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

STMicroelectronics L78L12ACZ-AP

Name: L78L12ACZ-AP
Brand: STMicroelectronics
SKU: L78L12ACZ-AP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L78L12ACZ-AP

Manufacturer:: STMicroelectronics

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

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

Datasheet:: L78L12ACZ-AP.pdf

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

Quantity:: RFQ Add To RFQ list

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Inventory:188

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Product details

Overview

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

For engineers reviewing the L78L12ACZ-AP datasheet, L78L12ACZ-AP pinout, L78L12ACZ-AP application, or L78L12ACZ-AP equivalent, this device serves as a drop-in replacement for Zener-diode/resistor regulators-offering lower quiescent current (6.5 mA typ.), improved line/load regulation (200 mV/50 mV max), and higher supply voltage rejection (37–42 dB).

Technical Context

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

Designed for use in TO-92 packages with through-hole mounting, it operates over 0 °C to 125 °C junction temperature and supports input voltages from 14.5 V to 27 V for reliable 12 V regulation. Dropout voltage is specified at 1.7 V, enabling operation with minimal headroom in constrained supply environments.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	12 V nominal, ±4% tolerance (11.5–12.5 V at 25 °C); ensures stable MCU core or analog sensor rail under varying load/temperature.
Output Current	Up to 100 mA continuous; sufficient for powering small logic, op-amps, or low-power microcontrollers without heatsinking.
Dropped Voltage	1.7 V typical dropout; allows operation from 13.7 V input while maintaining regulation-critical for battery-backed or margin-constrained systems.
Quiescent Current	6.5 mA at 25 °C; enables low standby power in always-on monitoring nodes where efficiency matters.
Supply Rejection	37–42 dB at 120 Hz; suppresses ripple from unregulated DC supplies or noisy switcher outputs feeding downstream analog stages.
Noise Voltage	80 µV RMS (10 Hz–100 kHz); minimizes interference in precision ADC references or audio preamp biasing.
Thermal Shutdown	Integrated junction temperature cutoff at ~165 °C; prevents catastrophic failure during sustained overload or poor PCB heat sinking.

Pinout & Package

Supplied in TO-92 package (3-pin, through-hole), with standardized pinout: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The package uses epoxy-molded plastic construction and is RoHS-compliant per ECOPACK2 specifications.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Input)	Unregulated DC input connection	Accepts 14.5–27 V DC; must be decoupled with ≥0.33 µF ceramic capacitor close to pin for stability.
Pin 2 (Ground)	Common reference node	Low-impedance return path for both input and output capacitors; critical for noise immunity and regulation accuracy.
Pin 3 (Output)	Regulated 12 V output	Delivers clean, stabilized voltage to load; requires ≥0.1 µF ceramic capacitor directly at pin for transient response.

Key Features

Feature	Design Value
No external components required	Self-contained regulation eliminates need for external pass transistors, feedback resistors, or compensation networks-reducing BOM count and layout area.
Internal thermal overload protection	Automatically disables output when die temperature exceeds safe limit (~165 °C), resuming operation after cooldown-no manual reset needed.
Short-circuit current limiting	Clamps output current to safe level (<100 mA) during fault conditions, preventing damage to regulator or upstream supply.
Low quiescent current	6.5 mA typical at 25 °C enables >10-year battery life in low-duty-cycle IoT sensors powered by coin cells or energy harvesters.
Fixed 12 V output with tight tolerance	±4% initial accuracy (A-grade) reduces need for post-regulation trimming in factory calibration of industrial I/O modules.

Applications

Industrial Sensor Interface

Microcontroller Power Rail

Use Scenario: Powering 12-bit SAR ADCs and analog front-ends in temperature/pressure transmitters.

IC Role / Device Role / Timing Role: Local voltage regulator providing clean, low-noise 12 V reference and analog supply.

Use Value: 80 µV output noise and 42 dB SVR prevent quantization errors and improve effective resolution by ≥0.5 LSB.

Use Scenario: Supplying 3.3 V or 5 V logic rails via secondary LDOs in programmable logic controllers (PLCs).

IC Role / Device Role / Timing Role: Primary fixed-voltage stage converting unregulated 24 V field bus to intermediate 12 V domain.

Use Value: 100 mA output supports multiple downstream LDOs and enables compact, modular PCB design with distributed regulation.

IoT Edge Node Power

Legacy Equipment Retrofit

Use Scenario: Battery-powered environmental monitors using LoRaWAN or NB-IoT modems.

IC Role / Device Role / Timing Role: Low-quiescent regulator sustaining real-time clock and sensor bias during deep sleep cycles.

Use Value: 6.5 mA IQ enables multi-year operation on AA alkaline cells, outperforming discrete Zener solutions by 3× runtime.

Use Scenario: Replacing obsolete 78L12 variants in aging medical diagnostic equipment service kits.

IC Role / Device Role / Timing Role: Pin-compatible upgrade offering tighter tolerance, lower noise, and integrated protection.

Use Value: Eliminates need for external fuses or thermal cutouts-reducing repair time and improving field reliability.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM78L12ACZ/NOPB	±5% output tolerance (vs. ±4%), higher quiescent current (5.5–8 mA), no guaranteed 125 °C operation.	Suitable for commercial-temp designs only; less suitable for extended-temperature industrial enclosures.	Select if cost sensitivity outweighs temp range and accuracy requirements; verify thermal derating above 70 °C.
MC78L12ACP	TO-92 package, ±5% tolerance, 100 mA rating, but higher dropout (2.0 V) and lower SVR (35 dB typical).	Marginally usable in 13.5 V input systems; may require larger input capacitor to maintain regulation under ripple.	Prefer only for legacy compatibility; avoid in new designs requiring low-noise or high-rejection performance.

Compared with LM78L12ACZ/NOPB and MC78L12ACP, the L78L12ACZ-AP delivers tighter output accuracy, superior supply rejection, and guaranteed operation up to 125 °C-making it optimal for next-generation industrial and automotive-adjacent edge devices.

Availability

L78L12ACZ-AP is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller power rails, IoT edge node power, and legacy equipment retrofit requiring stable component supply and long-term manufacturability.

Supply support for L78L12ACZ-AP 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 L78L series belongs to ST's legacy linear regulator product line, engineered specifically for cost-sensitive, space-constrained applications demanding simplicity, reliability, and broad temperature operation without external components.

FAQ

What is the maximum input voltage for L78L12ACZ-AP?

The absolute maximum DC input voltage is 35 V when the output is set to 12 V, per Table 1 of DS0424 Rev 30. For reliable continuous operation, ST recommends limiting input to ≤27 V to ensure adequate power dissipation margin and thermal stability under full 100 mA load.

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

No-it is only offered in TO-92 through-hole packaging. ST does not manufacture an SMD variant of the L78L12ACZ-AP. For surface-mount alternatives, consider the L78L12CD20TR (SO-8) or LD1086V12 (SOT-223), which differ in pinout, thermal performance, and footprint.

Does L78L12ACZ-AP 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. Omitting either degrades transient response, increases noise, and risks instability-especially under dynamic load changes.

How does thermal performance vary between TO-92 and SO-8 packages in the L78L series?

Per Table 2 of DS0424, the TO-92 package has R_thJA = 200 °C/W (no heatsink), while SO-8 achieves 55 °C/W with 6 cm² copper pour. Thus, the TO-92 version dissipates only ~0.3 W before reaching 125 °C junction under ambient 25 °C-limiting practical 100 mA use to ≤15 V input unless board-level heatsinking is added.

L78L12ACZ-AP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Cut Tape (CT)

Product Status:: Active

Output Configuration:: Positive

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 Current, Over Temperature, Short Circuit

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-92-3

L78L12ACZ-AP FAQ

1.How can I place an order for L78L12ACZ-AP through Aetrix?

Please submit a Request for Quotation (RFQ) for L78L12ACZ-AP 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 L78L12ACZ-AP reliable?

The price and inventory of L78L12ACZ-AP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78L12ACZ-AP is usually 5 days.

3.What payment methods are accepted for L78L12ACZ-AP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78L12ACZ-AP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L78L12ACZ-AP?

L78L12ACZ-AP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L78L12ACZ-AP 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 L78L12ACZ-AP?

For technical support, including L78L12ACZ-AP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78L12ACZ-AP requirements.

6.How does Aetrix verify that L78L12ACZ-AP is sourced from the original manufacturer or authorized distributors?

All L78L12ACZ-AP 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 L78L12ACZ-AP meets industry standards.

7.What is the process for return or replacement of L78L12ACZ-AP?

All L78L12ACZ-AP units undergo pre-shipment inspection (PSI). If there is an issue with L78L12ACZ-AP, 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 L78L12ACZ-AP part is unused and in its original packaging.

Return procedure for L78L12ACZ-AP:

1.Submit a request within 90 days.

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

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