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

STMicroelectronics L78M09ABV

Name: L78M09ABV
Brand: STMicroelectronics
SKU: L78M09ABV
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L78M09ABV

Manufacturer:: STMicroelectronics

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

Package:: TO-220-3

Datasheet:: L78M09ABV.pdf

Description:: IC REG LINEAR 9V 500MA TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:2,105

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Product details

Overview

L78M09ABV from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 9 V output at up to 500 mA, featuring ±2 % output voltage tolerance, thermal overload protection, short-circuit protection, and safe operating area (SOA) compensation. It operates across –40 °C to +125 °C and is commonly used for local on-card regulation in industrial power supplies and embedded control modules.

For engineers reviewing the L78M09ABV datasheet, L78M09ABV pinout, L78M09ABV application, or L78M09ABV equivalent, key selection criteria include dropout voltage (2 V), load regulation (±90 mV over 5–200 mA), supply voltage rejection (56 dB at 120 Hz), quiescent current (6 mA), and extended temperature range support.

Technical Context

The L78M09ABV implements a monolithic series pass transistor architecture with internal current limiting, thermal shutdown, and SOA protection-enabling robust operation without external protection circuitry. Its design eliminates need for external sense leads and supports stable regulation under transient load conditions.

It requires minimal external components: a 0.33 µF input bypass capacitor and 0.1 µF output capacitor are recommended for stability across full load and temperature ranges. The device is not adjustable by default but can be configured as a current regulator or adjustable output using external resistors per Figure 17 and Figure 18 of the datasheet.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	9 V ±2 % (8.82–9.18 V at 25 °C); tight tolerance enables reliable logic-level and analog subsystem biasing
Max Output Current	500 mA continuous; internally limited to prevent damage during overload
Dropout Voltage	2 V at 25 °C; defines minimum VI–VO differential required for regulation
Line Regulation	30 mV (VI = 12–25 V, IO = 200 mA); low sensitivity to input rail variation improves system stability
Load Regulation	90 mV (IO = 5–200 mA); ensures consistent output under dynamic load changes
Supply Voltage Rejection	56 dB at 120 Hz; suppresses ripple from unregulated DC sources like rectified AC
Quiescent Current	6 mA at 25 °C; low standby draw suitable for always-on subsystems
Operating Temperature	–40 °C to +125 °C junction; supports industrial and automotive under-hood environments

Pinout & Package

The L78M09ABV is supplied in the DPAK (TO-252) surface-mount package, offering improved thermal performance over TO-92 while maintaining compact footprint. Thermal resistance is R_thJA = 100 °C/W and R_thJC = 8 °C/W, enabling 500 mA operation with moderate PCB copper area.

Pin/Terminal	Circuit Role	Design Meaning
Input (IN)	Unregulated DC input terminal	Accepts 11.5–24 V DC; must be bypassed with ≥0.33 µF capacitor near pin for high-frequency stability
Ground (GND)	Reference and return path	Common reference for input and output; no separate sense pin-layout grounding critical for accuracy
Output (OUT)	Regulated 9 V output	Delivers up to 500 mA; requires ≥0.1 µF ceramic or tantalum capacitor directly at pin for transient response

Key Features

Feature	Design Value
Thermal Overload Protection	Automatic shutdown at safe junction temperature; recovers autonomously after cooldown
Short-Circuit Current Limit	250 mA typical (700 mA peak); prevents catastrophic failure during sustained fault
SOA Compensation	Reduces short-circuit current as pass transistor V_CE increases-prevents second breakdown
Extended Temp Range	–40 °C to +125 °C operation; qualified for industrial control and motor drive auxiliary rails
Low Output Noise	52 µV RMS (10 Hz–100 kHz); suitable for noise-sensitive analog front-ends and sensor interfaces

Applications

Industrial PLC I/O Module

Automotive Body Control Unit

Use Scenario: Powering isolated digital I/O drivers and ADC reference circuits in modular PLC backplanes.

IC Role / Device Role / Timing Role: Local 9 V regulator supplying isolated 5 V LDOs and optocoupler bias rails.

Use Value: ±2 % tolerance and –40 °C to +125 °C operation ensure signal integrity and long-term calibration stability across ambient extremes.

Use Scenario: Providing stable 9 V supply to microcontroller peripherals and CAN transceiver bias in BCM modules.

IC Role / Device Role / Timing Role: Primary 9 V rail generator feeding downstream 3.3 V/5 V regulators and communication ICs.

Use Value: Built-in short-circuit and thermal protection eliminate need for external fuses or resettable PTCs in space-constrained modules.

Medical Patient Monitor Front-End

Smart Energy Meter MCU Subsystem

Use Scenario: Biasing analog signal conditioning stages (ECG amplifiers, temperature sensors) requiring low-noise, stable DC.

IC Role / Device Role / Timing Role: Low-noise 9 V source for precision op-amp rails and reference buffers.

Use Value: 52 µV RMS output noise and 56 dB SVR minimize interference in sub-mV biomedical signal paths.

Use Scenario: Supplying real-time clock, metrology ASIC, and RF module in battery-backed smart meters.

IC Role / Device Role / Timing Role: Always-on 9 V regulator supporting low-quiescent-current downstream converters.

Use Value: 6 mA quiescent current and robust thermal protection extend battery life and ensure field reliability during brownouts.

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
LM2940CT-9.0/NOPB	Higher dropout (0.6 V typical at 100 mA), lower max current (1 A), wider input range (up to 26 V)	Better suited for low-VI–VO margin designs; less thermally robust at 500 mA in DPAK	Select if input voltage is tightly constrained near 9.6 V and board space allows TO-220
MC78M09BDTRKG	Same 9 V output, ±4 % tolerance, –40 °C to +125 °C, but higher quiescent current (8 mA) and lower SVR (48 dB)	Lower precision and noise performance; acceptable only where cost dominates spec compliance	Choose only for legacy compatibility or non-critical auxiliary rails with relaxed noise/tolerance requirements

Compared with LM2940CT-9.0/NOPB, L78M09ABV offers tighter voltage tolerance and superior thermal protection at 500 mA; versus MC78M09BDTRKG, it delivers 33 % lower quiescent current and 8 dB better ripple rejection-critical for precision analog and low-power systems.

Availability

L78M09ABV is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control units, medical front-end electronics, and smart energy metering systems requiring stable component supply across extended temperature and long product lifecycles.

Supply support for L78M09ABV 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 L78MxxA series was developed to provide rugged, drop-in fixed-voltage regulation for industrial control, instrumentation, and automotive subsystems-emphasizing reliability, thermal resilience, and minimal external component count.

FAQ

What is the minimum input voltage required for L78M09ABV to maintain regulation?

The L78M09ABV requires a minimum input-to-output differential of 2 V at 25 °C to sustain regulation, meaning VI must be ≥11 V for stable 9 V output. At elevated temperatures or full load, this margin may increase slightly due to thermal effects on dropout voltage-designers should allow ≥11.5 V nominal input for robust operation across –40 °C to +125 °C.

Can L78M09ABV be used in parallel to increase output current?

No-L78M09ABV is not designed for parallel operation. Its output voltage tolerance (±2 %) and lack of current-sharing features mean mismatched units will cause one device to dominate conduction, leading to thermal imbalance and premature failure. For >500 mA, use a single higher-current regulator or switch-mode solution instead.

Is an input capacitor mandatory for L78M09ABV stability?

Yes-an input bypass capacitor of ≥0.33 µF (tantalum, ceramic, or mylar) is strongly recommended and effectively mandatory when the regulator is connected via long traces or cables to the power source. This capacitor suppresses high-frequency noise and prevents oscillation caused by source impedance interacting with internal feedback loops.

Does L78M09ABV support adjustable output voltage configurations?

Yes-though optimized as a fixed 9 V regulator, L78M09ABV can be adapted for adjustable output using external resistors per Figure 18 in the datasheet. In that configuration, VO = 7.0 V to 20 V is achievable, provided VI – VO ≥ 2.0 V and external components are selected to preserve thermal and stability margins.

L78M09ABV Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3

Packaging:: Tube

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 1

Voltage - Input (Max):: 35V

Voltage - Output (Min/Fixed):: 9V

Voltage - Output (Max):: -

Voltage Dropout (Max):: -

Current - Output:: 500mA

Current - Quiescent (Iq):: 6 mA

Current - Supply (Max):: -

PSRR:: 56dB (120Hz)

Control Features:: -

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

Operating Temperature:: -40°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

L78M09ABV FAQ

1.How can I place an order for L78M09ABV through Aetrix?

Please submit a Request for Quotation (RFQ) for L78M09ABV 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 L78M09ABV reliable?

The price and inventory of L78M09ABV are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78M09ABV is usually 5 days.

3.What payment methods are accepted for L78M09ABV?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78M09ABV transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L78M09ABV?

L78M09ABV orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L78M09ABV 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 L78M09ABV?

For technical support, including L78M09ABV datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78M09ABV requirements.

6.How does Aetrix verify that L78M09ABV is sourced from the original manufacturer or authorized distributors?

All L78M09ABV 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 L78M09ABV meets industry standards.

7.What is the process for return or replacement of L78M09ABV?

All L78M09ABV units undergo pre-shipment inspection (PSI). If there is an issue with L78M09ABV, 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 L78M09ABV part is unused and in its original packaging.

Return procedure for L78M09ABV:

1.Submit a request within 90 days.

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

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