STMicroelectronics L78M15CV-DG

Overview

L78M15CV-DG from STMicroelectronics is a three-terminal fixed-output positive linear voltage regulator delivering 15 V at up to 500 mA, featuring thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates with a 2 V dropout voltage, ±2 % output voltage tolerance (AB/AC grade), and supports junction temperatures from –40 °C to +125 °C in TO-220FP package - used for local regulation in industrial power supplies and embedded control modules.

For engineers reviewing the L78M15CV-DG datasheet, L78M15CV-DG pinout, L78M15CV-DG application, or L78M15CV-DG equivalent, key selection criteria include guaranteed 15 V output stability under load transients, integrated thermal shutdown behavior, SOA-protected pass transistor operation, and compatibility with standard 0.33 µF input / 0.1 µF output capacitor networks per ST's recommended layout.

Technical Context

This device implements a monolithic PNP pass transistor architecture with internal current limiting, thermal shutdown, and SOA compensation - enabling robust operation without external protection circuitry. Its feedback loop maintains regulation across line (VI = 17.5–30 V) and load (IO = 5–350 mA) variations while rejecting ripple up to 54 dB at 120 Hz.

The L78M15CV-DG uses a fixed internal reference and error amplifier to drive the pass element, with quiescent current held at 6 mA typical and drift of –1 mV/°C over temperature. Output noise is specified at 90 µV RMS (10 Hz–100 kHz), and it sustains short-circuit peak currents up to 700 mA before foldback activation.

Key Specifications

Pinout & Package

TO-220FP (Full Pack) package: vertical mounting, insulated tab, 3-pin through-hole configuration with integrated heat sink pad. Thermal resistance R_thJC = 5 °C/W enables 0.5 A continuous operation with minimal external heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7815CDT/NOPB and MC7815CD2TR4, the L78M15CV-DG offers superior thermal safety (SOA + hysteresis shutdown), lower noise, and tighter line/load regulation - making it optimal for mission-critical industrial and medical systems where reliability trumps marginal BOM cost savings.

Availability

L78M15CV-DG is available at Aetrix Electronics and suitable for industrial PLCs, automotive body electronics, medical infusion pumps, and test equipment requiring stable component supply with long-term lifecycle assurance.

Supply support for L78M15CV-DG 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 microcontrollers, power management ICs, and analog components for industrial, automotive, and consumer markets.

The L78M series belongs to ST's precision 500 mA linear regulator product line, engineered specifically for robust local regulation in space-constrained, thermally demanding applications where reliability under fault conditions is non-negotiable.

FAQ

What is the minimum input voltage required for stable 15 V output at 500 mA?

The L78M15CV-DG requires a minimum input voltage of 17 V to maintain regulation at 500 mA, based on its 2 V dropout specification. At lower loads (e.g., 350 mA), 16.5 V input is sufficient. Operation below the dropout threshold causes output voltage to track input minus pass transistor saturation drop, resulting in unregulated behavior.

Can this regulator be used without input or output capacitors?

While the L78M15CV-DG is internally compensated and does not require output capacitance for stability, ST strongly recommends a 0.33 µF input capacitor (tantalum or ceramic) placed directly across pins 1 and 2 to suppress high-frequency noise and prevent oscillation - especially when input traces exceed 5 cm. An output capacitor (0.1 µF ceramic) improves transient response but is not mandatory for basic regulation.

How does the thermal shutdown behave during repeated overloads?

The L78M15CV-DG features thermal shutdown with built-in hysteresis: it disables output when junction temperature exceeds ~165 °C and re-enables only after cooling by ~15 °C. This prevents latch-up during intermittent overloads (e.g., motor stall events), allowing automatic recovery without manual reset - a key advantage over older 78xx variants lacking hysteresis.

Is the TO-220FP package electrically insulated?

Yes - the TO-220FP (Full Pack) variant used in L78M15CV-DG has an electrically insulated metal tab, eliminating the need for insulating washers when mounting to a common heatsink. The insulation withstands ≥1500 V RMS, enabling safe use in grounded-chassis systems without risk of shorting the output to chassis ground via the heatsink.