onsemi MC78L08ABD

Overview

MC78L08ABD from onsemi is a 100 mA, fixed +8.0 V positive linear voltage regulator in SOIC-8 package, featuring internal short-circuit current limiting, thermal shutdown, and dropout voltage of 1.7 V at 25°C. It operates across −40°C to +125°C and requires no external components for basic regulation in low-power embedded, automotive, and industrial power rails.

For engineers reviewing the MC78L08ABD datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs (VO = 7.7–8.3 V, RR = 37–57 dB, Regload ≤ 80 mV), thermal resistance (R_JA per Figure 8), SOIC-8 pin mapping, and two validated alternative regulators for design flexibility.

Technical Context

The MC78L08ABD implements a monolithic series-pass transistor architecture with built-in thermal overload protection and foldback current limiting. Its output voltage is trimmed during final test to ±3% tolerance (7.7–8.3 V) at 25°C and maintains regulation over input voltages from 10.5 V to 23 V.

Designed for stability without external capacitors in most applications, it achieves 57 dB ripple rejection at 120 Hz with 40 mA load and exhibits 60 µV RMS output noise (10 Hz–100 kHz). Dropout is defined as the minimum VI–VO differential required to maintain regulation within 2% of nominal output - consistently 1.7 V at 25°C.

Key Specifications

Pinout & Package

MC78L08ABD is housed in an SOIC-8 (Case 751) package with Pb-free finish. Pins 2, 3, 6, and 7 are electrically common to the die attach flag, reducing thermal resistance and improving power handling when mounted on adequate PCB copper.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L08ACDR2G, the MC78L08ABD offers guaranteed operation down to −40°C and shares qualification lineage with NCV automotive variants; versus TL78L08ACDR, it provides tighter output tolerance (±3% vs ±5%) and direct onsemi automotive support infrastructure.

Availability

MC78L08ABD is available at Aetrix Electronics and suitable for automotive body control modules, industrial sensor signal conditioning, and medical diagnostic equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC78L08ABD 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, sensing, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The MC78L00A Series was designed to deliver cost-effective, rugged, fixed-output linear regulation for space-constrained, thermally demanding applications where simplicity, reliability, and wide temperature operation are critical.

FAQ

What is the maximum input voltage for MC78L08ABD?

The absolute maximum input voltage for MC78L08ABD is 35 Vdc when operating across its full −40°C to +125°C junction temperature range. This rating is specified in the Absolute Maximum Ratings table and applies regardless of output load. Exceeding 35 Vdc risks permanent damage. For reliable regulation, the recommended input range is 10.5 V to 23 V, ensuring sufficient headroom above the 1.7 V dropout while staying within safe thermal limits. Always verify input transient conditions in your system.

Does MC78L08ABD require input and output capacitors?

MC78L08ABD does not require external capacitors for basic stability, but input bypassing with ≥0.33 µF (tantalum, ceramic, or film) is strongly recommended if the regulator is located more than a few centimeters from the power supply filter. An output capacitor of ≥0.1 µF improves transient response and reduces output impedance. These values are confirmed in the Standard Application schematic (Figure 2) and Applications Information section of the official datasheet for MC78L08ABD.

Is MC78L08ABD pin-compatible with other MC78L00A series regulators?

Yes - MC78L08ABD shares identical SOIC-8 pinout (1=VOUT, 2=GND, 3=GND, 4=VIN, 5=GND, 6=GND, 7=GND, 8=NC) with all MC78LxxABD and MC78LxxACD variants in the same package. This allows direct substitution between 5 V, 8 V, 9 V, 12 V, and 15 V versions without PCB changes, provided input voltage and thermal constraints remain valid for the new output voltage. Pin compatibility is explicitly confirmed in the PIN CONNECTIONS section of the MC78L00A datasheet.

What is the thermal resistance (R_JA) of MC78L08ABD in SOIC-8?

MC78L08ABD's junction-to-ambient thermal resistance (R_JA) is not a fixed value - it depends on PCB copper area and layout. The datasheet provides R_JA curves in Figure 8, showing values from ~120°C/W (with 170 mm² copper) down to ~70°C/W (with large symmetrical copper pours). Unlike TO-92 (R_JA = 200°C/W), SOIC-8 leverages pins 2, 3, 6, and 7 tied to the die flag for enhanced thermal conduction. Designers must consult Figure 8 and apply appropriate copper land patterns to meet thermal targets for their specific MC78L08ABD application.

Can MC78L08ABD be used as a current source?

Yes - the MC78L00A series, including MC78L08ABD, can be configured as a constant-current source using the circuit shown in Figure 9 of the datasheet. By connecting the input to a higher voltage, grounding the output through a resistor (R), and routing the load between input and ground, output current approximates I_O ≈ V_REF/R, where V_REF is the internal bandgap reference (~8 V for MC78L08ABD). This configuration exploits the regulator's internal current-limiting and thermal protection, making it suitable for LED biasing or sensor excitation where moderate accuracy suffices.