onsemi MC78L24ACPRA

Overview

MC78L24ACPRA from onsemi is a 100 mA, fixed +24 V positive linear voltage regulator in TO-92 package with internal short-circuit current limiting, thermal shutdown, and no external components required. It delivers stable output under input voltages up to 38 V and supports industrial temperature range (0°C to +125°C), commonly used in power supply rails for analog sensors and microcontroller peripherals.

For engineers reviewing the MC78L24ACPRA datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (1.7 V typical), load regulation (≤100 mV over 1–100 mA), ripple rejection (31–45 dB at 120 Hz), thermal resistance (200°C/W in TO-92), and Pb-free TO-92 packaging compliance.

Technical Context

The MC78L24ACPRA implements a monolithic series-pass transistor regulator architecture with built-in protection circuitry: thermal overload shutdown activates at ~150°C junction temperature, and internal current limiting caps output at ~150 mA. Its design eliminates need for external compensation capacitors in most low-noise, low-current applications.

It operates as a three-terminal device requiring only input, ground, and output connections. Input voltage must remain ≥27 V (min) to maintain regulation, with maximum rated input at 38 V DC. Output noise is 200 µV RMS (10 Hz–100 kHz), and line regulation is specified at ≤300 mV across full input range.

Key Specifications

Pinout & Package

MC78L24ACPRA uses the standard TO-92 (Case 029) plastic package with straight leads and Pb-free finish. Pin 1 is Output, Pin 2 is Ground, Pin 3 is Input - verified per onsemi datasheet Figure 1 and ordering table.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L24ACPRA, MC78L24ACPG offers identical performance in a different packaging format, while LM78L24ACZ trades tighter regulation and lower noise for broader legacy compatibility and lower unit cost - making MC78L24ACPRA optimal for new designs demanding industrial-grade stability and low-noise operation.

Availability

MC78L24ACPRA is available at Aetrix Electronics and suitable for industrial sensor power, microcontroller I/O rail generation, legacy equipment retrofit, and test & measurement auxiliary supply requiring stable component supply, long-term lifecycle support, and RoHS-compliant through-hole packaging.

Supply support for MC78L24ACPRA 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 delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The MC78LxxA series was designed specifically for cost-sensitive, low-power industrial and consumer systems needing reliable fixed-voltage regulation without external components - emphasizing ruggedness, thermal safety, and ease of integration.

FAQ

What is the maximum input voltage for MC78L24ACPRA?

The MC78L24ACPRA supports a maximum input voltage of 40 V DC per absolute maximum ratings. For guaranteed regulation and full parameter compliance, input must be between 28 V and 38 V DC. Operation above 38 V risks exceeding thermal limits or triggering internal protection circuits, especially at elevated ambient temperatures or high load currents.

Does MC78L24ACPRA require input and output capacitors?

The MC78L24ACPRA does not require external capacitors for basic stability, but onsemi recommends a 0.33 µF input capacitor when connected via long traces to the power source, and a 0.1 µF output capacitor to improve transient response. These values are validated in the standard application circuit (Figure 2) and do not affect regulation integrity under nominal conditions.

What is the thermal resistance of MC78L24ACPRA in its TO-92 package?

The MC78L24ACPRA in TO-92 (Case 029) has a thermal resistance of 200°C/W (Junction-to-Ambient) with no heatsink. This value assumes standard PCB mounting on FR-4 with minimal copper area. Derating is required above 25°C ambient - e.g., maximum continuous power drops to ~400 mW at 50°C ambient - as shown in Figure 7 of the datasheet.

Is MC78L24ACPRA suitable for automotive applications?

The MC78L24ACPRA is rated for 0°C to +125°C operation and is Pb-free, but it is not AEC-Q100 qualified. For automotive use, onsemi offers the NCV78L24ABPRPG variant (−40°C to +125°C, AEC-Q100 Grade 3, PPAP-capable). MC78L24ACPRA is intended for industrial and commercial applications only.

How does MC78L24ACPRA handle short-circuit conditions?

The MC78L24ACPRA features internal short-circuit current limiting that restricts output current to approximately 150 mA during sustained faults. Combined with thermal shutdown (triggered near 150°C junction temperature), this dual-protection scheme prevents damage during accidental shorts, enabling safe auto-recovery once fault is removed and die temperature falls below trip threshold.