onsemi MC78L15ABP

Overview

MC78L15ABP from onsemi is a 15 V, 100 mA fixed-output linear voltage regulator in TO-92 package, featuring internal short-circuit current limiting, thermal overload protection, and no external components required for basic operation. It delivers stable regulation across −40°C to +125°C junction temperature, with typical dropout voltage of 1.7 V and output voltage tolerance of ±4% at +25°C - ideal for low-power sensor interfaces and microcontroller supply rails in industrial control modules.

For engineers reviewing the MC78L15ABP datasheet, pinout, applications, or equivalent options, key selection criteria include its guaranteed −40°C to +125°C operating range, 15 V output accuracy (14.4–15.6 V), 34–39 dB ripple rejection at 120 Hz, 90 µV RMS output noise, and TO-92 thermal resistance of 200°C/W - all critical for reliable operation in thermally constrained embedded systems.

Technical Context

The MC78L15ABP implements a monolithic series-pass transistor architecture with built-in thermal shutdown and foldback current limiting. Its internal reference and error amplifier maintain regulation without external feedback components, enabling single-supply operation with only input and output bypass capacitors.

Designed for fixed-voltage applications, it requires a minimum input-to-output differential of 2.0 V under ripple conditions and exhibits load regulation of ≤25 mV (1–100 mA) and line regulation of ≤130 mV (17.5–30 V input). Dropout behavior is defined as 2% deviation from nominal output voltage.

Key Specifications

Pinout & Package

MC78L15ABP uses the TO-92 (Case 029) plastic package with straight leads, Pb-free construction, and standard through-hole mounting. Thermal performance assumes PCB copper area per Figure 7; no heatsink required for ≤312 mW dissipation at 70°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L15ACPG, the MC78L15ABP enables operation down to −40°C - critical for outdoor industrial gear - while the NCV78L15ABPRPG adds automotive-grade reliability and documentation without altering pinout or thermal design.

Availability

MC78L15ABP is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller power supplies, and automotive body control modules requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for MC78L15ABP 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, and sensing technologies for automotive, industrial, and cloud infrastructure markets.

The MC78L00A Series was designed as a cost-effective, rugged fixed-voltage regulator family for low-current applications where simplicity, thermal resilience, and wide temperature operation outweigh programmability or ultra-low quiescent current needs.

FAQ

What is the minimum input voltage required for stable operation of the MC78L15ABP?

The MC78L15ABP requires the input voltage to remain at least 2.0 V above the output voltage - i.e., ≥17.0 V - even at the lowest point of input ripple. This ensures regulation is maintained across the full −40°C to +125°C operating range and under worst-case load transients. Below this differential, dropout occurs and output voltage drops proportionally.

Does the MC78L15ABP require external capacitors for stability?

The MC78L15ABP does not require external compensation capacitors for basic stability, but a 0.33 µF input bypass capacitor is recommended when connected via long traces to the power supply filter, and a 0.1 µF output capacitor improves transient response. These values are specified in the standard application circuit on page 2 of the datasheet.

How does thermal shutdown work in the MC78L15ABP?

The MC78L15ABP incorporates internal thermal overload protection that disables the pass transistor when junction temperature reaches approximately 150°C. Once the die cools sufficiently (typically by >20°C), regulation automatically resumes. This cycle prevents permanent damage during sustained overload or poor heatsinking conditions.

Can the MC78L15ABP be used as a current source?

Yes - the MC78L15ABP can be configured as a constant-current source by connecting a resistor between output and ground, with the load referenced to V_IN. Per Figure 9 in the datasheet, output current I_O ≈ 15 V / R, though bias current (up to 6.5 mA at +125°C) introduces minor error. Dissipation must remain within thermal limits.

Is there a drop-in replacement for the MC78L15ABP with improved PSRR?

No direct drop-in replacement with higher PSRR exists in the same TO-92 footprint and pinout. The MC78L15ABP achieves 34–39 dB at 120 Hz; alternatives like the TL750L15 offer better ripple rejection but differ in pinout, quiescent current, and thermal characteristics - requiring layout and validation changes. For higher PSRR, consider redesigning with a two-stage filter or low-noise LDO such as the NCP1117ST15T3G.