STMicroelectronics L7805CDT-TR

Overview

L7805CDT-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 5 V output with up to 1.5 A continuous current, ±2 % output voltage tolerance at 25 °C, thermal overload and short-circuit protection, and 2 V dropout voltage at 1 A - widely used for local regulation in industrial power supplies, embedded microcontroller boards, and automotive body electronics.

For engineers reviewing the L7805CDT-TR datasheet, L7805CDT-TR pinout, L7805CDT-TR application, or L7805CDT-TR equivalent, key selection criteria include guaranteed 5 V output stability across -40 to 125 °C (AB grade), junction-to-case thermal resistance of 5 °C/W in TO-220FP package, load regulation ≤100 mV from 5 mA to 1.5 A, and supply voltage rejection of 62 dB at 120 Hz.

Technical Context

This IC implements a monolithic series pass transistor architecture with internal current limiting, safe operating area (SOA) protection, and thermal shutdown circuitry - enabling robust operation without external protection components. Its fixed-output design eliminates need for feedback resistors, while internal compensation ensures stability with standard 0.33 µF input and 0.1 µF output capacitors.

The device operates over input voltages from 7 V to 35 V for 5 V output, supports minimum load current of 5 mA, and maintains regulation under transient loads up to 2.2 A peak short-circuit current. Junction temperature range is specified from –40 °C to +125 °C for the AB version, matching automotive and industrial ambient requirements.

Key Specifications

Pinout & Package

Supplied in TO-220FP package - a full-packaged variant of TO-220 with insulated backplate, enabling direct heatsink mounting without isolation hardware. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output (top view, tab facing down).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7805CDT, L7805CDT-TR offers wider temperature qualification and tighter thermal specs; versus MC7805BDTG, it delivers superior supply rejection and lower quiescent current - making it preferred for automotive and high-reliability embedded systems where noise and thermal margin are critical.

Availability

L7805CDT-TR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, embedded development boards, and consumer appliance control panels requiring stable component supply and long-term lifecycle support.

Supply support for L7805CDT-TR 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 power management applications.

The L78 series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-cost, fixed-voltage local regulation in harsh environments - emphasizing fault tolerance, thermal resilience, and ease of integration.

FAQ

What is the minimum input voltage required for stable 5 V output at 1.5 A?

The L7805CDT-TR requires a minimum input voltage of 7 V to maintain regulation at full 1.5 A load, based on its 2 V dropout specification. At lower input voltages - e.g., 6.5 V - output voltage will drop below 5 V and regulation is lost. Input capacitance of at least 0.33 µF ceramic must be placed within 10 mm of Pin 1 to prevent oscillation.

Can this regulator be used without a heatsink?

Yes, for loads ≤500 mA at ambient temperatures ≤50 °C, the TO-220FP package can operate without an external heatsink, given its 60 °C/W junction-to-ambient thermal resistance. Above that, thermal derating applies: at 1 A, junction temperature rise exceeds safe limits without heatsinking. Use R_thJC = 5 °C/W and calculate heatsink size using actual power dissipation (P_D = (V_IN – 5 V) × I_OUT).

Does L7805CDT-TR require output capacitance for stability?

Yes - a minimum 0.1 µF ceramic capacitor must be placed directly at the output pin (Pin 3) to ensure stability across all load and input conditions. Larger values (e.g., 10–100 µF electrolytic) improve transient response but do not replace the mandatory 0.1 µF ceramic. Omitting this capacitor risks oscillation and output voltage overshoot during load steps.

How does the internal current limit behave during a short circuit?

Under short-circuit conditions, the L7805CDT-TR limits output current to approximately 0.75 A (typical), reducing power dissipation and preventing immediate failure. If sustained, thermal shutdown activates at ~165 °C junction temperature, turning off the output until cooldown. After shutdown, the device automatically recovers once junction temperature falls by ~20 °C - no reset signal required.