STMicroelectronics L79L12ACD13TR

Overview

L79L12ACD13TR from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -12 V at up to 100 mA, featuring internal current limiting, thermal shutdown, and short-circuit protection. It requires no external components and is specified for operation from -14.5 V to -27 V input, with ±5% output tolerance, 1.7 V dropout, and 80 µV RMS output noise (10 Hz–100 kHz) - used for local regulation on PCBs in industrial control and analog signal conditioning circuits.

For engineers reviewing the L79L12ACD13TR datasheet, L79L12ACD13TR pinout, L79L12ACD13TR application, or L79L12ACD13TR equivalent, key selection criteria include guaranteed -12 V output accuracy over temperature (-40 °C to +125 °C), low quiescent current (6.5 mA typ. at 25 °C), high PSRR (37–42 dB at 120 Hz), and TO-92 package compatibility with standard through-hole mounting and heat-sinkable lead-frame design.

Technical Context

The L79L12ACD13TR implements a monolithic PNP pass transistor architecture with built-in thermal overload and short-circuit protection circuitry, eliminating need for external foldback or shutdown logic. Its internal current limit and junction temperature sensing activate before damage thresholds are reached, enabling robust operation without auxiliary protection components.

It operates as a fixed-voltage, negative-polarity regulator with a minimum input-to-output differential of 1.7 V (dropout), supporting stable regulation across IO = 1–100 mA and VI = -14.5 V to -27 V. Load and line regulation are specified at ≤100 mV and ≤200 mV respectively under defined test conditions, ensuring predictable performance in noisy supply environments.

Key Specifications

Pinout & Package

Supplied in TO-92 package (ECOPACK® compliant), with 3 leads: Input (pin 1), Ground (pin 2), Output (pin 3). The TO-92 outline conforms to ST's mechanical drawing per DocID2511 Rev 18 Section 5.1, with body dimensions 4.32–4.95 mm wide × 12.70–15.49 mm long and lead pitch 2.41–2.67 mm.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM7912CDT/NOPB and MC79L12ACDR2G, the L79L12ACD13TR offers optimal balance of TO-92 through-hole compatibility, lowest dropout, and industry-standard thermal protection - making it preferred for cost-sensitive, space-constrained industrial PCBs requiring proven reliability and legacy footprint support.

Availability

L79L12ACD13TR is available at Aetrix Electronics and suitable for industrial sensor nodes, RS-232 interface modules, and medical analog front-end designs requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for L79L12ACD13TR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-effective, robust local regulation in space-constrained and thermally demanding applications - emphasizing simplicity, protection, and long-term manufacturability.

FAQ

What is the maximum input voltage for L79L12ACD13TR?

The absolute maximum DC input voltage is -35 V when regulating -12 V output, per Table 1 in ST's DocID2511 Rev 18. Operation above -27 V is not recommended for continuous use due to increased power dissipation and thermal stress - design should maintain VI between -14.5 V and -27 V for optimal reliability and regulation accuracy.

Does L79L12ACD13TR require an input bypass capacitor?

Yes - ST specifies a minimum 0.33 µF ceramic capacitor between Input (pin 1) and Ground (pin 2), placed as close as possible to the device. This stabilizes the regulator under fast load transients and suppresses high-frequency noise from upstream sources, preventing oscillation or regulation error.

Can L79L12ACD13TR be used in parallel for higher current?

No - the L79L12ACD13TR lacks current-sharing features such as precision output matching or external current-sense inputs. Parallel connection risks thermal runaway due to minor output voltage mismatches; ST recommends using a single higher-current regulator (e.g., L7912) or external pass transistor instead.

Is L79L12ACD13TR compatible with lead-free soldering processes?

Yes - the TO-92 package is ECOPACK®-compliant and rated for standard lead-free reflow profiles (JEDEC J-STD-020). Peak temperature must not exceed 260 °C for ≤10 seconds, and moisture sensitivity level is MSL1 - no baking required prior to assembly.