onsemi MC78L08CP

Overview

MC78L08CP from ON Semiconductor (formerly Motorola) is a fixed-output +8.0 V, 100 mA positive linear voltage regulator in a plastic TO-92 package (Case 29), featuring internal short-circuit current limiting, thermal shutdown, and ±10% output voltage tolerance at +25°C. It operates with input voltages up to 35 V and requires only 2.0 V minimum headroom (dropout) for regulation, making it suitable for low-power industrial sensor interfaces and legacy microcontroller power rails.

For engineers reviewing the MC78L08CP datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specifications, thermal performance data, real-world load/line regulation behavior, and validated alternative options - all specific to the P-suffix TO-92 variant with 0°C to +125°C operating junction temperature range.

Technical Context

The MC78L08CP uses a monolithic bipolar design with built-in thermal overload protection that disables output when junction temperature exceeds safe limits, and internal current limiting that caps output at ~150 mA under short-circuit conditions. Its dropout voltage remains stable at 1.7 V (typ) across temperature and load, enabling reliable operation even with marginal input margins.

It exhibits 37 dB ripple rejection at 120 Hz (12–23 V input range) and 60 µV RMS output noise (10 Hz–100 kHz), supporting analog-sensitive applications such as precision sensor signal conditioning where low-noise, stable DC bias is required without external compensation capacitors in most configurations.

Key Specifications

Pinout & Package

MC78L08CP is housed in a 3-pin plastic TO-92 package (Case 29), with leads arranged in standard emitter-collector-base order. The package features axial lead configuration, compatible with through-hole PCB assembly and manual prototyping.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC78L08CP, MC78L08ACZ provides tighter output accuracy at the cost of higher unit price, while LM78L08ACZ offers second-source availability but requires validation for ±5% tolerance compliance in existing C-grade designs.

Availability

MC78L08CP is available at Aetrix Electronics and suitable for industrial sensor interfaces, legacy microcontroller power rails, and low-power LED biasing requiring stable component supply with long lifecycle support.

Supply support for MC78L08CP 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, and sensor solutions for automotive, industrial, and communications markets.

The MC78L00 series was designed as a cost-effective, rugged linear regulator family for low-current applications where simplicity, reliability, and thermal robustness outweigh efficiency concerns - targeting legacy systems and cost-sensitive embedded controls.

FAQ

What is the maximum input voltage rating for the MC78L08CP?

The MC78L08CP supports a maximum input voltage of 35 VDC when operating within its specified temperature range. This rating applies specifically to the P-suffix TO-92 variant and is derived from the absolute maximum ratings table in the Motorola Analog IC Device Data sheet. Exceeding 35 V risks permanent damage due to internal transistor breakdown, regardless of load current or ambient temperature.

Does the MC78L08CP require input and output capacitors for stable operation?

The MC78L08CP does not require external capacitors for basic stability, per the manufacturer's design guidance. However, a 0.33 µF input capacitor is recommended when the regulator is located more than a few centimeters from the main power supply filter, and a 0.1 µF output capacitor improves transient response. These values are explicitly validated for the MC78L08CP in the "Standard Application" schematic and Applications Information section.

What is the thermal resistance (θ_JA) of the MC78L08CP in its TO-92 package?

The MC78L08CP has a typical junction-to-ambient thermal resistance (θ_JA) of 200°C/W when mounted on a standard FR-4 PCB with no copper pour. This value is confirmed in Figure 5 of the Motorola datasheet and defines the device's ability to dissipate heat: at 100 mA and 2.0 V dropout (200 mW dissipation), junction temperature rise is ~40°C above ambient - well within the 0°C to +150°C operating range.

How does line regulation performance vary across the input voltage range for the MC78L08CP?

For the MC78L08CP, line regulation is specified as 20 mV maximum over an input range of 11–23 VDC at +25°C and 40 mA load. This means the output voltage changes by no more than ±20 mV as input varies across that span - a key parameter for designs using unregulated wall adapters or battery inputs with wide voltage swing. Performance degrades outside this range, with higher drift observed near absolute maximum (35 V) or minimum dropout (9.7 V) conditions.

Can the MC78L08CP be used as a current source, and what is the practical limit?

Yes, the MC78L08CP can be configured as a constant-current source by connecting a resistor between output and adjust/reference pins - though it lacks an explicit adjust pin, the standard current-source topology (Figure 7 in the datasheet) uses the regulator's internal reference and pass element. For MC78L08CP, maximum usable current is limited to ~100 mA by thermal constraints and internal current limiting; attempting higher currents triggers thermal shutdown or causes output collapse due to excessive die heating.