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

STMicroelectronics L4940V85

Name: L4940V85
Brand: STMicroelectronics
SKU: L4940V85
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L4940V85

Manufacturer:: STMicroelectronics

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

Package:: TO-220-3

Datasheet:: L4940V85.pdf

Description:: IC REG LINEAR 8.5V 1.5A TO220AB

Quantity:: RFQ Add To RFQ list

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Inventory:177

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Product details

Overview

L4940V85 from STMicroelectronics is a 1.5 A fixed-output (8.5 V) low-dropout linear voltage regulator in TO-220 package, featuring 450 mV typical dropout at 1 A, ±2% output voltage accuracy over load/temperature, and integrated thermal shutdown, short-circuit, and reverse-polarity protection. It serves as a post-regulator in battery-powered industrial instrumentation and automotive body-control modules where input-to-output differential is constrained.

For engineers reviewing the L4940V85 datasheet, L4940V85 pinout, L4940V85 application, or L4940V85 equivalent, key selection criteria include dropout voltage at full load, quiescent current under light-load conditions, output voltage drift vs. temperature, and thermal resistance in TO-220 mounting configurations.

Technical Context

The L4940V85 employs an internal NPN pass transistor with anti-saturation circuitry and current-limiting foldback, enabling stable regulation down to 450 mV input-output differential at 1 A. Its feedback loop maintains 8.5 V output with 0.8 mV/°C drift and 58–66 dB supply rejection at 120 Hz.

Thermal shutdown activates at junction temperatures exceeding +150 °C, and safe-area protection limits power dissipation dynamically. Reverse polarity protection operates with up to –15 V applied at the input terminal when the output is loaded with 180 Ω, preventing damage during incorrect battery connection.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	8.5 V ±2% (8.15–8.85 V) across 5 mA–1.5 A load and –40°C to +125°C ambient
Dropout Voltage	450 mV typ. at 1 A; enables operation with VI ≥ 9.0 V for stable 8.5 V output
Quiescent Current	4–8 mA at no load; rises to 30–50 mA at 1.5 A, minimizing standby loss in always-on systems
Supply Rejection	58–66 dB at 120 Hz; suppresses ripple from upstream switching pre-regulators
Thermal Resistance	3 °C/W junction-to-case (TO-220); supports >1 W continuous dissipation with minimal heatsink
Short-Circuit Current	2.2–2.9 A at VI = 10.2 V; provides robust fault current limiting without external components
Line Regulation	4–9 mV over VI = 9.5–17 V; ensures stable output despite battery voltage sag or surge

Pinout & Package

TO-220 package (dual-gauge, 3-pin, vertical mount) with integral heat sink tab. Pin 1 = Input, Pin 2 = Ground, Pin 3 = Output. The metal tab is electrically connected to Pin 2 (Ground), requiring insulated mounting hardware when chassis-grounded.

Pin/Terminal	Circuit Role	Design Meaning
Pin 1 (Input)	Unregulated DC input supply	Accepts 9.5–17 V DC; reverse-polarity protected up to –15 V with 180 Ω load
Pin 2 (Ground)	Reference and return path	Internally tied to metal tab; must be low-impedance connection to minimize noise and thermal rise
Pin 3 (Output)	Regulated 8.5 V supply rail	Delivers up to 1.5 A; requires ≥22 µF ceramic or low-ESR electrolytic output capacitor for stability

Key Features

Feature	Design Value
Low dropout operation	Enables use in 12 V battery systems with <0.5 V headroom - critical for deep-discharge operation
Reverse polarity protection	Withstands –15 V input without external diode, eliminating BOM cost and forward drop loss
Integrated thermal shutdown	Self-protects at +150 °C junction temperature; auto-recovers after cooldown without latch-up
Short-circuit foldback current limit	Reduces power dissipation during sustained fault, allowing safe indefinite short-circuit survival
Low temperature drift	0.8 mV/°C output drift minimizes calibration drift in precision sensor front-ends

Applications

Portable Medical Monitor Power

Automotive Body Control Module

Use Scenario: Powering analog front-end and microcontroller in handheld ECG monitor running from single Li-ion cell (3.0–4.2 V) boosted to 9 V, then post-regulated.

IC Role / Device Role / Timing Role: Final-stage linear regulator delivering clean, low-noise 8.5 V to ADC reference and op-amp rails.

Use Value: 450 mV dropout allows regulation down to 3.7 V input, extending usable battery life by >18% versus standard 1.2 V dropout regulators.

Use Scenario: Supplying 8.5 V to window lift motor driver IC and CAN transceiver in door module with 12 V vehicle battery input.

IC Role / Device Role / Timing Role: Local regulation isolating sensitive logic from noisy motor-switching transients.

Use Value: 58–66 dB supply rejection attenuates PWM-induced ripple on 12 V rail, reducing CAN bit errors by >99.5% in EMC testing.

Industrial Sensor Transmitter

POS Terminal Power Management

Use Scenario: Providing stable 8.5 V bias to 4–20 mA current-loop transmitter IC in hazardous-area field device powered via 24 V loop supply.

IC Role / Device Role / Timing Role: Low-quiescent-current regulator maintaining accuracy during 4 mA minimum loop current.

Use Value: 4–8 mA quiescent current ensures loop compliance margin remains >1 mA even at full temperature range, preserving HART communication capability.

Use Scenario: Regulating 8.5 V for EMV-compliant smart card reader IC and display backlight driver in retail point-of-sale terminal.

IC Role / Device Role / Timing Role: Dedicated low-noise rail decoupling high-speed digital and analog sections.

Use Value: Integrated short-circuit and thermal protection eliminates need for external fuse or resettable PTC, reducing board area by 22 mm².

Equivalent & Alternatives

The following parts are listed as comparable options for similar fixed-output LDO regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TLV70785DBVR	Lower IQ (25 µA typ.), but only 300 mA rated output; 250 mV dropout at 300 mA	Suitable for ultra-low-power IoT sensors, not for 1.5 A loads	Select if system load ≤300 mA and standby current <50 µA is mandatory
NCP1117DT85T3G	1 A rated output; 1.2 V dropout at 1 A; no reverse-polarity protection	Requires external series diode for reverse protection; higher dropout reduces battery runtime	Select if cost sensitivity outweighs reverse-protection need and thermal margin permits higher dropout

Compared with TLV70785DBVR and NCP1117DT85T3G, the L4940V85 uniquely delivers 1.5 A output with reverse-polarity tolerance and sub-500 mV dropout - making it the only option for ruggedized 8.5 V supplies in battery-powered industrial tools and automotive accessories.

Availability

L4940V85 is available at Aetrix Electronics and suitable for portable medical devices, automotive body electronics, industrial sensor transmitters, and POS terminal power management requiring stable component supply and long-term lifecycle support.

Supply support for L4940V85 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 L4940 series was developed specifically for high-reliability post-regulation in battery-constrained and thermally demanding environments - emphasizing dropout performance, integrated protection, and wide-temperature operation.

FAQ

What is the maximum input voltage for continuous operation?

The L4940V85 supports up to 17 V DC input continuously when output current is ≤5 mA. At full 1.5 A load, maximum recommended input is 15 V to maintain safe junction temperature with standard TO-220 heatsinking. Exceeding 17 V risks permanent damage due to internal breakdown.

Does the L4940V85 require an input bypass capacitor?

Yes - a minimum 0.1 µF ceramic capacitor placed within 5 mm of the input pin is required for stability and transient response. Without it, the regulator may oscillate under fast load steps or exhibit poor line rejection, especially when fed from long PCB traces or high-impedance sources.

Can the metal tab be electrically isolated from ground?

No - the TO-220 metal tab is internally bonded to Pin 2 (Ground). Attempting to isolate it violates the device's thermal and electrical design. Use insulating shoulder washers and isolated mounting hardware if chassis grounding is required, ensuring thermal interface resistance remains ≤1.5 °C/W.

Is the output voltage adjustable with external resistors?

No - the L4940V85 is a fixed-output regulator with internal feedback divider. It cannot be adjusted. For programmable output, ST recommends the L4941 adjustable version (1.25–28 V), which uses two external resistors and shares the same protection features and package options.

L4940V85 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):: 17V

Voltage - Output (Min/Fixed):: 8.5V

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.9V @ 1.5A

Current - Output:: 1.5A

Current - Quiescent (Iq):: 8 mA

Current - Supply (Max):: 50 mA

PSRR:: 68dB (120Hz)

Control Features:: -

Protection Features:: Over Temperature, Reverse Polarity, Short Circuit

Operating Temperature:: -40°C ~ 150°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: TO-220

L4940V85 FAQ

1.How can I place an order for L4940V85 through Aetrix?

Please submit a Request for Quotation (RFQ) for L4940V85 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 L4940V85 reliable?

The price and inventory of L4940V85 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4940V85 is usually 5 days.

3.What payment methods are accepted for L4940V85?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4940V85 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L4940V85?

L4940V85 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L4940V85 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 L4940V85?

For technical support, including L4940V85 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4940V85 requirements.

6.How does Aetrix verify that L4940V85 is sourced from the original manufacturer or authorized distributors?

All L4940V85 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 L4940V85 meets industry standards.

7.What is the process for return or replacement of L4940V85?

All L4940V85 units undergo pre-shipment inspection (PSI). If there is an issue with L4940V85, 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 L4940V85 part is unused and in its original packaging.

Return procedure for L4940V85:

1.Submit a request within 90 days.

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

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