STMicroelectronics L78L12ACUTR

Overview

L78L12ACUTR from STMicroelectronics is a fixed +12 V, 100 mA positive voltage regulator in SOT-89 package, featuring thermal overload protection, short-circuit current limiting, and ±4% output voltage tolerance at 25 °C. It delivers stable local regulation for low-power microcontroller peripherals, sensor interfaces, and industrial I/O modules with no external components required.

For engineers reviewing the L78L12ACUTR datasheet, L78L12ACUTR pinout, L78L12ACUTR application, or L78L12ACUTR equivalent, this page provides verified electrical characteristics, thermal performance data, real-world use cases, and validated alternative parts for embedded power design and BOM optimization.

Technical Context

The L78L12ACUTR implements a monolithic three-terminal linear regulator architecture with internal current limiting (150 mA typical short-circuit current), thermal shutdown activation at ~165 °C junction temperature, and inherent stability without external compensation. Its dropout voltage is 1.7 V at 40 mA load, enabling operation from as low as 13.7 V input when delivering full-rated 100 mA output.

It operates across an input voltage range of 14.5 V to 27 V for guaranteed 12 V output regulation, supports junction temperatures from 0 to 125 °C, and achieves 37–42 dB supply voltage rejection at 120 Hz under 40 mA load - critical for noise-sensitive analog and mixed-signal subsystems.

Key Specifications

Pinout & Package

SOT-89 package: 3-pin surface-mount device with exposed die-attach pad for enhanced thermal conduction; pin 1 = Input, pin 2 = Ground, pin 3 = Output.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L12ACZ/NOPB and TL78L12ACDR, L78L12ACUTR offers superior thermal management via SOT-89's 55 °C/W R_thJA, lower 80 µV noise, and higher 37–42 dB supply rejection - making it optimal for noise-sensitive, medium-current embedded systems where reliability and signal fidelity are prioritized.

Availability

L78L12ACUTR is available at Aetrix Electronics and suitable for industrial sensor interfaces, low-power MCU power rails, and programmable logic controller I/O modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for L78L12ACUTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for automotive, industrial, and consumer markets.

L78L12ACUTR belongs to the L78L series of three-terminal positive voltage regulators, engineered specifically for local on-card regulation in space-constrained embedded systems where simplicity, robustness, and low-noise performance are essential.

FAQ

What is the maximum input voltage for L78L12ACUTR?

The absolute maximum DC input voltage is 35 V for VO = 12 V operation, per Table 1 in DS0424 Rev 30. For reliable continuous regulation, ST specifies 14.5 V to 27 V input range - exceeding 27 V risks thermal overload or degraded line regulation beyond 250 mV.

Can L78L12ACUTR be used in parallel for higher current?

No - the L78L12ACUTR lacks built-in current-sharing circuitry and exhibits output voltage mismatch (±4%) that causes unequal current distribution. Parallel connection may result in thermal runaway or premature failure; use a single higher-current regulator or external pass transistor instead.

Is a heatsink required for 100 mA operation?

A dedicated heatsink is not required, but PCB copper area is essential: ST specifies 6 cm² of 2-oz copper connected to the exposed thermal pad to achieve R_thJA = 55 °C/W. Without this, junction temperature rises rapidly - at 100 mA and 20 V input, power dissipation is 0.8 W, raising T_J by ~44 °C above ambient.

Does L78L12ACUTR support adjustable output voltage?

No - L78L12ACUTR is a fixed +12 V regulator. While Figure 16 in DS0424 shows an external resistor network to create an adjustable variant, that configuration uses the L78LxxAC base part as a reference and requires additional components; the L78L12ACUTR itself has no adjustment pin or internal flexibility.