STMicroelectronics L78M08CV-DG

Overview

L78M08CV-DG from STMicroelectronics is a three-terminal positive fixed-output linear voltage regulator delivering 8 V at up to 500 mA, featuring thermal overload protection, short-circuit current limiting, and safe operating area (SOA) protection. It operates with input voltages up to 35 V (for VO = 8 V), maintains ±4 % output voltage tolerance (C-grade), and supports junction temperatures from 0 °C to 150 °C in TO-220FP package-commonly used for local on-card regulation in industrial power supplies and embedded control modules.

For engineers reviewing the L78M08CV-DG datasheet, L78M08CV-DG pinout, L78M08CV-DG application, or L78M08CV-DG equivalent, key selection criteria include dropout voltage (2 V), load regulation (80 mV max over 5–200 mA), supply voltage rejection (56 dB at 120 Hz), quiescent current (6 mA), and thermal resistance (R_thJC = 5 °C/W), all critical for stable low-noise 8 V rail generation in thermally constrained designs.

Technical Context

The L78M08CV-DG implements a monolithic PNP pass transistor architecture with internal current limiting, thermal shutdown, and SOA compensation-ensuring robustness under sustained overload or transient fault conditions. Its fixed 8 V output is trimmed during final test to meet ±4 % tolerance across temperature (0–125 °C) and load (5–350 mA).

Designed for simplicity and reliability, it requires only two external bypass capacitors (0.33 µF input, 0.1 µF output) for stability and improved transient response. No external feedback network is needed, and it does not support adjustable output without additional components-distinguishing it from LDOs or programmable regulators.

Key Specifications

Pinout & Package

Package: TO-220FP (Full Pack), 3-lead vertical mounting variant with insulated tab, RoHS-compliant and ECOPACK® certified.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78M08CDT-TR, L78M08CV-DG offers superior thermal performance in through-hole mounting; compared with MC78M08BDTG, it trades ±2 % tolerance for +25 °C higher junction limit-making it preferable for cost-sensitive, thermally demanding applications where ±4 % is acceptable.

Availability

L78M08CV-DG is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, medical patient monitor sensors, and point-of-sale terminal power management requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for L78M08CV-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 silicon solutions for automotive, industrial, and consumer markets-with over 40 years of linear regulator heritage.

The L78M series belongs to ST's precision 500 mA three-terminal regulator product line, engineered for ruggedness and simplicity in local on-card regulation-targeting applications where reliability, thermal resilience, and ease of use outweigh ultra-low dropout or ultra-low IQ requirements.

FAQ

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

The L78M08CV-DG requires a minimum input voltage of 10 V to maintain regulation, based on its 2 V typical dropout voltage at 350 mA. At lighter loads (<50 mA), dropout drops slightly, but design margin should retain ≥10.5 V input to ensure stability across temperature and line variations per datasheet Figure 9.

Can this regulator be used without input and output capacitors?

While the L78M08CV-DG is internally compensated and may function without capacitors in low-noise, low-impedance lab conditions, ST strongly recommends a 0.33 µF input capacitor (tantalum or ceramic) and 0.1 µF output capacitor. Omission risks instability under load transients or long input traces, as confirmed in Section 7.1 of DS0425 Rev 24.

Does the L78M08CV-DG support adjustable output voltage?

No-it is a fixed 8 V output device. However, external circuitry (e.g., resistor networks or op-amps as shown in Figures 19–22 of DS0425) can modify the output, but doing so voids guaranteed specifications like line/load regulation and thermal protection behavior. For adjustable designs, ST recommends the L200 or LD108x families.

How does the thermal shutdown behave during continuous overload?

Under sustained overload, the L78M08CV-DG enters thermal shutdown at ~150 °C junction temperature, ceasing output. It remains latched off until junction cools below ~135 °C, then automatically resumes regulation. This hysteresis prevents cycling and ensures safe cooldown-verified in thermal characterization data (Figure 8, DS0425 Rev 24).