Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

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

STMicroelectronics L78L05ACZ

Name: L78L05ACZ
Brand: STMicroelectronics
SKU: L78L05ACZ
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: L78L05ACZ

Manufacturer:: STMicroelectronics

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

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

Datasheet:: L78L05ACZ.pdf

Description:: IC REG LINEAR 5V 100MA TO92-3

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:3,513

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

L78L05ACZ from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 5 V output at up to 100 mA, featuring internal current limiting, thermal overload protection, and short-circuit protection. It requires no external components, operates with input voltages up to 30 V (for 5 V output), and maintains ±4% output tolerance over 0–125 °C junction temperature. It is used for local on-card regulation in microcontroller power domains, sensor interface rails, and low-power industrial control modules.

For engineers reviewing the L78L05ACZ datasheet, L78L05ACZ pinout, L78L05ACZ application, or L78L05ACZ equivalent, this device serves as a drop-in replacement for legacy 78L05 regulators where low quiescent current (6 mA typ.), low noise (40 µV RMS), and robust thermal shutdown are critical in space-constrained PCBs using TO-92 packaging.

Technical Context

The L78L05ACZ implements a monolithic series pass transistor architecture with built-in foldback current limiting and thermal shutdown circuitry, enabling self-protection without external sensing components. Its internal bandgap reference and error amplifier maintain stable 5 V regulation across load currents from 1 mA to 100 mA and input voltages from 7 V to 20 V.

It exhibits 100 mV line regulation (VI = 8–20 V) and 30 mV load regulation (IO = 1–40 mA) at 25 °C, with 41–49 dB supply voltage rejection at 120 Hz. Dropout voltage is specified at 2 V, requiring minimum VI ≥ 7 V for full-load operation.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	5.0 V ±4% (4.8–5.2 V at 25 °C); ensures compatibility with 5 V TTL/CMOS logic and MCU I/O rails.
Max Output Current	100 mA; sufficient for powering small microcontrollers, sensors, or logic ICs without heatsinking.
Input Voltage Range	7–20 V DC; supports common 9 V and 12 V supply rails while maintaining regulation.
Droput Voltage	2 V; requires minimum 7 V input to sustain 5 V/100 mA output under worst-case conditions.
Quiescent Current	6 mA typical at 25 °C; enables low standby power in battery-backed or energy-sensitive systems.
Output Noise	40 µV RMS (10 Hz–100 kHz); suitable for analog signal chains and precision ADC reference supplies.
Thermal Shutdown	Activates at ~150 °C junction temperature; prevents damage during sustained overload or poor PCB thermal design.

Pinout & Package

Supplied in TO-92 package (3-lead plastic transistor outline), with leads arranged vertically when viewed from bottom: Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The package provides adequate thermal dissipation for ≤100 mA loads with minimal copper area.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Left)	Input (VI)	Accepts unregulated DC input; must be decoupled with ≥0.33 µF ceramic capacitor close to pin.
Pin 2 (Center)	Ground (GND)	Common return path for input and output; connects internally to die substrate and case tab.
Pin 3 (Right)	Output (VO)	Delivers regulated 5 V; requires ≥0.1 µF ceramic output capacitor for stability and transient response.

Key Features

Feature	Design Value
No external components required	Internal compensation and biasing eliminate need for external capacitors beyond mandatory input/output bypassing.
Thermal overload protection	Automatic shutdown at ~150 °C junction temperature; resumes operation after cooldown without latch-up.
Short-circuit protection	Foldback current limiting reduces output current to <100 mA during output-to-ground fault, preventing destruction.
Low output noise	40 µV RMS noise floor enables use in analog front-ends and precision reference applications without added filtering.
±4% output tolerance	Tighter initial accuracy than standard C-grade (±8%), improving system margin for 5 V logic and ADC references.

Applications

Industrial Sensor Node Power

Microcontroller Core Rail

Use Scenario: Powering analog temperature/humidity sensors and low-speed UART transceivers in factory-floor monitoring nodes.

IC Role / Device Role / Timing Role: Local point-of-load regulator providing clean, stable 5 V from a shared 12 V backplane.

Use Value: Eliminates noise coupling from switching supplies and avoids voltage droop during sensor burst-read cycles.

Use Scenario: Supplying VDD for 8-bit MCUs (e.g., STM8, PIC16) in cost-sensitive embedded controllers.

IC Role / Device Role / Timing Role: Primary 5 V rail generator with fast transient response to handle core clock domain switching events.

Use Value: Ensures reset integrity and flash programming stability under varying code execution loads up to 100 mA peak.

Legacy Equipment Replacement

IoT Edge Device Bias Supply

Use Scenario: Direct replacement for obsolete 78L05 variants in field-deployed PLC I/O modules requiring long-term component continuity.

IC Role / Device Role / Timing Role: Pin- and footprint-compatible upgrade offering improved thermal robustness and tighter output tolerance.

Use Value: Extends service life of aging hardware without PCB redesign or firmware changes.

Use Scenario: Generating auxiliary 5 V bias for RF front-end ICs and EEPROMs in battery-operated smart meters.

IC Role / Device Role / Timing Role: Low-quiescent-current regulator minimizing sleep-mode leakage while supporting wake-on-event functionality.

Use Value: Reduces average system current by >1 mA versus older 78L05 designs, extending battery life by months.

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
LM78L05ACZ	±5% output tolerance (vs. ±4%), higher quiescent current (5.5–8 mA), no guaranteed 125 °C operation.	Suitable for commercial-temperature-only designs; lacks extended temp grade certification.	Select if operating ambient stays below 70 °C and ±5% output accuracy is acceptable.
MC78L05ACP	TO-92 package, ±5% tolerance, 100 mA rating, but higher dropout (2.5 V) and lower SVR (35–42 dB).	Compatible in footprint but degrades noise immunity and efficiency in low-input-voltage scenarios.	Prefer only when LM78L05ACZ is unavailable and board layout cannot accommodate revised thermal or noise margins.

Compared with LM78L05ACZ and MC78L05ACP, the L78L05ACZ delivers tighter output tolerance, superior supply rejection, and guaranteed operation up to 125 °C - making it the optimal choice for industrial and automotive-adjacent applications demanding reliability and precision without design compromise.

Availability

L78L05ACZ is available at Aetrix Electronics and suitable for industrial sensor nodes, microcontroller power domains, legacy equipment replacement programs, and IoT edge device bias supplies requiring stable component supply across multi-year production cycles.

Supply support for L78L05ACZ 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, microcontroller, power, and sensor 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 requiring ruggedness, simplicity, and long-term availability - not programmability or digital interface.

FAQ

What is the minimum input voltage required for L78L05ACZ to regulate at full 100 mA load?

The dropout voltage is 2 V, and the output must remain ≥4.8 V (–4% tolerance). Therefore, minimum input is 4.8 V + 2 V = 6.8 V. However, per datasheet test conditions and derating, 7 V is the validated minimum for reliable 100 mA operation across temperature and process variation.

Can L78L05ACZ be used in parallel to increase output current?

No - the L78L05ACZ lacks current-sharing capability and has no built-in balancing features. Parallel connection risks thermal runaway due to mismatched output voltages and unequal current distribution; external ballast resistors are not recommended and void thermal protection guarantees.

Is an input capacitor mandatory, and what value is recommended?

Yes - a minimum 0.33 µF ceramic capacitor placed within 1 cm of the input pin is mandatory for high-frequency stability and to prevent oscillation. Larger values (e.g., 1–10 µF tantalum) improve low-frequency ripple rejection but do not replace the ceramic requirement.

Does L78L05ACZ support reverse-input protection?

No - the device lacks internal reverse-polarity protection. Applying negative voltage to the input pin relative to ground can cause irreversible damage. An external series diode (e.g., 1N4001) is required if reverse input is possible in the system.

L78L05ACZ Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Bulk

Product Status:: Active

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 30V

Voltage - Output (Min/Fixed):: 5V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

Current - Output:: 100mA

Current - Quiescent (Iq):: 5.5 mA

Current - Supply (Max):: 6 mA

PSRR:: 49dB (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

L78L05ACZ FAQ

1.How can I place an order for L78L05ACZ through Aetrix?

Please submit a Request for Quotation (RFQ) for L78L05ACZ 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 L78L05ACZ reliable?

The price and inventory of L78L05ACZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78L05ACZ is usually 5 days.

3.What payment methods are accepted for L78L05ACZ?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78L05ACZ transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L78L05ACZ?

L78L05ACZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L78L05ACZ 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 L78L05ACZ?

For technical support, including L78L05ACZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78L05ACZ requirements.

6.How does Aetrix verify that L78L05ACZ is sourced from the original manufacturer or authorized distributors?

All L78L05ACZ 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 L78L05ACZ meets industry standards.

7.What is the process for return or replacement of L78L05ACZ?

All L78L05ACZ units undergo pre-shipment inspection (PSI). If there is an issue with L78L05ACZ, 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 L78L05ACZ part is unused and in its original packaging.

Return procedure for L78L05ACZ:

1.Submit a request within 90 days.

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

Tech Hub

2026-09-11 Comparator Circuit: Voltage Thresholds, Op-Amp Differences, LM393 and Practical Design

Comparator circuit design covering voltage thresholds, input limits, open-collector outputs, LM393 wiring, op-amp differences, hysteresis, timing, window detection and practical fault diagnosis.

2026-09-10 Schmitt Trigger Explained: Hysteresis, Circuits, Inverters and Applications

Schmitt triggers use separate rising and falling thresholds to stabilize slow or noisy signals. This guide covers hysteresis, 74HC14 and 74HCT14 selection, comparator calculations, RC oscillators and p…

2026-09-09 Counterfeit Electronic Components: How to Detect, Authenticate, and Test Suspect Parts

Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …

2026-09-08 Obsolete Electronic Components: How to Source and Evaluate Replacements

A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …