STMicroelectronics L7808CDT-TR

Overview

L7808CDT-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 VO = 5–18 V), maintains ±2.5% output tolerance over temperature and load, and is commonly used for local regulation in industrial power supplies, embedded control modules, and automotive body electronics.

For engineers reviewing the L7808CDT-TR datasheet, L7808CDT-TR pinout, L7808CDT-TR application, or L7808CDT-TR equivalent, key selection considerations include dropout voltage (2 V @ 1 A), load regulation (≤160 mV), supply voltage rejection (56 dB @ 120 Hz), and thermal resistance (R_thJA = 60 °C/W in TO-220FP package).

Technical Context

The L7808CDT-TR implements a monolithic silicon-based 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 to meet ±2.5% tolerance across –40 °C to 125 °C junction temperature range.

It requires only two external capacitors (CI ≥ 0.33 µF, CO ≥ 0.1 µF) for stability and ripple suppression, and supports operation with minimum load current of 5 mA. Dropout voltage remains constant at 2 V under full 1 A load at 25 °C, enabling predictable low-headroom design in 12 V rail systems.

Key Specifications

Pinout & Package

Supplied in TO-220FP package (3-pin, vertical mounting, isolated tab), with standard three-terminal configuration: Input (Pin 1), Ground (Pin 2), Output (Pin 3). The metal tab is electrically connected to Pin 2 (Ground), enabling direct heatsink attachment without insulation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7808CDT and MC7808CD2TR4G, the L7808CDT-TR provides the widest operating temperature range (–40 °C to 125 °C), certified industrial-grade reliability, and optimized thermal interface via isolated TO-220FP tab-making it preferred for automotive and harsh-environment deployments where long-term parametric stability is critical.

Availability

L7808CDT-TR is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, medical instrumentation, and test equipment requiring stable component supply and long-lifecycle support.

Supply support for L7808CDT-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, microcontroller, power, and sensing solutions for industrial, automotive, and consumer markets.

The L78 series belongs to ST's legacy positive voltage regulator IC product line, engineered for cost-sensitive, high-reliability local regulation in systems where simplicity, ruggedness, and proven field performance outweigh ultra-low quiescent current or adjustable output requirements.

FAQ

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

The L7808CDT-TR requires a minimum input voltage of 10.5 V to maintain 8 V output regulation under all conditions, including full 1.5 A load and maximum temperature. At 1 A load and 25 °C, the dropout is 2 V, so 10 V input would suffice-but 10.5 V is the guaranteed minimum per datasheet specifications across temperature and process variation.

Can this regulator be used without a heatsink?

Yes, for low-power operation: at ≤500 mA load and ambient temperatures ≤50 °C, the TO-220FP package's R_thJA = 60 °C/W allows self-cooled operation. At 1 A and 25 °C ambient, junction temperature rises ~60 °C above ambient-reaching ~85 °C, well below thermal shutdown. For sustained >750 mA in enclosed or hot environments, a heatsink is recommended.

Does the L7808CDT-TR require input and output capacitors?

Yes-ST specifies a minimum 0.33 µF ceramic capacitor at the input and 0.1 µF ceramic capacitor at the output, placed as close as possible to the respective pins. These capacitors ensure stability, improve transient response, and reduce high-frequency noise; omitting them may cause oscillation or poor regulation under dynamic load changes.

How does the L7808CDT-TR behave during short-circuit events?

Under short-circuit, the device limits output current to approximately 0.45 A (typical), enters thermal shutdown if junction temperature exceeds ~150 °C, and automatically recovers once cooled. This dual-layer protection (current limit + thermal shutdown) prevents damage without external circuitry, enabling safe operation even with indefinite output shorts at room temperature.