STMicroelectronics L78M05CV

Overview

L78M05CV from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 5 V ±2 % output at up to 0.5 A, featuring thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates across an input voltage range of 7–25 V and is commonly used for local on-card regulation in industrial control modules, sensor signal conditioning circuits, and embedded microcontroller power rails.

For engineers reviewing the L78M05CV datasheet, L78M05CV pinout, L78M05CV application, or L78M05CV equivalent, key selection criteria include guaranteed 5 V output tolerance (±2 %), junction temperature range of 0 to 125 °C, dropout voltage of 2 V at 25 °C, 62 dB supply voltage rejection at 120 Hz, and compatibility with TO-220FP package mounting and heat sinking.

Technical Context

The L78M05CV implements a monolithic bipolar pass transistor architecture with internal current limiting, thermal shutdown, and SOA compensation-ensuring robust operation under sustained overload or transient fault conditions. Its feedback loop maintains stable 5 V output without external components, and its quiescent current remains tightly controlled at 6 mA typical with ≤0.8 mA variation over load and input voltage ranges.

Designed for fixed-output use, it supports extended functionality via external circuitry: adjustable output voltage configurations (e.g., using resistive dividers), constant-current sources, high-current boost stages, and tracking regulators-all validated in ST's DS0425 application circuits. No output capacitor is required for stability, though 0.1 µF improves transient response.

Key Specifications

Pinout & Package

Supplied in TO-220FP (Full Pack) package: insulated case, vertical mounting, 3-pin through-hole format with integrated heatsink tab. Thermal resistance junction-to-case is 5 °C/W, enabling >0.5 A continuous output with minimal heatsinking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78M05CDT, L78M05CV offers identical accuracy but superior thermal resistance in TO-220FP (5 vs. 60 °C/W junction-to-ambient), while MC78M05BDTG trades tolerance and drift for lower unit cost-making L78M05CV optimal for thermally constrained, accuracy-critical 5 V local regulation.

Availability

L78M05CV is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical sensor signal chains, and smart energy meter MCU subsystems requiring stable component supply across multi-year production cycles.

Supply support for L78M05CV 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The L78M series belongs to ST's precision 500 mA linear regulator product line, engineered for robust local regulation in harsh environments-emphasizing thermal resilience, built-in fault protection, and compatibility with legacy through-hole and modern insulated-packaging standards.

FAQ

What is the minimum input voltage required for stable 5 V output from L78M05CV?

The minimum input voltage is 7 V under all operating conditions, based on its 2 V dropout voltage specification at 25 °C and full 500 mA load. At elevated junction temperatures or higher loads, the dropout may increase slightly; design margin recommends maintaining VI ≥ 7.5 V for guaranteed regulation across the full 0–125 °C range.

Can L78M05CV be used without input or output capacitors?

Yes-L78M05CV is internally compensated and does not require an output capacitor for stability. However, a 0.33 µF input capacitor is strongly recommended if the regulator is located more than 10 cm from the main filter capacitor, and a 0.1 µF output capacitor improves transient response to step-load changes. These values are specified in ST's DS0425 application guidance.

How does thermal protection operate in L78M05CV during overload?

Thermal protection activates when junction temperature exceeds approximately 150 °C, disabling the pass transistor until temperature falls below ~135 °C (with hysteresis). This shutdown is fully automatic and repeatable-no latch-up occurs. The TO-220FP package's 5 °C/W junction-to-case resistance allows >0.5 A continuous output with modest heatsinking, per ST's thermal data tables.

Is L78M05CV compatible with lead-free reflow soldering processes?

Yes-L78M05CV in TO-220FP packaging is qualified for lead-free reflow per JEDEC J-STD-020, with peak reflow temperature up to 260 °C. ST specifies it as ECOPACK2-compliant, meaning it meets RoHS, REACH, and halogen-free requirements. The insulated case eliminates need for isolation slots in PCB layout during wave soldering.