onsemi MC7808BT

Overview

MC7808BT from onsemi is a fixed-output, 8 V, 1.0 A positive linear voltage regulator in TO-220 package with internal thermal shutdown, short-circuit current limiting, and safe-area compensation. It delivers stable 8 V output across 5 mA–1.0 A load range with ≤2.0 V dropout at full load, supporting local regulation in industrial power supplies, automotive control modules, and embedded system rails.

For engineers reviewing the MC7808BT datasheet, pinout, applications, or equivalent options, this page provides verified electrical specs (VO = 7.7–8.3 V @ 25°C, Regline ≤ 6.0 mV, RR ≥ 62 dB), thermal performance (TJ max = +150°C), package dimensions (TO-220, heatsink tied to Pin 2), and validated alternatives for design-in and supply continuity.

Technical Context

The MC7808BT implements a monolithic series pass transistor architecture with built-in protection circuitry: thermal overload detection triggers shutdown before junction temperature exceeds +150°C, while short-circuit current limiting holds ISC ≤ 0.2 A at VIN = 35 V. Safe-area compensation dynamically reduces output current as VI–VO increases, preventing second breakdown under high-dissipation conditions.

It operates without external components for basic regulation but requires input bypassing (≥0.33 µF) when located >2 inches from bulk filter, and benefits from output capacitance (≥0.1 µF) to improve transient response. Ripple rejection is specified at 62 dB (11.5–18 V_IN, 120 Hz), and quiescent current remains stable at 3.3–8.0 mA across input voltage and load variations.

Key Specifications

Pinout & Package

MC7808BT uses the standard TO-220 package (Case 221AB), with metal tab (heatsink surface) electrically connected to Pin 2 (Ground). Adequate heatsinking is required to sustain 1.0 A output continuously.

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 NCV7808BDTRKG, the MC7808BT offers optimal balance of industrial-grade reliability, through-hole manufacturability, and cost efficiency for non-automotive applications requiring proven TO-220 compatibility and thermal robustness.

Availability

MC7808BT is available at Aetrix Electronics and suitable for industrial control power supplies, embedded system local regulation, and legacy equipment retrofit requiring stable component supply and long-term lifecycle support.

Supply support for MC7808BT 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

onsemi is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, and IoT applications.

The MC7800 series was designed as a rugged, pin-compatible family of fixed-output linear regulators targeting cost-sensitive, high-reliability applications where simplicity, protection integration, and thermal resilience are essential.

FAQ

What is the maximum input voltage for MC7808BT?

The absolute maximum input voltage for MC7808BT is 35 V DC, but the recommended operating range is 10.5 V to 23 V to ensure proper regulation and thermal management. Exceeding 23 V significantly increases power dissipation - for example, at 1.0 A output and 25 V input, PD ≈ 17 W - requiring substantial heatsinking to maintain TJ ≤ +150°C.

Does MC7808BT require input and output capacitors?

MC7808BT does not require output capacitance for stability, but a ≥0.1 µF ceramic or tantalum capacitor is recommended to improve transient response. An input bypass capacitor (≥0.33 µF) is required if the regulator is located more than ~2 inches from the main filter capacitor to prevent oscillation and ensure high-frequency stability.

Is MC7808BT pin-compatible with older 7808 variants?

Yes, MC7808BT uses the industry-standard TO-220 package with identical Pin 1 (Input), Pin 2 (Ground), Pin 3 (Output) assignment and mechanical footprint as legacy 7808 regulators, enabling direct replacement in existing PCB layouts without modification.

What is the thermal resistance of MC7808BT in TO-220 package?

The MC7808BT has a junction-to-case thermal resistance (R_JC) of 5.0°C/W and a junction-to-ambient resistance (R_JA) of 92°C/W with no heatsink. With a typical 1.5°C/W heatsink, total R_JA drops to ~20°C/W, allowing ~1.0 A continuous output at ambient temperatures up to +70°C.

How does MC7808BT handle short-circuit conditions?

MC7808BT limits short-circuit output current to approximately 0.2 A when VIN = 35 V, independent of output voltage. This current limit is enforced by internal circuitry and works in conjunction with thermal shutdown - if the short persists, junction temperature rises until shutdown activates at +150°C, then recovers automatically once cooled.