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STMicroelectronics L79L12ACZ-TR
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- Part No.:
- L79L12ACZ-TR
- Manufacturer:
- STMicroelectronics
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
L79L12ACZ-TR.pdf
- Description:
- IC REG LINEAR -12V 100MA TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:1,357
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Product details
Overview
L79L12ACZ-TR 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 optimized for local on-card regulation in industrial control, sensor signal conditioning, and legacy analog power rails where low-noise, stable negative bias is critical.
For engineers reviewing the L79L12ACZ-TR datasheet, L79L12ACZ-TR pinout, L79L12ACZ-TR application, or L79L12ACZ-TR equivalent, this page provides verified electrical characteristics, TO-92 package details, thermal performance data, noise and rejection metrics, and validated alternative options for design-in and supply continuity.
Technical Context
The L79L12ACZ-TR operates as a monolithic PNP-based linear regulator with fixed -12 V output, designed for input voltages between -14.5 V and -27 V. Its architecture integrates thermal shutdown and foldback current limiting, eliminating need for external protection circuitry.
It achieves 80 µV RMS output noise (10 Hz–100 kHz), 42 dB supply voltage rejection at 120 Hz, and maintains ±5% output accuracy over temperature (0 °C to 125 °C junction) and load (1–100 mA). Dropout voltage is fixed at 1.7 V under full load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | -12 V ±5% (min -11.4 V, max -12.6 V at 1–40 mA, TJ = 25 °C) |
| Output Current | 100 mA maximum continuous - supports small-signal analog stages and logic biasing |
| Dropout Voltage | 1.7 V - defines minimum VI–VO differential required for regulation |
| Output Noise | 80 µV RMS (10 Hz–100 kHz) - enables use in precision op-amp and ADC reference rails |
| Supply Rejection | 37–42 dB at 120 Hz - suppresses ripple from unregulated DC supplies or rectified AC |
| Quiescent Current | 6.5 mA at 25 °C - low static draw suitable for battery-backed or standby circuits |
| Thermal Shutdown | Active above 150 °C junction - prevents damage during sustained overload or poor heatsinking |
Pinout & Package
Supplied in TO-92 plastic package (ECOPACK® compliant), with 3.3 mm pitch, 4.95 mm max height, and integrated heat-dissipating lead frame. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output (viewed from flat side, leads down).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (Input) | Unregulated negative input supply | Accepts -14.5 V to -27 V; must be ≥1.7 V more negative than output to sustain regulation |
| Pin 2 (Ground) | Common reference node | Shared return path for input and output; must be low-impedance to minimize noise coupling |
| Pin 3 (Output) | Regulated -12 V output | Delivers stable bias to downstream analog ICs; decoupling capacitor (0.1 µF) required per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| No external components required | Eliminates need for external pass transistor, compensation network, or protection diodes |
| Internal thermal overload protection | Automatically disables output above ~150 °C junction, resuming operation after cooldown |
| Short-circuit current limiting | Foldback behavior limits output current to ~150 mA during hard shorts, reducing power dissipation |
| Low output impedance vs Zener replacement | ~100× lower effective output impedance than -12 V Zener/resistor solution, improving load regulation |
| Low quiescent current | 6.5 mA typical at 25 °C - reduces system-level standby power in dual-rail supplies |
Applications
| Industrial Sensor Signal Conditioning | Legacy Analog Instrumentation |
|---|---|
|
Use Scenario: Providing clean -12 V bias to op-amps and instrumentation amplifiers in 4–20 mA transmitter modules. IC Role / Device Role / Timing Role: Fixed negative rail generator enabling bipolar signal swing and common-mode rejection. Use Value: 80 µV noise and 42 dB SVR prevent supply-induced offset drift in µV-level measurements. |
Use Scenario: Powering vintage analog panel meters, potentiometric controllers, and analog PID circuits. IC Role / Device Role / Timing Role: Replacement for discrete Zener/resistor networks in aging equipment service kits. Use Value: ±5% tolerance and thermal stability eliminate recalibration when upgrading legacy power sections. |
| Embedded Microcontroller Analog Peripherals | Audio Pre-amplifier Bias Rails |
|
Use Scenario: Supplying -12 V to ADC reference buffers and DAC output stages in ARM Cortex-M based data loggers. IC Role / Device Role / Timing Role: Local regulation isolating analog subsystems from noisy digital supply domains. Use Value: 100 mA capability supports multiple parallel analog channels without cross-talk via shared rail. |
Use Scenario: Generating symmetrical ±12 V rails for discrete JFET-input pre-amplifiers in studio-grade audio interfaces. IC Role / Device Role / Timing Role: Low-noise negative rail source minimizing hiss and hum in high-gain analog front-ends. Use Value: 80 µV RMS noise ensures SNR > 100 dB in 20 Hz–20 kHz audio band without additional filtering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed negative voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM7912CDT/NOPB | TO-220 package; higher 1.5 A rating; 2.5 V dropout; 100 µV noise | Requires heatsink above ~150 mW; suited for higher-current analog rails | Select when >100 mA load or better thermal margin is needed; not drop-in due to footprint and pinout |
| MC79L12ACPRMG | SOT-89 package; same 100 mA rating; 1.7 V dropout; 90 µV noise | Smaller footprint; higher RthJA (115 °C/W); limited PCB copper area for heatsinking | Select for space-constrained PCBs where TO-92 mounting is impractical; verify thermal derating |
Compared with LM7912CDT/NOPB, L79L12ACZ-TR offers lower cost and simpler layout but less current headroom; versus MC79L12ACPRMG, it delivers identical regulation specs with superior thermal performance in TO-92 due to lower RthJA (200 °C/W vs 115 °C/W) when using standard board copper.
Availability
L79L12ACZ-TR is available at Aetrix Electronics and suitable for industrial sensor nodes, analog instrumentation upgrades, and embedded microcontroller peripheral biasing requiring stable component supply across multi-year production cycles.
Supply support for L79L12ACZ-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, MCU, power, and sensing solutions for industrial, automotive, and consumer markets.
The L79L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, low-to-medium current fixed-voltage applications where reliability, simplicity, and long-term availability are prioritized over programmability or ultra-low quiescent current.
FAQ
What is the minimum input voltage required for regulation with L79L12ACZ-TR?
The absolute minimum input voltage is -14.5 V under specified test conditions (IO = 1–40 mA, TJ = 25 °C). At full 100 mA load, input must be ≤ -13.7 V to maintain regulation, as dropout voltage remains fixed at 1.7 V. Below this threshold, output voltage collapses linearly with input.
Can L79L12ACZ-TR be used in parallel to increase output current?
No - the L79L12ACZ-TR lacks current-sharing features and has no built-in balancing circuitry. Parallel connection risks thermal runaway due to mismatched output voltages and thermal coefficients. For higher current, use a single higher-rated regulator like LM7912 or add an external pass transistor with proper biasing.
Does L79L12ACZ-TR require input and output capacitors?
Yes: a 0.33 µF ceramic input capacitor (CI) and 0.1 µF ceramic output capacitor (CO) are mandatory per ST's test circuit and recommended layout. Omitting either degrades transient response, increases noise, and may cause oscillation or thermal instability under dynamic load changes.
Is L79L12ACZ-TR RoHS-compliant and halogen-free?
Yes - the L79L12ACZ-TR is manufactured in ST's ECOPACK®-compliant TO-92 package, meeting RoHS Directive 2011/65/EU and halogen-free requirements per IEC 61249-2-21. Full compliance documentation is available in ST's official product change notices and material declarations.
L79L12ACZ-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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-TR FAQ
1.How can I place an order for L79L12ACZ-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for L79L12ACZ-TR 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-TR reliable?
The price and inventory of L79L12ACZ-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L79L12ACZ-TR is usually 5 days.
3.What payment methods are accepted for L79L12ACZ-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L79L12ACZ-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L79L12ACZ-TR?
L79L12ACZ-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L79L12ACZ-TR 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-TR?
For technical support, including L79L12ACZ-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L79L12ACZ-TR requirements.
6.How does Aetrix verify that L79L12ACZ-TR is sourced from the original manufacturer or authorized distributors?
All L79L12ACZ-TR 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-TR meets industry standards.
7.What is the process for return or replacement of L79L12ACZ-TR?
All L79L12ACZ-TR units undergo pre-shipment inspection (PSI). If there is an issue with L79L12ACZ-TR, 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-TR part is unused and in its original packaging.
Return procedure for L79L12ACZ-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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