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

STMicroelectronics L7809CF

Name: L7809CF
Brand: STMicroelectronics
SKU: L7809CF
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L7809CF

Manufacturer:: STMicroelectronics

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

Package:: TO-220-3

Datasheet:: L7809CF.pdf

Description:: IC REG LINEAR 9V 1.5A TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:2,005

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Product details

Overview

L7809CF from STMicroelectronics is a three-terminal positive linear voltage regulator delivering a fixed 9 V output with up to 1.5 A continuous current, thermal overload and short-circuit protection, and ±2 % output voltage tolerance (A-grade), used in industrial power supplies and embedded control boards requiring stable local regulation.

For engineers reviewing the L7809CF datasheet, L7809CF pinout, L7809CF application, or L7809CF equivalent, this page provides verified electrical characteristics, TO-220FP package details, thermal resistance data, load/line regulation limits, and real-world use cases for board-level DC-DC conversion where input voltage ranges from 11.5 V to 26 V.

Technical Context

This device operates as a monolithic series pass regulator with internal current limiting, safe operating area (SOA) protection, and thermal shutdown circuitry. It requires no external components for basic operation but supports adjustable output via external resistors when configured as a floating regulator.

Designed for fixed-output applications, it maintains regulation across junction temperatures from −40 °C to 125 °C (AB grade), with dropout voltage of 2 V at 1 A and supply voltage rejection of 55 dB at 120 Hz under specified test conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	9 V ±2 % (guaranteed over temperature and load; enables precise logic supply for 9 V–tolerant microcontrollers)
Max Output Current	1.5 A (continuous; sufficient for powering multiple analog sensors and low-power peripherals)
Input Voltage Range	11.5 V to 26 V (supports 12 V nominal systems with ripple and transients)
Dropout Voltage	2 V at 1 A (requires ≥11 V input for stable 9 V output under full load)
Line Regulation	≤180 mV (over VI = 11.5–26 V; ensures <2 % output shift during input variation)
Load Regulation	≤180 mV (over IO = 5 mA–1.5 A; maintains tight output stability across dynamic loads)
Quiescent Current	8 mA (low standby draw; suitable for always-on monitoring circuits)
Thermal Resistance (Junction-to-Case)	5 °C/W (TO-220FP package; enables >1 A operation with modest heatsinking)

Pinout & Package

The L7809CF is housed in a TO-220FP (Full Pack) thermally enhanced plastic package with three terminals: Input, Ground, and Output. The metal tab is electrically connected to the ground terminal and serves as the primary heat path.

Pin/Terminal	Circuit Role	Design Meaning
1 (Input)	Unregulated DC input	Accepts 11.5–26 V; must be decoupled with ≥0.33 µF ceramic capacitor close to pin
2 (Ground)	Common reference and thermal path	Connected to PCB ground plane and heatsink; electrically tied to metal tab
3 (Output)	Regulated 9 V output	Delivers stable 9 V to load; requires ≥0.1 µF ceramic capacitor at pin for stability

Key Features

Feature	Design Value
Thermal overload protection	Automatic shutdown at T_J ≥ 165 °C; resumes after cooldown - prevents permanent damage during sustained overload
Short-circuit current limit	0.4 A typical short-circuit current (I_SC); limits fault energy and enables safe recovery without external fusing
Output transition SOA protection	Internal safe operating area circuitry prevents transistor destruction during transient overloads or capacitive load switching
Extended temperature range	−40 °C to +125 °C operating junction range (AB grade); qualified for industrial and automotive under-hood environments
Low output noise	70 µV/V RMS (10 Hz–100 kHz); minimizes interference in analog signal chains and precision ADC references

Applications

Industrial PLC I/O Module

Automotive Body Control Unit

Use Scenario: Powering isolated digital I/O drivers and analog sensor interfaces on a DIN-rail mounted programmable logic controller.

IC Role / Device Role / Timing Role: Local 9 V regulator supplying V_CC to optocouplers, RS-485 transceivers, and 8-bit microcontrollers.

Use Value: Eliminates single-point regulation losses and improves noise immunity by placing regulation directly at point-of-load.

Use Scenario: Providing stable 9 V rail for interior lighting controllers and door module microcontrollers in 12 V vehicle architectures.

IC Role / Device Role / Timing Role: Primary post-buck regulation stage converting noisy battery-derived 12 V to clean 9 V for MCU core and CAN transceiver logic.

Use Value: Withstands cold-crank (down to 6 V) and load-dump (up to 35 V) transients due to integrated protection and wide input range.

Medical Patient Monitor Front-End

Test & Measurement Equipment Power Stage

Use Scenario: Supplying bias voltage to low-noise instrumentation amplifiers and analog front-end filters in portable ECG units.

IC Role / Device Role / Timing Role: Low-noise 9 V source for analog signal conditioning stages requiring high PSRR and minimal ripple.

Use Value: 70 µV/V output noise and 55 dB supply rejection ensure signal integrity in sub-mV biomedical measurements.

Use Scenario: Generating calibrated 9 V reference rails for multimeter analog sections and calibration circuitry.

IC Role / Device Role / Timing Role: Precision local regulator ensuring stable excitation voltage for reference dividers and DAC buffers.

Use Value: ±2 % output tolerance and <180 mV load regulation support metrology-grade accuracy without trimming.

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
LM7809CT	Same 9 V output, TO-220 package, but higher quiescent current (8 mA vs. 6 mA for A-grade variants); no AB-grade extended temp option	Rated only for 0–125 °C operation; unsuitable for automotive or outdoor industrial deployments	Select when cost sensitivity outweighs temperature range and noise requirements
MC7809BD2TR4G	D²PAK package, lower R_thJC (3 °C/W), but wider output tolerance (±4 %); no AB-grade variant available	Better thermal performance in high-density layouts, but reduced voltage accuracy limits use in precision analog rails	Select when board space and thermal dissipation are critical, and ±4 % output is acceptable

Compared with LM7809CT and MC7809BD2TR4G, the L7809CF offers guaranteed −40 °C to +125 °C operation, tighter 9 V tolerance, and lower output noise-making it optimal for mission-critical industrial and automotive applications where reliability and signal integrity are prioritized over lowest BOM cost.

Availability

L7809CF is available at Aetrix Electronics and suitable for industrial PLCs, automotive body control modules, medical patient monitors, and test equipment requiring stable component supply with long-term lifecycle assurance.

Supply support for L7809CF 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer markets.

The L78 series belongs to ST's legacy positive voltage regulator product line, engineered for robustness and simplicity in local DC-DC conversion across harsh environments and cost-sensitive designs.

FAQ

What is the minimum required input voltage for stable 9 V output at 1.5 A?

The L7809CF requires a minimum input voltage of 11 V to maintain regulation at full 1.5 A load, based on its 2 V dropout specification. For reliable operation across temperature and process variation, ST recommends maintaining ≥11.5 V input per Table 14 in DS0422 Rev 38.

Can L7809CF be used without input/output capacitors?

No. ST specifies mandatory 0.33 µF ceramic input capacitor (placed ≤1 cm from pin 1) and 0.1 µF ceramic output capacitor (placed ≤1 cm from pin 3) to ensure stability and transient response. Omission risks oscillation, overshoot, or thermal shutdown under load changes.

Is the metal tab on the TO-220FP package electrically isolated?

No. The metal tab is internally connected to pin 2 (Ground) and must be electrically tied to system ground. When mounted to a heatsink, use an insulating washer and shoulder washer only if galvanic isolation from chassis ground is required - otherwise, direct mounting maximizes thermal performance.

How does L7809CF handle reverse voltage on the output pin?

The L7809CF lacks reverse-voltage protection. If output voltage exceeds input (e.g., during power-down sequencing), current flows backward through the internal pass transistor, potentially damaging the IC. A series Schottky diode from output to input is recommended in systems with multiple power domains or backup supplies.

L7809CF 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):: 2V @ 1A (Typ)

Current - Output:: 1.5A

Current - Quiescent (Iq):: 8 mA

Current - Supply (Max):: -

PSRR:: 55dB (120Hz)

Control Features:: -

Protection Features:: Over Temperature, Short Circuit

Operating Temperature:: 0°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

L7809CF FAQ

1.How can I place an order for L7809CF through Aetrix?

Please submit a Request for Quotation (RFQ) for L7809CF 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 L7809CF reliable?

The price and inventory of L7809CF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L7809CF is usually 5 days.

3.What payment methods are accepted for L7809CF?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L7809CF transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L7809CF?

L7809CF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L7809CF 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 L7809CF?

For technical support, including L7809CF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L7809CF requirements.

6.How does Aetrix verify that L7809CF is sourced from the original manufacturer or authorized distributors?

All L7809CF 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 L7809CF meets industry standards.

7.What is the process for return or replacement of L7809CF?

All L7809CF units undergo pre-shipment inspection (PSI). If there is an issue with L7809CF, 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 L7809CF part is unused and in its original packaging.

Return procedure for L7809CF:

1.Submit a request within 90 days.

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

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