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

STMicroelectronics L78L08ACD

Name: L78L08ACD
Brand: STMicroelectronics
SKU: L78L08ACD
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L78L08ACD

Manufacturer:: STMicroelectronics

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

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: L78L08ACD.pdf

Description:: IC REG LINEAR 8V 100MA 8SO

Quantity:: RFQ Add To RFQ list

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Inventory:2,485

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Product details

Overview

L78L08ACD from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 8 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 rated for operation from 0 °C to 125 °C junction temperature, commonly used for local on-card regulation in microcontroller power rails and sensor interface circuits.

For engineers reviewing the L78L08ACD datasheet, L78L08ACD pinout, L78L08ACD application, or L78L08ACD equivalent, this page provides verified technical context, package-specific design meaning, real-world use scenarios, and validated alternative options for low-power fixed-voltage regulation.

Technical Context

The L78L08ACD implements a monolithic series pass transistor with built-in thermal shutdown and foldback current limiting, eliminating need for external protection circuitry. Its dropout voltage is fixed at 1.7 V across load and temperature, enabling stable regulation when input exceeds 9.7 V under full 100 mA load.

It operates without external capacitors for basic functionality but specifies 0.33 µF input and 0.1 µF output ceramic capacitors for optimal transient response and noise suppression. Output noise is 60 µV RMS (10 Hz–100 kHz), and supply voltage rejection reaches 45 dB at 120 Hz with 12–23 V input range.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	8 V ±4% (7.68–8.32 V at 25 °C); ensures compatibility with 8 V logic or analog subsystems requiring tight tolerance.
Max Output Current	100 mA; sufficient for powering small MCUs, sensors, or op-amps without heatsinking in TO-92.
Dropout Voltage	1.7 V; defines minimum VI–VO differential needed to maintain regulation-e.g., 9.7 V min input at 100 mA load.
Quiescent Current	6 mA at 25 °C; enables predictable bias consumption in battery-backed or low-duty-cycle systems.
Output Noise	60 µV RMS (10 Hz–100 kHz); supports noise-sensitive analog stages like ADC references or audio preamps.
SVR @ 120 Hz	37–45 dB; suppresses ripple from rectified AC supplies or switching converter post-regulation.
Thermal Shutdown	Active above ~150 °C junction; prevents damage during sustained overload or poor PCB copper layout.

Pinout & Package

Supplied in TO-92 package (JEDEC TO-226AA), with molded plastic case, axial leads, and through-hole mounting. Thermal resistance junction-to-ambient is 200 °C/W (no heatsink), limiting continuous 100 mA operation to ambient ≤55 °C without PCB copper area.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1	VOUT	Regulated 8 V output; connects directly to load and local bypass capacitor (0.1 µF).
Pin 2	GND	Ground reference for both regulator control and load return path; must be low-impedance.
Pin 3	VIN	Unregulated DC input; must exceed 9.7 V under max load to sustain regulation; decoupled with 0.33 µF.

Key Features

Feature	Design Value
No external components required	Enables single-device local regulation-reduces BOM count and board space vs. discrete Zener/resistor solutions.
Internal thermal shutdown	Automatically disables output above safe junction temperature, eliminating need for external thermal monitoring.
Short-circuit protection	Current foldback limits fault current to <50 mA during output short, preventing trace fusing or PCB damage.
±4% output tolerance (A grade)	Meets tighter spec than C-grade (±8%), suitable for applications where 8 V rail accuracy impacts ADC LSB or comparator thresholds.
Low quiescent current	6 mA typical enables >1000 h runtime on 600 mAh batteries in always-on sensor nodes.

Applications

Industrial Sensor Node Power

Microcontroller Core Supply

Use Scenario: Powering a 3.3 V MCU with integrated 8 V analog front-end (e.g., op-amp bias, DAC reference).

IC Role / Device Role / Timing Role: Fixed 8 V local regulator supplying analog subsystem; decoupled from noisy digital rail.

Use Value: Eliminates noise coupling from digital switching while maintaining 8 V accuracy within ±4% for precision analog functions.

Use Scenario: Providing clean 8 V to external peripherals (e.g., EEPROM, RTC, level-shifter ICs) on an embedded control board.

IC Role / Device Role / Timing Role: Dedicated low-noise auxiliary supply; isolated from main 5 V/3.3 V domains.

Use Value: Reduces cross-talk-induced timing jitter in I²C/SPI communication lines connected to 8 V-tolerant devices.

Legacy Equipment Retrofit

Portable Medical Instrument

Use Scenario: Replacing aging 7808-style regulators in field-deployed PLC I/O modules with higher reliability demand.

IC Role / Device Role / Timing Role: Drop-in replacement for obsolete 8 V linear regulators; same pinout and footprint.

Use Value: Delivers improved thermal robustness and lower quiescent current versus legacy bipolar 78xx parts.

Use Scenario: Supplying 8 V to piezoelectric transducer driver circuitry in handheld ultrasound probe assemblies.

IC Role / Device Role / Timing Role: Low-noise analog supply enabling clean excitation pulses with minimal baseline drift.

Use Value: 60 µV output noise and 45 dB SVR ensure transducer signal integrity during echo reception phase.

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
MC78L08ACP	Same 8 V output, ±5% tolerance, 100 mA rating; TO-92 package; quiescent current 3.8 mA (lower), dropout 1.7 V.	Lower IQ benefits battery life; slightly looser output tolerance may affect precision analog stages.	Select when minimizing standby power is critical and 8 V ±5% is acceptable for target load.
LM78L08ACZ	8 V output, ±5% tolerance, 100 mA; TO-92; quiescent current 5.5 mA; dropout 1.7 V; SVR 40 dB @ 120 Hz.	Higher noise (80 µV) and lower SVR than L78L08ACD; identical thermal protection architecture.	Choose if sourcing flexibility is prioritized and system-level noise budget allows 20 µV higher RMS noise.

Compared with MC78L08ACP and LM78L08ACZ, the L78L08ACD offers tighter ±4% output tolerance and lower 60 µV noise-advantageous for precision analog or low-jitter timing applications-while trading off slightly higher quiescent current than the MC78L08ACP.

Availability

L78L08ACD is available at Aetrix Electronics and suitable for industrial sensor nodes, microcontroller auxiliary supplies, legacy equipment retrofits, and portable medical instruments requiring stable component supply across multi-year production cycles.

Supply support for L78L08ACD 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, 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 for cost-effective, robust local voltage regulation in space-constrained and thermally challenging environments-especially where simplicity, reliability, and long-term availability are critical.

FAQ

What is the minimum input voltage required for L78L08ACD to regulate at full 100 mA?

The dropout voltage is specified as 1.7 V. To maintain 8 V output at 100 mA, the input must be ≥9.7 V. At lower inputs-e.g., 9.0 V-the output will drop below 8 V and regulation is lost. This value holds across the full operating temperature range (0–125 °C).

Can L78L08ACD be used with ceramic output capacitors?

Yes-ST specifies 0.1 µF ceramic (X7R or better) for CO. Unlike older 78xx regulators, the L78L series is stable with low-ESR ceramics and does not require tantalum or aluminum electrolytic capacitors. Input capacitor CI = 0.33 µF ceramic is also recommended.

Does L78L08ACD include reverse-polarity protection?

No. The device lacks internal reverse-voltage protection. If VIN can be accidentally reversed (e.g., during board assembly or field maintenance), an external series diode or MOSFET-based protection circuit is required to prevent destruction.

How does thermal performance differ between TO-92 and SO-8 packages for L78L08ACD?

In TO-92, R_thJA is 200 °C/W (no heatsink), limiting 100 mA operation to ≤55 °C ambient. In SO-8, R_thJA drops to 55 °C/W with 6 cm² PCB copper, allowing full 100 mA at up to 95 °C ambient-making SO-8 preferable for high-density or elevated-temperature deployments.

L78L08ACD Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tube

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 30V

Voltage - Output (Min/Fixed):: 8V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

Current - Output:: 100mA

Current - Quiescent (Iq):: 5.5 mA

Current - Supply (Max):: 6 mA

PSRR:: 45dB (120Hz)

Control Features:: -

Protection Features:: Over Current, Over Temperature, Short Circuit

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

L78L08ACD FAQ

1.How can I place an order for L78L08ACD through Aetrix?

Please submit a Request for Quotation (RFQ) for L78L08ACD 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 L78L08ACD reliable?

The price and inventory of L78L08ACD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78L08ACD is usually 5 days.

3.What payment methods are accepted for L78L08ACD?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78L08ACD transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L78L08ACD?

L78L08ACD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L78L08ACD 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 L78L08ACD?

For technical support, including L78L08ACD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78L08ACD requirements.

6.How does Aetrix verify that L78L08ACD is sourced from the original manufacturer or authorized distributors?

All L78L08ACD 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 L78L08ACD meets industry standards.

7.What is the process for return or replacement of L78L08ACD?

All L78L08ACD units undergo pre-shipment inspection (PSI). If there is an issue with L78L08ACD, 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 L78L08ACD part is unused and in its original packaging.

Return procedure for L78L08ACD:

1.Submit a request within 90 days.

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

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