STMicroelectronics L78M05ABV

Overview

L78M05ABV from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 5 V ±2 % output at up to 500 mA, featuring thermal overload protection, short-circuit protection, and safe operating area (SOA) compensation. It operates across –40 °C to +125 °C and is used for local on-card regulation in industrial power supplies, embedded controllers, and sensor interface modules.

For engineers reviewing the L78M05ABV datasheet, L78M05ABV pinout, L78M05ABV application, or L78M05ABV equivalent, key selection criteria include guaranteed ±2 % output tolerance over temperature, 2 V dropout voltage at 25 °C, internal current limiting, and DPAK package thermal resistance of 8 °C/W junction-to-case - critical for thermally constrained PCB layouts.

Technical Context

The L78M05ABV implements a monolithic pass transistor with integrated bandgap reference, error amplifier, and protection circuitry. Its SOA protection dynamically reduces short-circuit current as pass transistor V_CE increases, preventing second breakdown during fault conditions.

It requires no external components for basic operation but recommends a 0.33 µF input bypass capacitor and 0.1 µF output capacitor for stability under transient load conditions. Input voltage range is 7–25 V for 5 V output, with supply voltage rejection of 62 dB at 120 Hz.

Key Specifications

Pinout & Package

Supplied in surface-mount DPAK (TO-252) package with exposed thermal pad for enhanced heat dissipation; R_thJC = 8 °C/W enables >350 mA continuous operation with minimal copper area.

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 L78M05ABV provides tighter ±2 % output accuracy and guaranteed operation down to –40 °C - making it the only choice for industrial-grade analog signal chains and long-lifetime embedded systems requiring minimal calibration drift.

Availability

L78M05ABV is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical instrumentation requiring stable component supply and long-term lifecycle support.

Supply support for L78M05ABV 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 designing and manufacturing silicon solutions for automotive, industrial, and consumer markets, with core expertise in analog, power, and microcontroller technologies.

The L78MxxA series was developed specifically for robust local regulation in harsh industrial environments - emphasizing thermal resilience, wide temperature operation, and intrinsic fault protection without external components.

FAQ

What is the minimum input voltage required for stable 5 V output?

The L78M05ABV requires a minimum input voltage of 7 V to maintain regulation under full 500 mA load, based on its 2 V dropout voltage specification at 25 °C. At elevated temperatures or maximum load, design margin should increase input to ≥7.5 V to ensure stability across process and temperature variation.

Can this regulator be used without input or output capacitors?

No - ST specifies a 0.33 µF input capacitor (tantalum, mylar, or low-ESR ceramic) and 0.1 µF output capacitor for stable operation. Omitting either risks oscillation or poor transient response, especially with long input traces or large capacitive loads, as confirmed in Section 7.1 of the datasheet.

How does the SOA protection function during a short-circuit event?

SOA protection reduces short-circuit current as the pass transistor's collector-emitter voltage rises - for example, limiting peak current to ~700 mA at low V_CE, but dropping to ~300 mA at higher V_CE. This prevents second breakdown by keeping instantaneous power within safe limits, as shown in Figure 9 and described in Section 7.1.

Is the DPAK package thermally compatible with standard TO-252 footprints?

Yes - ST confirms full mechanical compatibility between its STD-ST DPAK and subcontractor variants (Fujitsu, IDS), including identical footprint dimensions (A = 2.20–2.40 mm, D = 6.00–6.20 mm, E = 6.40–6.60 mm). The recommended land pattern in Figure 24 applies universally across all L78M05ABV DPAK variants.