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

STMicroelectronics L78M09CP

Name: L78M09CP
Brand: STMicroelectronics
SKU: L78M09CP
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L78M09CP

Manufacturer:: STMicroelectronics

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

Package:: TO-220-3 Full Pack

Datasheet:: L78M09CP.pdf

Description:: IC REG LINEAR 9V 500MA TO220FP

Quantity:: RFQ Add To RFQ list

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Inventory:2,062

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Product details

Overview

L78M09CP 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, and short-circuit current limiting. It operates across an input range of 11.5–24 V and is commonly used for local on-card regulation in industrial control modules, sensor signal conditioning circuits, and embedded microcontroller power supplies.

For engineers reviewing the L78M09CP datasheet, L78M09CP pinout, L78M09CP application, or L78M09CP equivalent, key selection considerations include dropout voltage (2 V), load regulation (±90 mV over 5–200 mA), supply voltage rejection (56 dB at 120 Hz), and extended temperature operation (−40 °C to +125 °C for AB grade).

Technical Context

The L78M09CP implements a monolithic silicon pass transistor with internal current limiting, thermal shutdown, and safe-area compensation-ensuring robustness under overload, short-circuit, and high-temperature conditions. Its architecture eliminates external feedback components, relying on trimmed resistor networks for precise 9 V output calibration.

It requires no external compensation for stability with standard 0.33 µF input and 0.1 µF output capacitors. The device's SOA protection dynamically reduces short-circuit current as pass transistor V_CE increases, preventing second breakdown during fault events.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	9 V ±2 % (8.82–9.18 V at 25 °C; 8.64–9.36 V over full load and input range)
Max Output Current	500 mA continuous (internally limited; peak short-circuit current 700 mA)
Dropout Voltage	2 V typical at 25 °C - defines minimum VI–VO differential needed for regulation
Supply Voltage Rejection	56 dB at 120 Hz - suppresses ripple from unregulated DC sources like rectified AC
Load Regulation	±90 mV over 5–200 mA at 25 °C - ensures stable output despite varying load current
Quiescent Current	6 mA typical - contributes directly to no-load power loss in battery-sensitive designs
Operating Temperature	−40 °C to +125 °C (AB grade) - supports industrial and automotive under-hood environments

Pinout & Package

Available in TO-220 package (3-lead, through-hole) with standard heat sink mounting capability. Thermal resistance junction-to-case is 3 °C/W, enabling >500 mA operation with adequate heatsinking.

Pin/Terminal	Circuit Role	Design Meaning
1 (Input)	Unregulated DC input supply	Accepts 11.5–24 V; must be bypassed with ≥0.33 µF capacitor near pin for stability
2 (Ground)	Common reference and return path	No sense lead - layout must minimize ground impedance to avoid regulation error
3 (Output)	Regulated 9 V DC output	Stable under 5–500 mA loads; requires ≥0.1 µF output capacitor for transient response

Key Features

Feature	Design Value
Fixed 9 V output with ±2 % tolerance	Eliminates external resistor divider; enables drop-in replacement in legacy 9 V rail designs
Thermal overload protection	Shuts down output above safe junction temperature (125 °C), then auto-recovers when cooled
Short-circuit current limiting	Clamps output to ~250 mA (typ.) during sustained short, preventing device destruction
SOA (Safe Operating Area) protection	Reduces short-circuit current as V_CE rises - prevents second breakdown during fault transients
Low output noise	52 µV RMS (10 Hz–100 kHz) - suitable for analog sensor front-ends and low-noise MCU supplies

Applications

Industrial PLC I/O Module

Automotive Body Control Unit

Use Scenario: Powering isolated 9 V analog input channels and digital isolators in modular PLC backplanes.

IC Role / Device Role / Timing Role: Local point-of-load regulator providing clean, stable 9 V for op-amp biasing and ADC reference buffers.

Use Value: ±2 % tolerance and 56 dB ripple rejection ensure <10 mV output variation under noisy 24 V bus conditions.

Use Scenario: Supplying 9 V to LIN transceivers and door module microcontrollers in non-safety-critical vehicle subsystems.

IC Role / Device Role / Timing Role: Primary 9 V regulator for LIN physical layer ICs requiring stable V_CC within −40 °C to +125 °C ambient.

Use Value: Extended temperature rating and thermal shutdown enable reliable operation without derating in confined enclosures.

Medical Patient Monitor Sensor Interface

IoT Edge Node Power Management

Use Scenario: Regulating power for precision biopotential amplifiers and thermistor signal chains in portable monitors.

IC Role / Device Role / Timing Role: Low-noise 9 V source for instrumentation-grade op-amps and 16-bit SAR ADC references.

Use Value: 52 µV RMS output noise avoids degrading SNR in sub-µV-level ECG/EEG signal paths.

Use Scenario: Providing 9 V bias to RF power amplifiers and LoRaWAN transceivers in battery-backed gateways.

IC Role / Device Role / Timing Role: Secondary regulated rail derived from buck converter output, supporting burst-mode transmit peaks.

Use Value: 700 mA peak short-circuit capability handles transient current surges during RF transmission without latch-up.

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
LM7809CDT	±4 % output tolerance; 0–125 °C operating range; higher quiescent current (8 mA)	Lacks extended −40 °C rating and tighter initial accuracy - unsuitable for cold-environment industrial use	Lower-cost option where ambient temperature stays above 0 °C and ±4 % output is acceptable
MC7809BDTRKG	±4 % tolerance; 0–125 °C; lower dropout (1.7 V typ.); TO-252 (DPAK) only	No TO-220 variant; reduced thermal margin at 500 mA due to higher R_thJA (100 °C/W)	Preferred for surface-mount layouts with space constraints, but requires careful thermal design

Compared with LM7809CDT and MC7809BDTRKG, the L78M09CP offers superior initial accuracy (±2 % vs. ±4 %), wider temperature support (−40 °C to +125 °C), and proven TO-220 thermal performance - making it the preferred choice for industrial and automotive applications demanding long-term stability and ruggedness.

Availability

L78M09CP is available at Aetrix Electronics and suitable for industrial control systems, automotive body electronics, medical sensor interfaces, and IoT edge node power supplies requiring stable component supply, long-lifecycle availability, and guaranteed parametric compliance.

Supply support for L78M09CP 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 L78MxxA series belongs to ST's precision linear regulator product line, engineered specifically for robust local regulation in harsh environments where reliability, thermal resilience, and tight output tolerance are critical.

FAQ

What is the minimum input voltage required for the L78M09CP to maintain regulation?

The L78M09CP requires a minimum input-to-output differential of 2 V (dropout voltage) to sustain regulation. With a nominal 9 V output, this means the input must be at least 11 V under typical conditions. At full 500 mA load and elevated temperature, the dropout may increase slightly, so 11.5 V is recommended as the practical minimum per datasheet test conditions.

Can the L78M09CP be used in parallel to increase output current?

No - the L78M09CP is not designed for parallel operation. Its output voltage tolerance (±2 %) and lack of current-sharing circuitry mean mismatched units will cause one device to carry most of the load, leading to thermal imbalance and premature failure. For higher current, use a single higher-rated regulator or a switching solution.

Does the L78M09CP require input and output capacitors, and what values are recommended?

Yes - ST specifies a minimum 0.33 µF ceramic or tantalum capacitor at the input and 0.1 µF at the output for stability and transient response. These values are validated across temperature and load; larger values improve ripple suppression but do not affect basic regulation. Mount capacitors with shortest possible leads directly at the pins.

How does the L78M09CP behave during a sustained output short-circuit?

Under sustained short-circuit, the L78M09CP limits output current to ~250 mA (typ.), activates thermal shutdown if junction temperature exceeds ~160 °C, and enters safe oscillatory mode - cycling between conduction and shutdown until the fault clears. This protects both the IC and PCB traces without requiring external fusing.

L78M09CP Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: TO-220-3 Full Pack

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:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220FP

L78M09CP FAQ

1.How can I place an order for L78M09CP through Aetrix?

Please submit a Request for Quotation (RFQ) for L78M09CP 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 L78M09CP reliable?

The price and inventory of L78M09CP are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L78M09CP is usually 5 days.

3.What payment methods are accepted for L78M09CP?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L78M09CP transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L78M09CP?

L78M09CP orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L78M09CP 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 L78M09CP?

For technical support, including L78M09CP datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L78M09CP requirements.

6.How does Aetrix verify that L78M09CP is sourced from the original manufacturer or authorized distributors?

All L78M09CP 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 L78M09CP meets industry standards.

7.What is the process for return or replacement of L78M09CP?

All L78M09CP units undergo pre-shipment inspection (PSI). If there is an issue with L78M09CP, 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 L78M09CP part is unused and in its original packaging.

Return procedure for L78M09CP:

1.Submit a request within 90 days.

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

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