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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

STMicroelectronics L79L12ACZ

Name: L79L12ACZ
Brand: STMicroelectronics
SKU: L79L12ACZ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L79L12ACZ

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: TO-226-3, TO-92-3 (TO-226AA)

Datasheet:: L79L12ACZ.pdf

Description:: IC REG LINEAR -12V 100MA TO92-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,895

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Product details

Overview

L79L12ACZ from STMicroelectronics is a three-terminal fixed negative voltage regulator delivering -12 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components and is designed for local on-card regulation in industrial control, embedded power supplies, and noise-sensitive analog subsystems.

For engineers reviewing the L79L12ACZ datasheet, L79L12ACZ pinout, L79L12ACZ application, or L79L12ACZ equivalent, key selection criteria include its ±5% output tolerance (AC grade), 1.7 V dropout voltage, 80 µV RMS output noise, 42 dB supply voltage rejection at 120 Hz, and TO-92 package thermal performance with R_thj-amb = 200 °C/W.

Technical Context

The L79L12ACZ implements a monolithic bipolar linear regulator architecture with built-in thermal shutdown and foldback current limiting. Its internal reference and error amplifier maintain stable -12 V output across input voltages from -14.5 V to -27 V and load currents from 1 mA to 100 mA.

It operates over an extended temperature range of 0 to 125 °C (junction), supports capacitor-stabilized operation with 0.33 µF input and 0.1 µF output ceramic capacitors, and achieves 100 mV load regulation (1–100 mA) and 250 mV line regulation (-14.5 to -27 V) at 25 °C.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	-12 V nominal, ±5% tolerance (±0.6 V) at 25 °C ensures compatibility with -12 V logic and analog rails
Max Output Current	100 mA continuous - sufficient for low-power microcontrollers, op-amps, and sensor interfaces
Dropout Voltage	1.7 V - enables operation with input as low as -13.7 V while maintaining regulation
Output Noise	80 µV RMS (10 Hz–100 kHz) - suitable for precision analog circuitry without added filtering
SVR @ 120 Hz	37–42 dB - suppresses ripple from rectified AC sources in linear power supplies
Quiescent Current	6.5 mA at 25 °C - balances low-noise performance with standby power efficiency
Thermal Resistance	R_thj-amb = 200 °C/W (TO-92) - requires minimal PCB copper area for safe 100 mA operation

Pinout & Package

Package: TO-92 (3-lead plastic transistor outline), lead material: matte tin, RoHS-compliant, JEDEC registered outline.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	GND	Reference node for output voltage; connects to system ground plane for stability and noise control
Pin 2	VIN	Negative input terminal; accepts unregulated DC input down to -27 V (absolute max -35 V)
Pin 3	VOUT	Regulated -12 V output; must be decoupled with ≥0.1 µF ceramic capacitor near the pin

Key Features

Feature	Design Value
No external components required	Integrated pass element, reference, and error amplifier eliminate need for external resistors or capacitors beyond basic bypassing
Thermal overload protection	Automatic shutdown below 150 °C junction temperature prevents damage during sustained overload or poor heatsinking
Short-circuit protection	Foldback current limiting reduces power dissipation during output shorts, enabling indefinite fault survival
Low output impedance	~10× lower effective output impedance vs. Zener/resistor regulators - improves transient response and PSRR
Wide input voltage range	Supports -14.5 V to -27 V input - accommodates transformer-based supplies with ±10% line variation and ripple

Applications

Industrial Sensor Interface

Legacy RS-232 Transceiver Supply

Use Scenario: Powering analog front-end circuits for 4–20 mA loop-powered sensors in PLC I/O modules.

IC Role / Device Role / Timing Role: Local negative rail generator providing clean, isolated -12 V for op-amp bias and ADC reference buffers.

Use Value: Eliminates noise coupling from shared system ground and improves common-mode rejection by >40 dB versus single-point regulation.

Use Scenario: Generating -12 V supply for MAX232 or similar dual-supply RS-232 level shifters in industrial gateways.

IC Role / Device Role / Timing Role: Fixed negative voltage source enabling compliant ±12 V driver outputs per EIA-232 standard.

Use Value: Maintains guaranteed driver swing under full load (±10 mA) with <100 mV load regulation, ensuring robust serial communication.

Analog Audio Signal Conditioning

Embedded Microcontroller Auxiliary Rail

Use Scenario: Providing symmetrical ±12 V rails for audio op-amps in portable test equipment preamplifiers.

IC Role / Device Role / Timing Role: Low-noise negative regulator paired with L78L12ACZ to form split supply for rail-to-rail signal processing.

Use Value: 80 µV RMS noise and 42 dB SVR prevent audible hum and preserve SNR >95 dB in 24-bit audio paths.

Use Scenario: Supplying -12 V to external DACs, EEPROM programmers, or debug interface circuitry in ARM Cortex-M based edge controllers.

IC Role / Device Role / Timing Role: Dedicated auxiliary regulator for peripherals requiring negative bias or level-shifting not supported by main PMIC.

Use Value: Enables reliable in-system programming and calibration functions without modifying primary 3.3 V/5 V power architecture.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM7912ACZ	Same -12 V output, ±5% tolerance, but higher quiescent current (6.5 mA vs. 6.5 mA typical), slightly lower SVR (35 dB), and TO-220 package option	Requires larger PCB footprint and external heatsink above ~50 mA; less suitable for space-constrained designs	Prefer when higher power dissipation (>0.5 W) or legacy LM79 pinout compatibility is required
MC79L12ACPRPG	Identical electrical specs and TO-92 package, but rated for -40 to 125 °C (AB grade) and manufactured by ON Semiconductor	Validated for automotive under-hood use where extended temperature range is mandatory	Choose when AEC-Q100 qualification or wider operating temperature is needed beyond ST's AC grade (0–125 °C)

Compared with LM7912ACZ, L79L12ACZ offers superior thermal performance in TO-92 and lower noise; compared with MC79L12ACPRPG, it trades extended temperature range for tighter initial tolerance and ST-specific reliability screening in industrial applications.

Availability

L79L12ACZ is available at Aetrix Electronics and suitable for industrial sensor interfaces, RS-232 transceiver supplies, and analog audio signal conditioning requiring stable component supply, long-term obsolescence management, and traceable lot-level documentation.

Supply support for L79L12ACZ 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 silicon solutions for automotive, industrial, and consumer markets since 1987.

The L79Lxx series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications demanding high reliability, integrated protection, and minimal external components in industrial and embedded systems.

FAQ

What is the minimum input voltage required for L79L12ACZ to maintain regulation?

The L79L12ACZ requires a minimum input voltage of -13.7 V to sustain -12 V output at full 100 mA load, based on its 1.7 V dropout specification. At lighter loads (<10 mA), regulation holds down to -12.5 V input. Input below -35 V absolute maximum risks permanent damage.

Can L79L12ACZ be used in parallel to increase output current?

No - L79L12ACZ lacks current-sharing capability and should not be paralleled. Its internal current limiting and thermal protection are designed for single-device operation. To deliver >100 mA, use an external pass transistor with proper biasing, as documented in ST Application Note AN1052.

Is a heat sink required for continuous 100 mA operation in TO-92?

A dedicated heat sink is not required, but ≥6 cm² of 1-oz copper pour connected to Pin 1 (GND) is essential. With that, junction temperature stays below 125 °C at 25 °C ambient. Without copper area, power dissipation exceeds safe limits above ~30 mA.

How does the AC grade differ from the C grade in L79L12ACZ?

The "AC" suffix denotes ±5% output voltage tolerance at 25 °C and operation from 0 to 125 °C junction temperature. The "C" suffix indicates ±10% tolerance and same temperature range. L79L12ACZ is not rated for -40 °C operation - for that, select the AB grade (e.g., L79L12ABZ).

L79L12ACZ Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-226-3, TO-92-3 (TO-226AA)

Packaging:: Bulk

Product Status:: Obsolete

Output Configuration:: Negative

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: -35V

Voltage - Output (Min/Fixed):: -12V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

Current - Output:: 100mA

Current - Quiescent (Iq):: 6 mA

Current - Supply (Max):: 6.5 mA

PSRR:: 42dB (120Hz)

Control Features:: -

Protection Features:: Over Temperature, Short Circuit

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

L79L12ACZ FAQ

1.How can I place an order for L79L12ACZ through Aetrix?

Please submit a Request for Quotation (RFQ) for L79L12ACZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for L79L12ACZ reliable?

The price and inventory of L79L12ACZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L79L12ACZ is usually 5 days.

3.What payment methods are accepted for L79L12ACZ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L79L12ACZ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L79L12ACZ?

L79L12ACZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L79L12ACZ order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for L79L12ACZ?

For technical support, including L79L12ACZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L79L12ACZ requirements.

6.How does Aetrix verify that L79L12ACZ is sourced from the original manufacturer or authorized distributors?

All L79L12ACZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that L79L12ACZ meets industry standards.

7.What is the process for return or replacement of L79L12ACZ?

All L79L12ACZ units undergo pre-shipment inspection (PSI). If there is an issue with L79L12ACZ, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The L79L12ACZ part is unused and in its original packaging.

Return procedure for L79L12ACZ:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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