STMicroelectronics L78L12ACZ-TR

Overview

L78L12ACZ-TR from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 12 V output at up to 100 mA, with ±4% output tolerance (A-grade), thermal overload protection, short-circuit protection, and no external components required. It serves as a local on-card regulator for noise-sensitive analog and digital subsystems in industrial control modules, sensor signal conditioning circuits, and low-power microcontroller power rails.

For engineers reviewing the L78L12ACZ-TR datasheet, L78L12ACZ-TR pinout, L78L12ACZ-TR application, or L78L12ACZ-TR equivalent, this device is selected for stable 12 V supply generation where low quiescent current (6.5 mA typ.), dropout voltage of 1.7 V, and 80 µV output noise are critical for precision analog front-ends and embedded MCU core logic.

Technical Context

The L78L12ACZ-TR employs internal current limiting and thermal shutdown circuitry, enabling robust operation without external protection components. Its architecture integrates a bandgap reference, error amplifier, and pass transistor in a monolithic silicon structure optimized for fixed-output regulation.

It operates across an input voltage range of 14.5 V to 27 V for guaranteed 12 V output, supports junction temperatures from 0 °C to 125 °C, and achieves supply voltage rejection of 37–42 dB at 120 Hz - making it suitable for noisy DC bus environments such as industrial PLC I/O modules and automotive body electronics.

Key Specifications

Pinout & Package

Supplied in TO-92 package (3-pin, through-hole), with standard pin configuration: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The package uses epoxy molding compound and is RoHS-compliant per ECOPACK2 specifications.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM78L12ACZ/NOPB and MC78L12ACP, the L78L12ACZ-TR offers superior output accuracy, lower noise, and better ripple rejection - making it the preferred choice for applications demanding stable 12 V bias in measurement, control, and communication subsystems.

Availability

L78L12ACZ-TR is available at Aetrix Electronics and suitable for industrial sensor interfaces, programmable logic controller I/O modules, and automotive body control units requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for L78L12ACZ-TR 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 industrial, automotive, and consumer markets.

The L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications requiring robust fixed-voltage regulation without external components.

FAQ

What is the maximum input voltage for L78L12ACZ-TR?

The absolute maximum DC input voltage is 35 V when the output is 12 V, per Table 1 in DS0424 Rev 30. For reliable operation with margin, ST recommends limiting input to ≤27 V under normal conditions to maintain thermal safety and specified electrical performance across temperature.

Can L78L12ACZ-TR be used in surface-mount designs?

No - L78L12ACZ-TR is packaged exclusively in TO-92 (through-hole). ST offers the pin-compatible L78L12ACD-TR in SO-8 and L78L12ACZ-TR in SOT-89 for surface-mount applications, but the -TR suffix on this part denotes TO-92 tape-and-reel packaging.

Does L78L12ACZ-TR require input and output capacitors?

Yes - ST specifies a minimum 0.33 µF ceramic capacitor at the input and 0.1 µF ceramic capacitor at the output, placed as close as possible to the respective pins. These are mandatory for stability, transient response, and noise suppression per Figure 13 and Section 6 of DS0424.

How does thermal performance differ between TO-92 and SO-8 packages of L78L12?

Per Table 2 in DS0424, TO-92 has R_thJA = 200 °C/W (no heatsink) versus SO-8's 55 °C/W (with 6 cm² copper pour). This means the TO-92 version dissipates significantly less power before reaching thermal shutdown - limiting practical continuous output current to ~40 mA at room temperature unless externally heatsinked.