed in a DPAK (TO-252-3) surface-mount package with exposed thermal pad for enhanced heat dissipation. Package dimensions comply with ST's STD-ST mechanical specification (A = 2.20–2.40 mm, D = 6.00–6.20 mm, E = 6.40–6.60 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78M05CDT-TR and MC78M05BDTG, the L78M05ACDT-TR offers tighter output tolerance, superior thermal protection architecture, and lower noise-making it the preferred choice for industrial and medical applications demanding reliability and precision.

Availability

L78M05ACDT-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, medical patient monitor front-ends, and point-of-sale terminal power management requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for L78M05ACDT-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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L78MxxAC series belongs to ST's precision linear regulator product line, engineered specifically for industrial and medical applications requiring guaranteed output accuracy, extended temperature operation, and integrated fault protection without external components.

FAQ

What is the maximum input voltage for L78M05ACDT-TR?

The absolute maximum DC input voltage is 35 V for VO = 5 V. Operation above 20 V input is not recommended for continuous use due to thermal constraints-power dissipation rises sharply as (V_IN – 5 V) × I_O increases, and the DPAK package's R_thJA of 100 °C/W limits practical input to ≤12 V at full 500 mA load without heatsinking.

Does L78M05ACDT-TR require input and output capacitors?

Yes: a minimum 0.33 µF input capacitor (tantalum or ceramic) is required for stability, especially with long input traces; a 0.1 µF ceramic output capacitor is mandatory to suppress high-frequency noise and ensure transient response. Larger values (e.g., 10 µF tantalum + 0.1 µF ceramic) improve ripple rejection but do not replace the specified minimums.

How does thermal shutdown behave during overload?

When junction temperature exceeds ~150 °C, the internal thermal limiter disables the pass transistor, dropping output voltage to near zero. Once T_J falls below ~130 °C (hysteresis), regulation automatically resumes. This cycle repeats during sustained overload-no latch-up or manual reset is needed, and the device remains undamaged.

Can L78M05ACDT-TR be used in adjustable configurations?

Yes-by adding two external resistors to the ground pin, it can generate adjustable outputs from 7.0 V to 20 V (per Figure 18 in ST Doc ID 2147). However, output accuracy degrades due to resistor tolerance and reference drift; the fixed 5 V configuration remains the only one guaranteed to ±2 % across temperature and load.