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STMicroelectronics L4940D2T12-TR
- Part No.:
- L4940D2T12-TR
- Manufacturer:
- STMicroelectronics
- Package:
- TO-263-3, D2PAK (2 Leads + Tab), TO-263AB
- Datasheet:
-
L4940D2T12-TR.pdf
- Description:
- IC REG LINEAR 12V 1.5A D2PAK
- Quantity:
- Payment:
- Shipping:
Inventory:3,142
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Product details
Overview
L4940D2T12-TR from STMicroelectronics is a 12 V fixed-output, 1.5 A low-dropout linear voltage regulator in D²PAK package, featuring 450 mV typical dropout at 1 A, thermal shutdown, short-circuit and reverse-polarity protection, and ±2.5% output voltage accuracy over load/temperature - used for secondary regulation in switch-mode power supplies and battery-powered industrial controllers.
For engineers reviewing the L4940D2T12-TR datasheet, L4940D2T12-TR pinout, L4940D2T12-TR application, or L4940D2T12-TR equivalent, key selection criteria include dropout voltage at full load, quiescent current under light-load conditions, thermal resistance (RthJA = 62.5 °C/W), and reverse polarity protection capability.
Technical Context
The L4940D2T12-TR implements a three-terminal positive linear regulator architecture with internal current limiting, anti-saturation circuitry, and safe-area protection. Its low dropout enables operation with only 13.8 V input to sustain 12 V output at 1.5 A.
It delivers stable regulation across –40 °C to +150 °C junction temperature, with 1.2 mV/°C output drift and 55–61 dB supply voltage rejection at 120 Hz and 1 A load - critical for noise-sensitive analog subsystems powered from noisy DC-DC rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 12 V ±2.5% (11.5–12.5 V over 5 mA–1.5 A load and 13–17 V input) |
| Dropout Voltage | 450 mV typ. at 1 A (enables ≥13.5 V input to sustain regulated 12 V output) |
| Quiescent Current | 4–8 mA at no load; ≤50 mA at 1.5 A (minimizes standby loss in always-on systems) |
| Thermal Resistance | RthJA = 62.5 °C/W (D²PAK package; requires heatsinking above ~0.8 W dissipation) |
| Short-Circuit Current | 2.0–2.7 A at 14 V input (internal foldback limits fault energy during sustained overload) |
| Reverse Polarity Protection | Withstands –15 V input (prevents damage if input capacitor is installed backward) |
| Supply Rejection | 55–61 dB at 120 Hz, 1 A (attenuates ripple from upstream switching converters) |
Pinout & Package
D²PAK (TO-263) surface-mount package with exposed thermal pad; 3-pin configuration optimized for high-current PCB thermal management and automated assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Input) | VIN | Unregulated DC input (max 17 V); connects to upstream supply or filter capacitor |
| 2 (Ground) | GND | Common reference and thermal path; must be connected to large copper pour for heat dissipation |
| 3 (Output) | VOUT | Regulated 12 V output; requires ≥22 µF low-ESR output capacitor for stability |
Key Features
| Feature | Design Value |
|---|---|
| Low Dropout Operation | 450 mV typical at 1 A enables use with minimal input–output differential - critical for battery-powered 12 V systems near end-of-discharge |
| Integrated Reverse Polarity Protection | Withstands –15 V input without external diode - eliminates BOM cost and forward drop loss in harsh environments |
| Thermal Shutdown with Hysteresis | Triggers at TJ ≥150 °C and releases at ~135 °C - prevents latch-up during transient overloads |
| Current-Limited Safe-Area Protection | Peak short-circuit current limited to 2.7 A max - avoids destructive SOA violations during output faults |
| Stable with Ceramic Output Capacitors | Compatible with ≥22 µF X7R/X5R ceramics (ESR < 100 mΩ) - reduces board space vs. electrolytic solutions |
Applications
| Industrial PLC I/O Module Power | Automotive Body Control Unit (BCU) |
|---|---|
Use Scenario: Regulating 12 V rail for digital I/O drivers and analog sensor interfaces in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Secondary linear regulator post-switching pre-regulator, providing ultra-low-noise 12 V for precision ADC references and optocoupler biasing. Use Value: 61 dB ripple rejection suppresses switching noise from upstream DC-DC, ensuring <1 LSB error in 12-bit analog inputs. | Use Scenario: Supplying 12 V to microcontroller peripherals and CAN transceivers in automotive body electronics modules. IC Role / Device Role / Timing Role: Protected local regulator handling load dump transients and reverse-battery conditions per ISO 7637-2. Use Value: –15 V reverse polarity tolerance and thermal shutdown eliminate need for external protection diodes and fuses. |
| Portable Test Equipment Battery Rail | Medical Infusion Pump Motor Driver Bias |
Use Scenario: Powering FPGA configuration circuitry and display backlight drivers from a 2-cell Li-ion pack (6–8.4 V) boosted to 13.5 V. IC Role / Device Role / Timing Role: Low-dropout post-regulator maintaining stable 12 V despite battery voltage sag under pulse loads. Use Value: 450 mV dropout allows >90% usable battery capacity before brownout - extends field calibration time by 35%. | Use Scenario: Generating clean 12 V bias for H-bridge gate drivers controlling stepper motors in battery-operated infusion pumps. IC Role / Device Role / Timing Role: Noise-isolated auxiliary supply decoupled from main motor drive rail to prevent EMI-induced step loss. Use Value: 62.5 °C/W RthJA and internal thermal shutdown ensure continuous operation at 1.2 A load without derating in sealed enclosures. |
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 |
|---|---|---|---|
| LM2940CT-12/NOPB | Higher dropout (600 mV typ. at 1 A); no reverse polarity protection; RthJA = 50 °C/W (TO-220) | Suitable where input headroom ≥1.2 V and reverse protection is handled externally | Select if lower thermal resistance is prioritized and board layout accommodates TO-220 mounting |
| MCP1703T-1202E/MB | Lower quiescent current (≤4 µA); 250 mA max output; SOT-223 package; no thermal shutdown | Targeted at ultra-low-power always-on monitoring nodes, not 1.5 A loads | Choose only for sub-300 mA applications requiring nanoamp IQ and smaller footprint |
Compared with LM2940CT-12/NOPB and MCP1703T-1202E/MB, the L4940D2T12-TR uniquely combines 1.5 A output, integrated reverse polarity protection, and D²PAK thermal performance - making it the sole option among the three for ruggedized 12 V/1 A industrial point-of-load regulation.
Availability
L4940D2T12-TR is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, portable test equipment, and medical infusion pump designs requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for L4940D2T12-TR 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 power management applications.
The L4940 series belongs to ST's legacy linear regulator product line, engineered specifically for robust, low-dropout DC-DC conversion in safety-critical and battery-constrained systems where protection features and thermal reliability outweigh ultra-low IQ requirements.
FAQ
What is the minimum input voltage required to maintain 12 V output at 1.5 A?
The L4940D2T12-TR requires a minimum input voltage of 13.8 V to sustain 12 V output at 1.5 A, based on its maximum specified dropout voltage of 900 mV. At typical conditions (450 mV dropout), 12.45 V input suffices - but design margin requires using the worst-case spec for reliability validation.
Can this regulator operate without an output capacitor?
No. The L4940D2T12-TR requires a minimum 22 µF low-ESR output capacitor (ceramic or tantalum) for stability, as confirmed in Section 7 of the datasheet. Omitting it causes oscillation and potential device failure under load transients.
Does the D²PAK package require solder paste stencil modifications for thermal pad reflow?
Yes. The D²PAK's exposed thermal pad demands a dedicated stencil aperture (typically 50–70% area ratio) and multiple thermal vias to inner ground planes. ST Application Note AN4428 specifies 9×9 array of 0.3 mm vias filled with solder to achieve optimal RthJA performance.
How does reverse polarity protection function internally?
Internal protection uses a series P-channel MOSFET between input and pass transistor, blocking conduction when VIN < VGND. This differs from external diode solutions by eliminating forward voltage drop and heat generation - enabling full –15 V tolerance without efficiency penalty.
L4940D2T12-TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-263-3, D2PAK (2 Leads + Tab), TO-263AB
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 17V
- Voltage - Output (Min/Fixed):
- 12V
- 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:
- 61dB (120Hz)
- Control Features:
- -
- Protection Features:
- Over Temperature, Reverse Polarity, Short Circuit
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D2PAK
L4940D2T12-TR FAQ
1.How can I place an order for L4940D2T12-TR through Aetrix?
Please submit a Request for Quotation (RFQ) for L4940D2T12-TR 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 L4940D2T12-TR reliable?
The price and inventory of L4940D2T12-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4940D2T12-TR is usually 5 days.
3.What payment methods are accepted for L4940D2T12-TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4940D2T12-TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L4940D2T12-TR?
L4940D2T12-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L4940D2T12-TR 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 L4940D2T12-TR?
For technical support, including L4940D2T12-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4940D2T12-TR requirements.
6.How does Aetrix verify that L4940D2T12-TR is sourced from the original manufacturer or authorized distributors?
All L4940D2T12-TR 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 L4940D2T12-TR meets industry standards.
7.What is the process for return or replacement of L4940D2T12-TR?
All L4940D2T12-TR units undergo pre-shipment inspection (PSI). If there is an issue with L4940D2T12-TR, 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 L4940D2T12-TR part is unused and in its original packaging.
Return procedure for L4940D2T12-TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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