STMicroelectronics L78M09ABDT-TR

Overview

L78M09ABDT-TR from STMicroelectronics is a fixed-output +9 V, 500 mA positive linear voltage regulator in DPAK (TO-252) package, featuring ±2 % output voltage tolerance, thermal overload protection, short-circuit protection, and safe operating area (SOA) protection. It delivers stable local regulation for microcontroller power rails, sensor interfaces, and industrial I/O modules requiring robust DC/DC conversion without external feedback components.

For engineers reviewing the L78M09ABDT-TR datasheet, L78M09ABDT-TR pinout, L78M09ABDT-TR application, or L78M09ABDT-TR equivalent, key selection criteria include dropout voltage (2 V), extended temperature range (–40 °C to +125 °C), quiescent current (6 mA), supply voltage rejection (56 dB at 120 Hz), and DPAK thermal resistance (R_thJA = 100 °C/W).

Technical Context

This three-terminal monolithic regulator uses an internal NPN pass transistor with integrated current limiting, thermal shutdown, and SOA compensation-enabling self-protecting operation under sustained overload or short-circuit conditions. Its architecture eliminates need for external compensation capacitors in most low-noise, low-current applications.

Designed for fixed-voltage use, it supports adjustable configurations via external resistors (e.g., current boosting or variable output), but requires minimum input-to-output differential of 2 V for regulation. Input voltage range is specified as 11.5 V to 24 V for nominal 9 V output, with absolute maximum input rating of 40 V.

Key Specifications

Pinout & Package

The L78M09ABDT-TR is housed in a surface-mount DPAK (TO-252) package with exposed thermal pad for enhanced heat dissipation. Pin 1 is Input, Pin 2 is Ground, Pin 3 is Output - standard configuration shared across L78MxxA series.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2940CT-9.0/NOPB, L78M09ABDT-TR offers tighter voltage accuracy and superior ripple rejection but requires higher headroom; versus MC78M09BDTG, it provides extended temperature capability and improved tolerance at modest cost premium.

Availability

L78M09ABDT-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical sensor interfaces, and smart energy meter subsystems requiring stable component supply across multi-year production cycles.

Supply support for L78M09ABDT-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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L78MxxA series belongs to ST's legacy linear regulator product line, engineered for ruggedness and ease-of-use in cost-sensitive, high-reliability embedded power applications where simplicity and proven protection features outweigh ultra-low IQ or ultra-low dropout requirements.

FAQ

What is the minimum input voltage required for regulation with L78M09ABDT-TR?

The minimum input voltage is 11.5 V under typical conditions (IO = 350 mA, TJ = 25 °C), based on its 2.0 V dropout voltage specification. At full 500 mA load and elevated temperature, design margin should increase this to ≥12.5 V to ensure regulation across process and temperature extremes.

Can L78M09ABDT-TR be used without input or output capacitors?

Input capacitance ≥0.33 µF is recommended for stability when wiring inductance exceeds ~10 nH (e.g., >5 cm traces); output capacitance ≥0.1 µF improves transient response. In low-current, short-trace applications, it may function without them-but ST specifies both in all test circuits and recommends their use for production designs.

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

DPAK (L78M09ABDT-TR) has R_thJA = 100 °C/W vs. TO-220's 50 °C/W. At 1 W dissipation, DPAK junction rise is ~100 °C above ambient versus ~50 °C for TO-220 - meaning DPAK requires more careful PCB copper area or heatsinking to achieve same reliability in high-power or high-ambient scenarios.

Is L78M09ABDT-TR compliant with modern environmental standards?

Yes - it is offered in ST's ECOPACK®-compliant DPAK package, meeting RoHS Directive 2011/65/EU and halogen-free requirements per IEC 61249-2-21. The "AB" suffix denotes industrial-grade temperature qualification (–40 °C to +125 °C), and the "-TR" indicates tape-and-reel packaging for automated assembly.