STMicroelectronics L78M08ABDT-1

Overview

L78M08ABDT-1 from STMicroelectronics is a fixed-output +8 V, 500 mA positive linear voltage regulator in DPAK package, featuring ±2 % output voltage tolerance at 25 °C, thermal overload protection, short-circuit current limiting, 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 L78M08ABDT-1 datasheet, L78M08ABDT-1 pinout, L78M08ABDT-1 application, or L78M08ABDT-1 equivalent, key selection criteria include dropout voltage (2 V), extended temperature operation (−40 to +125 °C), load regulation (80 mV over 5–200 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 built-in current limiting, thermal shutdown, and SOA compensation to prevent destruction under overload or fault conditions. Its architecture requires no external compensation and supports operation with minimal input/output capacitance (0.33 µF input, 0.1 µF output).

Designed for fixed-voltage local regulation, it maintains output stability across input voltages from 10.5 V to 25 V and load currents up to 500 mA. The AB grade guarantees full performance over −40 °C to +125 °C junction temperature, enabling use in automotive body control modules and industrial PLCs without derating.

Key Specifications

Pinout & Package

The L78M08ABDT-1 is housed in a surface-mount DPAK (TO-252) package with exposed drain pad for thermal conduction. Pin 1 is Input, Pin 2 is Ground, Pin 3 is Output - compatible with standard DPAK footprints per ST's recommended layout (A = 6.70 mm, B = 6.70 mm, E = 1.60 mm).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2931T-8.0/NOPB and MC78M08BDTRKG, the L78M08ABDT-1 provides superior output accuracy, guaranteed operation down to −40 °C, and DPAK packaging for automated assembly-making it optimal for industrial and automotive designs demanding reliability and repeatability.

Availability

L78M08ABDT-1 is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical sensor interfaces, and point-of-sale terminals requiring stable component supply with traceable sourcing and long-term lifecycle support.

Supply support for L78M08ABDT-1 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 deliver precision, ruggedized linear regulation for harsh-environment embedded systems-emphasizing thermal resilience, fault protection, and drop-in compatibility with legacy 78xx designs.

FAQ

What is the minimum input voltage required for stable 8 V output?

The L78M08ABDT-1 requires a minimum input voltage of 10.5 V to maintain regulation across its full load and temperature range. At 25 °C and 350 mA load, the dropout voltage is 2 V; however, design margin should account for worst-case conditions including −40 °C operation and 500 mA load, where dropout may increase slightly.

Can this regulator be used without input or output capacitors?

While the device can operate without external capacitors in low-current, low-noise environments, ST recommends a 0.33 µF input capacitor and 0.1 µF output capacitor for stable operation. These capacitors suppress high-frequency oscillation, improve transient response, and reduce output noise-especially critical when driving dynamic loads like relays or digital ICs.

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

The DPAK package has R_thJA = 100 °C/W versus TO-220's 50 °C/W, meaning the DPAK runs hotter at the same power dissipation. However, DPAK's exposed pad allows direct PCB copper pour connection, enabling effective heatsinking via thermal vias and internal layers-achieving comparable performance in space-constrained SMT designs when properly laid out.

Is the L78M08ABDT-1 qualified for automotive applications?

Yes-the AB grade is specified for −40 °C to +125 °C junction temperature and includes automotive-relevant protections: thermal shutdown, short-circuit current limiting, and SOA compensation. While not AEC-Q100 certified, its design and qualification testing align with common automotive subsystem requirements such as body control modules and infotainment power supplies.