STMicroelectronics L78S75CV

Overview

L78S75CV from STMicroelectronics is a three-terminal fixed-output positive linear voltage regulator delivering 7.5 V at up to 2 A, featuring internal current limiting, thermal shutdown, and safe operating area (SOA) protection. It operates with a minimum input voltage of 10.5 V (for ≤1 A load), exhibits 16 mΩ output resistance, and maintains ±0.5 V output accuracy over temperature and load. It is used for local on-card regulation in industrial power supplies and embedded control modules where robustness against short circuits and thermal overload is required.

For engineers reviewing the L78S75CV datasheet, L78S75CV pinout, L78S75CV application, or L78S75CV equivalent, key selection criteria include dropout behavior under 2 A load, thermal resistance (5 °C/W junction-to-case), ripple rejection (48 dB at 120 Hz), and compatibility with TO-220 heatsinking layouts in high-reliability DC power distribution.

Technical Context

The L78S75CV implements a monolithic series pass transistor architecture with built-in foldback current limiting and thermal foldback that reduces output current before junction temperature exceeds 150 °C. Its SOA protection prevents secondary breakdown during transient overloads by dynamically constraining I_O × V_CE product.

It requires no external compensation and remains stable without an output capacitor, though a 0.33 µF input and 0.1 µF output ceramic capacitor are recommended for transient response improvement. Input voltage range spans 10.5 V to 25 V for full 2 A operation, with peak short-circuit current limited to 3 A.

Key Specifications

Pinout & Package

Supplied in TO-220 package with standard 3-pin configuration: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The metal tab is electrically connected to Pin 2 (Ground) and serves as thermal interface to heatsink.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7808CDT, L78S75CV provides exact 7.5 V output and 33% higher current capability; versus LD1085V75, it trades lower dropout for superior intrinsic ruggedness-critical in unattended industrial equipment where field-replaceability is constrained.

Availability

L78S75CV is available at Aetrix Electronics and suitable for industrial PLC power rails, automotive body control modules, medical infusion pump logic supplies, and point-of-load regulation in test equipment requiring stable component supply across multi-year production cycles.

Supply support for L78S75CV 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The L78S series belongs to ST's legacy linear regulator product line, engineered specifically for high-reliability local regulation in harsh environments where thermal resilience, short-circuit survivability, and long-term parametric stability are prioritized over ultra-low quiescent current or ultra-low dropout.

FAQ

Is L78S75CV compatible with standard TO-220 heatsinks?

Yes - the L78S75CV uses a standard TO-220 package with Pin 2 (Ground) connected to the metal tab, enabling direct mechanical and thermal attachment to commercially available TO-220 heatsinks. For 2 A continuous operation, a heatsink with thermal resistance ≤25 °C/W (junction-to-ambient) is required to keep junction temperature below 150 °C at 25 °C ambient.

Does L78S75CV require an output capacitor for stability?

No - the L78S75CV is internally compensated and remains stable without an output capacitor. However, a 0.1 µF ceramic capacitor placed directly at the output pin significantly improves load transient response and reduces high-frequency noise, especially when powering digital ICs with fast switching currents.

What is the minimum input voltage needed to sustain 2 A output at 7.5 V?

The minimum input voltage is 9.5 V at 1 A load per datasheet Table 5, but for 2 A, the dropout voltage rises to ~2.0 V due to pass transistor saturation and PCB trace resistance. Thus, ≥9.5 V + 2.0 V = 11.5 V is recommended for reliable 2 A operation across temperature and unit variation.

Can L78S75CV be used in adjustable configurations?

Yes - although optimized as a fixed 7.5 V regulator, the L78S75CV can be configured as an adjustable regulator using external resistors and a Zener diode per Figure 19 and Figure 20 in the datasheet. This enables output voltages from 7 V to 30 V, but compromises guaranteed accuracy, line/load regulation, and thermal protection margins compared to fixed-voltage use.