STMicroelectronics L7808CD2T-TR

Overview

L7808CD2T-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 8 V 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 8 V output), maintains ±2.5% output tolerance over temperature and load, and is commonly used in industrial power supplies, embedded control modules, and local on-card regulation for microcontroller-based systems.

For engineers reviewing the L7808CD2T-TR datasheet, L7808CD2T-TR pinout, L7808CD2T-TR application, or L7808CD2T-TR equivalent, key selection criteria include dropout voltage (2 V @ 1 A), load regulation (≤160 mV), supply voltage rejection (56 dB @ 120 Hz), quiescent current (8 mA), and thermal resistance (R_thJA = 62.5 °C/W in D²PAK).

Technical Context

This device implements a monolithic series pass transistor architecture with internal current limiting, thermal shutdown, and SOA protection-enabling robust operation without external protection circuitry. Its fixed 8 V output is trimmed during manufacturing and stabilized across –40 °C to 125 °C junction temperature range.

The regulator requires only two external capacitors (0.33 µF input, 0.1 µF output) for stability and exhibits low output noise (52 µV/√Hz, 10 Hz–100 kHz) and low output resistance (16 mΩ @ 1 kHz), supporting clean power delivery in noise-sensitive analog and mixed-signal circuits.

Key Specifications

Pinout & Package

The L7808CD2T-TR is housed in a surface-mount D²PAK (TO-263) package with standard three-terminal configuration: Input (Pin 1), Ground (Pin 2), Output (Pin 3).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7808CDT/NOPB and MC7808CD2TG, the L7808CD2T-TR offers superior supply rejection (56 dB vs. ≤50 dB), lower output noise (52 µV/√Hz vs. ≥65 µV/√Hz), and tighter output tolerance (±2.5% vs. ±3%), making it optimal for industrial and medical applications demanding stable, clean 8 V rails.

Availability

L7808CD2T-TR is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical infusion pumps, and point-of-sale terminals requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for L7808CD2T-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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L78 series is ST's flagship family of three-terminal positive linear regulators, engineered for ruggedness, ease of use, and broad applicability in local on-card regulation across industrial, automotive, and medical equipment.

FAQ

What is the minimum input voltage required for regulation at full 1.5 A load?

The L7808CD2T-TR requires a minimum input voltage of 10.5 V to maintain 8 V output at 1.5 A, based on its 2 V dropout specification. At lower input voltages, output collapses linearly; operation below 10.5 V is not guaranteed per datasheet Table 12. Input capacitance ≥0.33 µF is mandatory to prevent instability during transient load steps.

Can this regulator be used without a heatsink at 1 A continuous load?

At 1 A with 15 V input (7 V drop), power dissipation is ~7 W. With R_thJA = 62.5 °C/W, junction temperature rise would exceed 437 °C - far beyond the 125 °C limit. A heatsink reducing R_thJA to ≤15 °C/W (or forced air) is mandatory. PCB copper area (≥4 cm² 2 oz Cu) alone is insufficient for 1 A continuous operation.

Does the D²PAK package's exposed tab connect to a specific pin electrically?

Yes - the exposed metal tab on the D²PAK package is internally connected to Pin 2 (Ground). This must be soldered to a large PCB ground plane for both thermal conduction and electrical reference integrity. Floating or insulated mounting degrades thermal performance and may cause instability due to ground impedance.

How does the L7808CD2T-TR behave during input reverse polarity or output short-circuit events?

The device has no reverse-polarity protection; applying negative input voltage will damage it. During output short-circuit, current is limited to ~0.45 A (typ.), and thermal shutdown activates if junction temperature exceeds ~165 °C. Recovery is automatic after cooldown. External reverse-battery protection (e.g., series Schottky diode) is strongly recommended in automotive applications.