STMicroelectronics L78M15ABDT-TR

Overview

L78M15ABDT-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a precise +15 V output at up to 500 mA, featuring ±2 % output voltage tolerance, thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates across –40 °C to +125 °C and is used in industrial control power rails, embedded microcontroller supply domains, and analog sensor biasing circuits requiring stable mid-range DC voltage.

For engineers reviewing the L78M15ABDT-TR datasheet, L78M15ABDT-TR pinout, L78M15ABDT-TR application, or L78M15ABDT-TR equivalent, key selection criteria include dropout voltage (2 V), load regulation (≤300 mV over 5–500 mA), supply voltage rejection (54 dB at 120 Hz), junction temperature range (–40 to +125 °C), and DPAK package thermal resistance (R_thJA = 100 °C/W).

Technical Context

This fixed-output linear regulator uses an internal NPN pass transistor with integrated current limiting, thermal shutdown, and SOA compensation-ensuring robustness under sustained overload or transient fault conditions. Its architecture eliminates external feedback components, relying on trimmed internal resistors for output accuracy.

Designed for local on-card regulation, it replaces centralized supplies to reduce noise coupling and distribution losses. Input voltage range is 17.5 V to 30 V for nominal 15 V output, with absolute maximum input rating of 40 V for VO ≥ 20 V.

Key Specifications

Pinout & Package

The L78M15ABDT-TR is housed in a surface-mount DPAK (TO-252) package with exposed thermal pad for enhanced heat dissipation. R_thJA = 100 °C/W enables 500 mA operation with minimal PCB copper area when ambient ≤60 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78M15CDT-TR and MC78M15BDTG, the L78M15ABDT-TR offers tighter ±2 % regulation and guaranteed –40 °C startup - making it the sole choice for precision industrial and automotive applications where output stability across extreme ambient conditions is mandatory.

Availability

L78M15ABDT-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical diagnostic instrumentation, and test & measurement equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for L78M15ABDT-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 consumer markets since 1987.

The L78MxxA series was developed to replace legacy 78xx regulators with improved thermal robustness, extended temperature range, and tighter output tolerance - specifically targeting industrial control, instrumentation, and automotive subsystems demanding reliability without design complexity.

FAQ

What is the minimum input voltage required for regulation at full 500 mA load?

The L78M15ABDT-TR requires a minimum input voltage of 17.5 V to maintain +15 V output at 350 mA (per datasheet test condition), and 17.5 V remains valid for full 500 mA operation given its 2 V dropout voltage. Below this, output voltage collapses linearly with decreasing VI–VO differential.

Can this regulator be used in adjustable configurations?

Yes - the L78M15ABDT-TR can be configured as an adjustable regulator using external resistors per Figure 18 in the datasheet, enabling output voltages from 7.0 V to 20 V. However, the internal 15 V reference is bypassed, so accuracy depends on external resistor tolerance and temperature drift.

Is a heat sink required for 500 mA continuous operation?

A dedicated heat sink is not required if PCB copper area provides sufficient thermal conduction. With R_thJA = 100 °C/W and 2 V dropout at 500 mA (1 W dissipation), junction temperature rise is ~100 °C above ambient. At 25 °C ambient, T_J reaches 125 °C - the maximum rated value - so ≥2 cm² of 2-oz copper pour is recommended for reliability.

Does this part support reverse-voltage protection?

No - the L78M15ABDT-TR lacks built-in reverse-polarity protection. Applying negative voltage to the input pin relative to ground may cause destructive latch-up. An external series diode (e.g., 1N5819) is required if reverse input is possible in the system.