STMicroelectronics L7912CV

Overview

L7912CV from STMicroelectronics is a fixed-output, three-terminal negative linear voltage regulator delivering -12 V at up to 1.5 A, featuring thermal overload protection, short-circuit protection, and output transition SOA protection. It operates with input voltages down to -35 V (for VO = -5 to -18 V), supports local on-card regulation in split-supply systems, and is widely used in industrial power supplies and analog circuitry requiring stable negative bias rails.

For engineers reviewing the L7912CV datasheet, L7912CV pinout, L7912CV application, or L7912CV equivalent, key selection considerations include dropout voltage (1.1 V @ 1 A), load regulation (±120 mV over 250–750 mA), thermal resistance (R_thJC = 5 °C/W in TO-220), output noise (200 µV RMS, 10 Hz–100 kHz), and compatibility with standard ±15 V dual-rail designs.

Technical Context

The L7912CV implements a monolithic PNP pass transistor architecture with internal current limiting, thermal shutdown, and safe operating area (SOA) protection for sustained negative output delivery. Its feedback loop maintains output stability across line (VI = -16 to -22 V) and load (IO = 5 mA to 1.5 A) variations without external compensation.

Designed for fixed-voltage operation, it accepts unregulated negative DC inputs and delivers tightly regulated -12 V outputs with ±1% initial accuracy (±120 mV at 25 °C), drift of -0.8 mV/°C, and supply voltage rejection of 54–60 dB at 120 Hz - enabling robust performance in noisy industrial environments.

Key Specifications

Pinout & Package

L7912CV is supplied in TO-220 package (standard single-gauge frame), with metal tab electrically connected to the output terminal and thermally coupled to the die for heatsink mounting.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar negative fixed-voltage regulation applications.

Compared with LM337T and MC7912CT, the L7912CV offers superior noise performance (200 µV), higher PSRR (54–60 dB), and lower quiescent current (3 mA), making it optimal for noise-sensitive analog and precision measurement applications where fixed -12 V output suffices.

Availability

L7912CV is available at Aetrix Electronics and suitable for industrial power supplies, analog signal conditioning, audio equipment biasing, and test & measurement equipment requiring stable component supply and long-term manufacturability.

Supply support for L7912CV 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 microcontrollers, power management ICs, analog chips, and discrete components for industrial, automotive, and consumer markets.

The L79xxC series belongs to ST's legacy linear regulator product line, engineered specifically for robust, cost-effective fixed negative voltage regulation in industrial and general-purpose analog systems - emphasizing reliability, thermal resilience, and ease of use without external components.

FAQ

What is the maximum input voltage for L7912CV?

The absolute maximum DC input voltage is -35 V when regulating -12 V output, per STMicroelectronics' datasheet (Doc ID 2149 Rev 21, Table 2). Operation above this risks permanent damage. For reliable long-term use, ST recommends limiting VI to ≤ -22 V under full load to maintain thermal margin and ensure SOA compliance.

Does L7912CV require input and output capacitors?

Yes - a 2.2 µF solid tantalum capacitor (CI) is required at the input if the regulator is located far from the bulk filter, and a 1 µF capacitor (CO) is mandatory at the output for stability. Aluminum electrolytic types may be substituted only with ≥10× capacitance value, per Figure 4 and footnote 2 in the datasheet.

Can L7912CV be used in parallel for higher current?

No - the L7912CV lacks built-in current-sharing capability. Parallel connection without external ballasting resistors causes unequal current distribution and thermal runaway. For >1.5 A, ST recommends using the L7912CD2T-TR in D²PAK (with lower R_thJA) or implementing an external high-current negative regulator stage as shown in Figure 7.

Is the metal tab on the TO-220 package electrically connected?

Yes - the metal tab is internally connected to the OUTPUT (OUT) pin. This is confirmed in ST's mechanical drawings (Figure 8, Doc ID 2149 Rev 21) and must be considered during heatsink mounting: electrical isolation (e.g., mica washer + nylon screw) is required if the heatsink is grounded or referenced to a different potential.