onsemi MC78L24ACP

Overview

MC78L24ACP from Fairchild Semiconductor is a fixed-output +24 V, 100 mA positive voltage regulator in TO-92 package, featuring thermal overload protection, short-circuit current limiting, and ±5% output voltage tolerance at 25°C. It delivers stable DC power for low-current analog circuits, sensor interfaces, and microcontroller peripherals where input voltage ranges from 27 V to 40 V.

For engineers reviewing the MC78L24ACP datasheet, pinout, applications, or equivalent options, key selection criteria include dropout voltage (1.7 V), ripple rejection (34–45 dB at 120 Hz), load regulation (≤100 mV over 1–40 mA), and junction temperature range (0°C to +150°C).

Technical Context

The MC78L24ACP implements a monolithic three-terminal linear regulator architecture with internal reference voltage, error amplifier, pass transistor, short-circuit protection, and thermal shutdown circuitry. Its design ensures stable regulation without external components beyond recommended input/output bypass capacitors (0.33 µF and 0.1 µF).

It operates across an input voltage range of 27–40 V for 24 V output, maintains output accuracy under varying line (≤250 mV) and load (≤100 mV) conditions, and exhibits 200 µV/V_O output noise (10 Hz–100 kHz) and –2.0 mV/°C temperature coefficient.

Key Specifications

Pinout & Package

MC78L24ACP uses the TO-92 through-hole package (3-pin, straight lead configuration). Package dimensions: 4.58 mm × 3.60 mm × 14.47 mm (L×W×H), with 1.27 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L24ACZ, MC78L24ACP offers identical regulation performance but differs in branding and sourcing channel; compared with MC78L24ACD, it trades through-hole ease-of-use and prototyping flexibility for lower thermal resistance in SMT form.

Availability

MC78L24ACP is available at Aetrix Electronics and suitable for industrial sensor interfaces, legacy control panel upgrades, and test equipment power subsystems requiring stable component supply, long-lifecycle support, and TO-92 through-hole compatibility.

Supply support for MC78L24ACP 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

Fairchild Semiconductor was a leading designer of analog and power ICs, acquired by ON Semiconductor in 2016; its legacy linear regulator portfolio remains widely deployed and supported.

The MC78LXXA series was developed for cost-sensitive, low-power industrial and consumer applications requiring simple, robust fixed-voltage regulation without external components.

FAQ

What is the maximum input voltage for MC78L24ACP?

The absolute maximum input voltage for MC78L24ACP is 40 V DC. Operation above this level risks permanent damage. For reliable continuous use, input should remain within 27–38 V per the Electrical Characteristics table, ensuring adequate headroom above the 24 V output and 1.7 V dropout voltage.

Does MC78L24ACP require external capacitors?

Yes, MC78L24ACP requires two external bypass capacitors: a 0.33 µF capacitor between Input and Ground, and a 0.1 µF capacitor between Output and Ground. These stabilize regulation, improve transient response, and reduce output noise - omission may cause oscillation or poor load regulation.

What is the thermal shutdown threshold of MC78L24ACP?

The MC78L24ACP activates thermal shutdown when its internal junction temperature reaches approximately +150°C. This threshold is not user-adjustable and resets automatically once the die cools below the hysteresis point (~135°C), protecting the device during sustained overload or inadequate heatsinking.

Can MC78L24ACP deliver its full 100 mA output continuously?

MC78L24ACP can deliver up to 100 mA only under specific thermal conditions: ambient temperature ≤25°C, minimal PCB copper area, and no additional heatsinking. At higher temperatures or with limited board thermal mass, output current must be derated - e.g., ~60 mA at 70°C ambient - to maintain junction temperature ≤150°C.

Is MC78L24ACP pin-compatible with other MC78LXXA variants?

Yes, all MC78LXXA TO-92 variants (e.g., MC78L05ACP, MC78L12ACP) share identical pinout: Pin 1 = Output, Pin 2 = GND, Pin 3 = Input. This allows direct substitution across output voltages in existing designs, provided input voltage and load requirements are compatible with the new regulator's specifications.