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Texas Instruments LMR51440SDRRR
- Part No.:
- LMR51440SDRRR
- Manufacturer:
- Texas Instruments
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LMR51440SDRRR.pdf
- Description:
- IC REG BUCK ADJ 4A 12WSON
- Quantity:
- Payment:
- Shipping:
Inventory:14,217
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Product details
Overview
LMR51440SDRRR from Texas Instruments is a 4-A, 4-V to 36-V synchronous step-down DC/DC converter with 25 µA quiescent current, ±1.0% reference voltage accuracy at 25°C, and 75 ns minimum on-time-designed for rugged industrial power conditioning in PLCs, test instrumentation, and major appliances.
For engineers reviewing the LMR51440SDRRR datasheet, LMR51440SDRRR pinout, LMR51440SDRRR application, or LMR51440SDRRR equivalent, key selection criteria include PFM-mode light-load efficiency, spread-spectrum EMI reduction, precision enable UVLO configuration, and WSON-12 thermal performance with RθJA = 47.4°C/W.
Technical Context
The LMR51440SDRRR employs fixed-frequency peak-current mode control with internal compensation and supports both continuous conduction mode (CCM) and pulse-frequency modulation (PFM) at light loads. Its architecture integrates high-side (78 mΩ) and low-side (45 mΩ) MOSFETs, enabling efficient 4-A output with programmable 200 kHz–1.1 MHz switching via RT pin resistor.
It features a precision 0.8-V feedback reference, open-drain PGOOD with 2% hysteresis, cycle-by-cycle current limiting (5.5–7.5 A high-side limit), and thermal shutdown at 160°C with 20°C hysteresis-optimized for stable operation across –40°C to 150°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 36 V - supports wide industrial input sources including 12-V, 24-V, and 36-V rails without external pre-regulation. |
| Output Current | 4 A continuous - delivers full rated load with thermal derating managed via WSON-12 package and DAP thermal pad. |
| Quiescent Current | 25 µA (non-switching) - enables ultra-low standby power in battery-backed or always-on systems. |
| Reference Accuracy | ±1.0% at 25°C - ensures tight output regulation (e.g., ±50 mV on 5-V output) without external trimming. |
| Min. On-Time | 75 ns typical - supports high VIN-to-VOUT ratios (e.g., 24 V → 3.3 V at 500 kHz) without frequency foldback. |
| Switching Frequency | 200 kHz to 1.1 MHz - adjustable via RT-to-GND resistor; default 500 kHz with RT open. |
| Protection Features | Hiccup-mode short-circuit, thermal shutdown (160°C), VIN UVLO (3.9 V rise / 3.4 V fall), and PGOOD monitoring - reduces need for external fault management circuitry. |
Pinout & Package
The LMR51440SDRRR is housed in a thermally enhanced 3.0 mm × 3.0 mm WSON-12 package (DRR) with exposed thermal pad (PGND/DAP) for low-junction-temperature operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1,2,3) | Power switch node | Internally connects high-side drain and low-side source; requires direct connection to power inductor with minimal loop area. |
| BOOT (4) | Bootstrap supply | Drives high-side gate; requires 100-nF ceramic capacitor between BOOT and SW for reliable FET turn-on. |
| PG (5) | Open-drain PGOOD | Asserts low when FB voltage deviates >2% from 0.8 V; needs 10–100 kΩ pullup to logic rail ≤20 V. |
| RT (6) | Frequency set | Analog input for resistor-based fSW programming; open = 500 kHz, short-to-GND = 1 MHz. |
| FB (7) | Voltage feedback | Senses output via resistor divider; 0.8-V internal reference sets VOUT = 0.8 × (1 + RFBB/RFBT). |
| AGND (8) | Analog ground | Reference for internal circuits; must be tied to PGND via small net-tie to avoid noise coupling. |
| EN (9) | Precision enable | Logic-controlled startup: <0.8 V = off, >1.4 V = on; supports external UVLO using resistor divider. |
| VIN (10,11,12) | Input power | Three parallel power inputs reduce IR drop and improve high-current path integrity; connect CIN close to pins. |
| PGND/DAP (13) | Power ground & thermal pad | Internal connection to low-side FET source and exposed DAP; must be soldered to large PCB copper pour for thermal dissipation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous rectification | Eliminates external Schottky diode, reducing BOM count and improving efficiency by up to 5% at mid-load. |
| Internal compensation | Enables stable operation with standard ceramic output capacitors (e.g., 22 µF × 2) without external Type-II/III networks. |
| Spread-spectrum frequency modulation | Reduces peak EMI by ±10% around nominal fSW, easing compliance with CISPR-22 Class B conducted emissions limits. |
| Low dropout mode operation | Maintains regulation down to VIN − VOUT ≈ 0.5 V (e.g., 3.8 V → 3.3 V) via duty-cycle extension and frequency foldback. |
| Functional safety documentation support | Includes FIT rate, failure mode analysis, and diagnostic coverage data-enabling IEC 61508 SIL-2 system-level certification. |
Applications
| PLC Power Supply | Test Instrumentation |
|---|---|
Use Scenario: Providing isolated 5-V/3.3-V rails for microcontroller, ADC, and I/O modules in modular PLC backplanes operating from 24-V field bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering clean, regulated DC power with hiccup-mode fault containment during sensor short circuits. Use Value: 25 µA IQ extends backup battery life; ±1.0% VREF ensures accurate analog measurement reference stability over temperature. | Use Scenario: Generating low-noise 3.3-V supply for high-resolution oscilloscope front-end amplifiers and digitizers powered from universal AC/DC adapter. IC Role / Device Role / Timing Role: Main DC/DC stage converting 12-V intermediate rail to precision analog supply with spread-spectrum EMI suppression. Use Value: 75 ns tON-MIN enables 12 V → 3.3 V conversion at 500 kHz without frequency foldback, minimizing output ripple. |
| Major Appliances | Industrial Power Delivery |
Use Scenario: Powering smart display controllers and Wi-Fi modules in refrigerators and washing machines supplied from 12-V or 24-V battery or SMPS. IC Role / Device Role / Timing Role: System PMIC core regulator supporting deep-sleep modes and fast wake-up via precision EN pin UVLO. Use Value: PFM mode achieves >85% efficiency at 1-mA load, reducing standby power consumption below 35 µW. | Use Scenario: Delivering 4-A 5-V rail to FPGA I/O banks and transceivers in industrial Ethernet switches operating in 40°C–85°C ambient. IC Role / Device Role / Timing Role: High-current point-of-load converter with thermal shutdown and robust 36-V input tolerance for unregulated factory power. Use Value: WSON-12 DAP package achieves 23°C/W effective θJA on 2-layer board, sustaining full 4-A load at 70°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMR51450SDRRR | 5-A rated output, identical pinout and feature set; higher current limit (6.5 A typ) and RDS(on) (78/45 mΩ same). | Used where future-proofing for 5-A peak loads or margin is required; shares same PCB layout and BOM except output inductor/capacitor rating. | Select LMR51450SDRRR only if design requires >4-A continuous output or higher short-circuit headroom. |
| TPS544B25RNVR | 4-A, 3.5–18-V input, 1.5-MHz max fSW, no spread spectrum; uses QFN-16, different pinout, requires external compensation. | Targeted at space-constrained, high-frequency designs where EMI filtering is handled externally; lacks PFM mode and integrated thermal pad. | Choose TPS544B25RNVR only for 12-V-only systems needing >1-MHz switching and willing to add compensation components. |
Compared with LMR51450SDRRR, the LMR51440SDRRR offers tighter current-limit matching to 4-A systems and lower cost; versus TPS544B25RNVR, it provides superior light-load efficiency, integrated thermal management, and simpler layout-making it optimal for industrial 4–36-V applications demanding reliability and ease of use.
Availability
LMR51440SDRRR is available at Aetrix Electronics and suitable for PLC power supplies, test instrumentation, and major appliance control modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LMR51440SDRRR 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management ICs, with decades of expertise in high-reliability industrial power solutions.
The LMR514x0 product line was designed specifically for ruggedized industrial DC/DC conversion-emphasizing wide input range, low IQ, functional safety readiness, and simplified layout in compact WSON packages.
FAQ
What is the maximum input voltage rating for the LMR51440SDRRR?
The LMR51440SDRRR has an absolute maximum input voltage rating of 38 V, but its recommended operating input voltage range is 4 V to 36 V. Operation above 36 V may trigger internal protection or cause reliability degradation; sustained use beyond 36 V is not advised per TI's SLUSEP7 datasheet specifications.
Does the LMR51440SDRRR support adjustable output voltage, and how is it configured?
Yes, the LMR51440SDRRR supports adjustable output voltage from 0.8 V to 28 V using an external resistor divider on the FB pin. The internal 0.8-V reference sets VOUT = 0.8 × (1 + RFBB/RFBT); TI recommends 1% tolerance resistors with RFBT between 10 kΩ and 1 MΩ for optimal noise immunity and light-load efficiency.
How does the LMR51440SDRRR implement spread-spectrum frequency modulation?
The LMR51440SDRRR implements spread-spectrum modulation by dithering its internal oscillator frequency ±10% around the programmed fSW value. This feature is enabled by default in the SDRRR variant and reduces peak conducted EMI amplitude without requiring external filters or layout changes-verified in TI's SLUSEP7 characterization data.
What thermal performance can be expected from the LMR51440SDRRR in a standard 2-layer PCB layout?
In a standard 2-layer evaluation board layout, the LMR51440SDRRR achieves an effective junction-to-ambient thermal resistance (RθJA) of 23°C/W. With 4-A load and 24-V input, this allows sustained operation at ~70°C ambient before reaching the 150°C max junction temperature-assuming proper soldering of the PGND/DAP thermal pad to ≥250 mm² copper pour.
Is the LMR51440SDRRR pin-compatible with other members of the LMR514x0 family?
Yes, the LMR51440SDRRR is pin-compatible with LMR51450SDRRR (5-A version) and LMR51450FNDRRR (FPWM variant), sharing identical WSON-12 (DRR) package, pinout, and footprint. This enables hardware reuse across 4-A and 5-A designs, with only minor BOM updates to output inductors and capacitors required for current scaling.
LMR51440SDRRR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 12-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 28V
- Current - Output:
- 4A
- Frequency - Switching:
- 200kHz ~ 1.1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 12-WSON (3x3)
LMR51440SDRRR FAQ
1.How can I place an order for LMR51440SDRRR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMR51440SDRRR 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 LMR51440SDRRR reliable?
The price and inventory of LMR51440SDRRR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMR51440SDRRR is usually 5 days.
3.What payment methods are accepted for LMR51440SDRRR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMR51440SDRRR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMR51440SDRRR?
LMR51440SDRRR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMR51440SDRRR 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 LMR51440SDRRR?
For technical support, including LMR51440SDRRR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMR51440SDRRR requirements.
6.How does Aetrix verify that LMR51440SDRRR is sourced from the original manufacturer or authorized distributors?
All LMR51440SDRRR 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 LMR51440SDRRR meets industry standards.
7.What is the process for return or replacement of LMR51440SDRRR?
All LMR51440SDRRR units undergo pre-shipment inspection (PSI). If there is an issue with LMR51440SDRRR, 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 LMR51440SDRRR part is unused and in its original packaging.
Return procedure for LMR51440SDRRR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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