STMicroelectronics L7805CT

Overview

L7805CT from STMicroelectronics is a three-terminal positive fixed-voltage linear regulator delivering 5 V ±2% output at up to 1.5 A, featuring thermal overload protection, short-circuit protection, and safe operating area (SOA) protection. It operates with input voltages up to 35 V (for 5 V output), maintains regulation down to 5 mA load, and is widely deployed in industrial control power supplies, embedded microcontroller boards, and automotive body electronics for local on-card voltage stabilization.

For engineers reviewing the L7805CT datasheet, L7805CT pinout, L7805CT application, or L7805CT equivalent, key selection criteria include dropout voltage (2 V @ 1 A), output noise (40 µV/√Hz), line/load regulation performance (≤100 mV), and thermal resistance (R_thJA = 50 °C/W in TO-220), critical for heatsink-limited designs and ambient temperature robustness.

Technical Context

The L7805CT implements a monolithic bipolar linear regulator architecture with internal current limiting, thermal shutdown, and SOA protection-no external components required for basic operation. Its feedback loop stabilizes output against line variations (VI = 7–25 V) and load changes (IO = 5 mA–1.5 A) across junction temperatures from 0 to 125 °C.

It uses a standard three-pin configuration (Input, Ground, Output) and relies on external capacitors (CI ≥ 0.33 µF, CO ≥ 0.1 µF) for stability and transient response. Ripple rejection reaches 62 dB at 120 Hz, and output resistance is 17 mΩ at 1 kHz-enabling stable low-noise 5 V rails for analog and digital circuitry.

Key Specifications

Pinout & Package

Supplied in TO-220 package with standard 3-pin vertical mounting footprint and metal tab connected to ground for thermal conduction and mechanical anchoring.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7805CDT and MC7805BDTRKG, the L7805CT offers superior supply voltage rejection (62 dB) and lower output noise (40 µV/√Hz), making it better suited for mixed-signal systems where analog integrity is prioritized over absolute max temperature rating.

Availability

L7805CT is available at Aetrix Electronics and suitable for industrial PLCs, automotive body electronics, embedded microcontroller boards, and legacy instrumentation requiring stable component supply, long lifecycle support, and TO-220 package compatibility.

Supply support for L7805CT 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 since 1987.

The L78 series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, high-reliability applications demanding robust protection, wide input range, and drop-in compatibility with industry-standard 78xx footprints.

FAQ

What is the minimum input voltage required for stable 5 V output at 1 A?

The L7805CT requires a minimum input voltage of 7 V to maintain regulation at 1 A load, based on its 2 V dropout specification at 25 °C. At elevated junction temperatures or with reduced heatsinking, the dropout may increase-designers should verify margin using R_thJA = 50 °C/W and worst-case ambient conditions.

Can L7805CT be used without an input bypass capacitor?

No. An input capacitor of at least 0.33 µF (ceramic or tantalum) is mandatory per the datasheet to prevent oscillation and ensure stability, especially with long input traces or high-impedance sources. Omitting it risks high-frequency instability and potential device failure under transient load conditions.

How does thermal shutdown behave during continuous overload?

Under sustained overload, the L7805CT enters thermal shutdown at ~165 °C junction temperature, cutting output until junction cools to ~140 °C, then resuming regulation. This cycle repeats autonomously-no external reset is needed-but repeated cycling degrades long-term reliability; proper heatsinking is essential for continuous 1 A operation.

Is L7805CT RoHS compliant and lead-free?

Yes. The L7805CT is manufactured in STMicroelectronics' RoHS-compliant, lead-free TO-220 package (Pb-free plating, halogen-free molding compound), meeting EU Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level MSL3 requirements for surface-mount assembly.