onsemi NCP7808TG

Overview

NCP7808TG from onsemi is a 3-pin, fixed-output, positive linear voltage regulator delivering 8.0 V ±4% at up to 1.0 A continuous output current. It features internal thermal shutdown, short-circuit current limiting, safe-area compensation, and enhanced ESD protection (HBM 4 kV). Designed as a rugged replacement for MC7808, it operates with input voltages from 10.5 V to 35 V and supports industrial power supply and embedded system biasing.

For engineers reviewing the NCP7808TG datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (2.0 V at 1.0 A), line regulation (1.0 mV typical over 11–17 V input), load regulation (3.7 mV over 5 mA–1.5 A), ripple rejection (72 dB at 120 Hz), and TO-220 thermal resistance (R_JA = 65 °C/W).

Technical Context

The NCP7808TG implements a classic series-pass linear regulator architecture with an integrated NPN pass transistor, internal reference, error amplifier, and protection circuitry. Its safe-area compensation dynamically reduces short-circuit current as V_IN–V_OUT increases, preventing second breakdown under fault conditions.

Thermal overload protection activates at T_J ≥ 150 °C, forcing shutdown until junction temperature falls below ~135 °C. Input-to-output reverse-current protection is provided by an internal 1 Ω diode path rated for ≤5 A peak surge (≤ several ms); external protection diode recommended when large output capacitance and rapid input collapse occur.

Key Specifications

Pinout & Package

Package: TO-220-3 (Case 221AB), Pb-free, vertical mounting with heatsink surface electrically connected to Pin 2 (GND). Pin 1 is isolated input; Pin 3 is isolated output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC7808CT and LM7808CD2T, the NCP7808TG offers superior fault resilience (safe-area compensation, 4 kV HBM), identical TO-220 thermal performance, and Pb-free compliance-making it optimal for new industrial and automotive designs demanding long-term reliability.

Availability

NCP7808TG is available at Aetrix Electronics and suitable for industrial power supplies, embedded system bias rails, and automotive body control modules requiring stable component supply across multi-year production cycles.

Supply support for NCP7808TG 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 (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The NCP7800 series was designed as a rugged, drop-in upgrade to the MC7800 family-targeting industrial and automotive applications where thermal resilience, ESD robustness, and long-term supply stability are critical.

FAQ

What is the minimum input voltage required for stable operation of the NCP7808TG?

The NCP7808TG requires a minimum input voltage of 10.0 V under full load (1.0 A), calculated as V_OUT + V_DO = 8.0 V + 2.0 V. At lighter loads, the dropout voltage decreases, but design margin should maintain ≥10.5 V input per the datasheet's operating range specification. Below this threshold, regulation degrades and output sags.

Does the NCP7808TG require external capacitors for stability?

The NCP7808TG does not require output capacitance for stability, but a ≥0.1 µF ceramic or tantalum capacitor at the output significantly improves transient response. An input bypass capacitor (≥0.33 µF) is recommended if the regulator is located >2 inches from the main filter capacitor to suppress high-frequency noise and prevent oscillation under dynamic load changes.

How does the safe-area compensation in the NCP7808TG improve reliability?

Safe-area compensation in the NCP7808TG dynamically reduces short-circuit current as the input-output differential voltage increases-preventing localized hot-spot formation and second breakdown in the pass transistor during sustained overloads or output shorts. This extends device lifetime and avoids catastrophic failure modes common in uncompensated regulators.

Can the NCP7808TG be used as a constant-current source?

Yes-the NCP7808TG can be configured as a constant-current source by connecting a resistor between output and load ground, leveraging its internal current-limiting and thermal protection. The output current is approximated by I_OUT ≈ V_REF/R, where V_REF is the internal bandgap reference (~1.25 V). For example, a 1.25 Ω resistor yields ~1.0 A, matching the NCP7808TG's rated output capability.

What thermal management is required for 1.0 A continuous operation of the NCP7808TG?

At 1.0 A output with 12 V input (4 V differential), power dissipation is ~4 W. With R_JA = 65 °C/W, junction temperature rise is ~260 °C above ambient-exceeding the 125 °C max operating limit. A heatsink reducing R_JA to ≤30 °C/W (e.g., 5°C/W R_JC + 25°C/W heatsink) is mandatory. Derating to 0.5 A is advised without heatsink.