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Texas Instruments LMR51450FNDRRR
- Part No.:
- LMR51450FNDRRR
- Manufacturer:
- Texas Instruments
- Package:
- 12-WFDFN Exposed Pad
- Datasheet:
-
LMR51450FNDRRR.pdf
- Description:
- IC REG BUCK ADJ 5A 12WSON
- Quantity:
- Payment:
- Shipping:
Inventory:1,768
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Product details
Overview
LMR51450FNDRRR from Texas Instruments is a 36-V, 5-A synchronous step-down DC/DC converter with forced PWM (FPWM) operation, ±1.0% reference voltage accuracy at room temperature, 75 ns minimum on-time, 25 µA quiescent current, and WSON-12 package-designed for industrial power conditioning in PLCs, test instrumentation, and major appliances.
For engineers reviewing the LMR51450FNDRRR datasheet, LMR51450FNDRRR pinout, LMR51450FNDRRR application, or LMR51450FNDRRR equivalent, key selection considerations include FPWM mode for constant-frequency low-ripple operation, thermal shutdown at 160°C, cycle-by-cycle current limiting (6.4–9.6 A high-side), precision enable input with UVLO programmability, and compatibility with 0.8 V feedback reference for adjustable output regulation.
Technical Context
The LMR51450FNDRRR employs fixed-frequency peak-current mode control with internal compensation, enabling stable regulation across wide input (4–36 V) and output (0.8–28 V) ranges without external loop components. Its FPWM variant maintains constant switching frequency (200–1100 kHz) and tight output voltage ripple over full load, unlike PFM variants that sacrifice frequency stability for light-load efficiency.
It integrates high-side (78 mΩ) and low-side (45 mΩ) MOSFETs, supports adjustable frequency via RT pin resistor, and features open-drain PGOOD with 110–115% rising threshold and 88–92% falling threshold relative to FB voltage-enabling reliable system reset signaling during output faults or startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 36 V - supports unregulated industrial rails including 12 V, 24 V, and 36 V battery or bus supplies. |
| Output Current | 5 A continuous - delivers full rated load without derating under typical thermal conditions (TJ ≤ 150°C). |
| Reference Voltage | 0.8 V ±1.0% at 25°C - enables precise output regulation; used with external resistor divider to set VOUT from 0.8 V to 28 V. |
| Quiescent Current | 25 µA - minimizes standby power loss in always-on systems such as industrial controllers and sensor nodes. |
| Switching Frequency | 200 kHz to 1.1 MHz (adjustable via RT pin) - allows optimization of efficiency vs. size: lower fSW reduces switching loss; higher fSW shrinks inductor/capacitor footprint. |
| Min On-Time | 75 ns typical - supports high VIN-to-VOUT conversion ratios (e.g., 24 V → 3.3 V) without requiring frequency foldback. |
| Thermal Shutdown | 160°C shutdown / 140°C recovery - protects against sustained overload or poor heatsinking while allowing automatic recovery after cooling. |
Pinout & Package
LMR51450FNDRRR is housed in a thermally enhanced 12-pin WSON package (DRR), 3.00 mm × 3.00 mm, with exposed thermal pad (PGND/DAP) for efficient PCB heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (1,2,3) | Power switch node | Connects to inductor; internally ties high-side FET source and low-side FET drain-requires low-inductance layout to minimize ringing and EMI. |
| BOOT (4) | Bootstrap supply | Drives high-side gate; requires 100-nF ceramic capacitor between BOOT and SW to sustain gate drive during high-side conduction. |
| PG (5) | Open-drain power-good | Asserts low when FB voltage deviates >12% above or >10% below target; needs 10–100 kΩ pullup to logic rail ≤20 V for system reset coordination. |
| RT (6) | Frequency setting | Resistor from RT to AGND sets fSW; open = ~500 kHz, short to GND = 1 MHz-enables design flexibility without changing IC. |
| FB (7) | Voltage feedback input | Senses output via resistor divider; 0.8 V reference enables accurate regulation; never short to ground during operation. |
| AGND (8) | Analog ground reference | Zero-volt reference for internal references and control logic; must be tied to PGND via small net-tie to avoid noise coupling. |
| EN (9) | Precision enable | Active-high control: 1.1–1.4 V turn-on threshold; supports external UVLO using resistor divider between VIN, EN, and AGND. |
| VIN (10,11,12) | Main input supply | Accepts 4–36 V; multiple pins reduce trace resistance and improve current handling-connect input capacitors directly here to PGND. |
| PGND/DAP (13) | Power ground & thermal pad | Internal connection to low-side FET source and exposed DAP; must be soldered to large PCB copper area for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Forced PWM (FPWM) mode | Ensures constant switching frequency and minimal output voltage ripple across entire load range-including light loads-critical for noise-sensitive analog or RF subsystems. |
| Integrated synchronous rectification | Eliminates need for external Schottky diode; reduces conduction losses and improves full-load efficiency by up to 5% versus asynchronous designs. |
| Internal compensation | Removes requirement for external Type-II/III compensation network-reduces BOM count, layout complexity, and tuning effort while maintaining stability with common output capacitors. |
| Hiccup-mode short-circuit protection | Shuts down on sustained overload, then auto-retries after 96 ms; prevents thermal runaway and enables safe recovery without manual reset. |
| Low dropout operation | Maintains regulation even when VIN approaches VOUT (e.g., 5.5 V → 5 V); extends usable input range in brownout or battery-depleted conditions. |
Applications
| PLC Power Supply | Test Instrumentation |
|---|---|
|
Use Scenario: Providing clean, regulated 5 V or 3.3 V rails for microcontrollers, I/O drivers, and analog front-ends in modular programmable logic controllers operating from 24 V industrial bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering 5 A continuous current with FPWM mode ensuring low-noise, ripple-free supply for ADC references and clock circuits. Use Value: Enables compact, fanless enclosure design with 92%+ efficiency at 2 A and thermal shutdown protection during field wiring faults. |
Use Scenario: Generating stable bias voltages for precision op-amps, DACs, and signal chain components in benchtop multimeters and oscilloscope front-ends. IC Role / Device Role / Timing Role: High-accuracy, low-drift DC/DC stage with ±1.0% reference and internal soft-start (3.2–7.2 ms) preventing inrush-induced measurement glitches. Use Value: Delivers <15 mVpp output ripple at full load and supports fast transient response (<10 µs) to maintain signal integrity during dynamic test sequences. |
| Major Appliances | Industrial Power Delivery |
|
Use Scenario: Powering motor control MCU, display interface, and sensor hubs in refrigerators, washing machines, and HVAC systems with 12 V or 24 V battery/bus input. IC Role / Device Role / Timing Role: Main system PMIC providing isolated 3.3 V and 5 V rails; uses precision EN pin for coordinated startup sequencing with main AC-DC stage. Use Value: Withstands automotive-grade transients (38 V abs max) and operates reliably from –40°C to 150°C junction temperature in sealed, high-humidity environments. |
Use Scenario: Serving as intermediate step-down stage in distributed power architecture-converting 24 V or 36 V backplane to 5 V/3.3 V for FPGA, Ethernet PHY, and memory modules. IC Role / Device Role / Timing Role: High-current, high-efficiency point-of-load regulator with PGOOD signaling to upstream supervisor IC for fault propagation and system-level diagnostics. Use Value: Supports hot-swap compliance via controlled soft-start and provides real-time status monitoring through open-drain PGOOD with glitch filtering (35 µs rejection window). |
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 | Same 5-A rating and WSON-12 package, but PFM variant with spread-spectrum capability-higher light-load efficiency but variable frequency and increased output ripple. | Better suited for battery-powered or energy-harvesting systems where ultra-low IQ dominates design priority over EMI or analog noise. | Select LMR51450SDRRR only if light-load efficiency >90% at 1 mA is required and frequency jitter is acceptable. |
| LMR50410RPER | 4-V to 65-V input, 1-A output, 12-pin WQFN; lacks FPWM mode, higher RDS(on) (120/70 mΩ), no spread spectrum, but wider VIN range and smaller solution size. | Targets high-input-voltage applications like solar charge controllers or 48 V telecom-unsuitable for 5-A industrial loads. | Choose LMR50410RPER only when input exceeds 36 V and output current ≤1 A; not a functional substitute for LMR51450FNDRRR's 5-A FPWM capability. |
Compared with LMR51450SDRRR, LMR51450FNDRRR trades light-load efficiency for predictable EMI profile and tighter output regulation; compared with LMR50410RPER, it delivers 5× more current and superior thermal performance in the same footprint-but cannot operate above 36 V input.
Availability
LMR51450FNDRRR is available at Aetrix Electronics and suitable for industrial automation, test equipment, and home appliance power systems requiring stable component supply, long-term manufacturability, and automotive-grade reliability.
Supply support for LMR51450FNDRRR 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 technologies, with decades of expertise in high-reliability industrial and automotive power solutions.
The LMR514x0 product line was designed specifically for rugged industrial DC/DC conversion-emphasizing wide input range, integrated protection, ease of use, and thermal robustness in space-constrained applications.
FAQ
What is the switching frequency range of the LMR51450FNDRRR?
The LMR51450FNDRRR supports an adjustable switching frequency from 200 kHz to 1.1 MHz, set externally via a resistor between the RT pin and AGND. Open-circuit RT defaults to ~500 kHz; shorting RT to ground sets frequency to 1 MHz. This range allows trade-offs between efficiency (lower fSW) and component size (higher fSW). The LMR51450FNDRRR operates in forced PWM (FPWM) mode, ensuring constant frequency across all load conditions.
Does the LMR51450FNDRRR support adjustable output voltage?
Yes, the LMR51450FNDRRR supports fully adjustable output voltage from 0.8 V to 28 V using an external resistor divider connected to the FB pin. Its precision 0.8 V ±1.0% internal reference enables tight regulation; TI recommends 1% tolerance, low-TC resistors with RFBB selected for desired divider current and RFBT calculated per VOUT = 0.8 × (1 + RFBT/RFBB). The LMR51450FNDRRR does not require external compensation components due to its internally compensated architecture.
How does the enable (EN) pin function on the LMR51450FNDRRR?
The EN pin on the LMR51450FNDRRR is a precision enable input with defined thresholds: device turns on when EN voltage exceeds 1.1–1.4 V and shuts down when EN falls below 0.8–1.12 V. It can be tied directly to VIN for self-startup or configured with an external resistor divider to implement programmable input UVLO-for example, to hold off startup until VIN reaches 18 V. The LMR51450FNDRRR EN pin must never be left floating and accepts voltages up to VIN + 0.3 V.
What protection features are built into the LMR51450FNDRRR?
The LMR51450FNDRRR includes cycle-by-cycle current limiting (6.4–9.6 A high-side), hiccup-mode short-circuit protection with 96 ms retry interval, thermal shutdown at 160°C (recovering at 140°C), VIN undervoltage lockout (3.9 V rising / 3.4 V falling), and BOOT-SW UVLO (2.2 V). These protections operate independently of external circuitry and ensure safe operation during fault conditions without requiring additional discrete components. The LMR51450FNDRRR also features low-dropout mode for extended regulation near VIN = VOUT.
Is the LMR51450FNDRRR pin-compatible with other devices in the LMR514x0 family?
Yes, the LMR51450FNDRRR shares the same 12-pin WSON-12 (DRR) package and pinout with other LMR514x0 variants-including LMR51440SDRRR and LMR51450SDRRR-enabling direct substitution within the same footprint. However, functional differences exist: LMR51450FNDRRR uses FPWM mode (constant frequency), while SDRRR variants use PFM mode (variable frequency). Board-level changes may be needed for RT resistor value or feedback divider to match target VOUT and fSW requirements.
LMR51450FNDRRR 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:
- 5A
- 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)
LMR51450FNDRRR FAQ
1.How can I place an order for LMR51450FNDRRR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMR51450FNDRRR 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 LMR51450FNDRRR reliable?
The price and inventory of LMR51450FNDRRR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMR51450FNDRRR is usually 5 days.
3.What payment methods are accepted for LMR51450FNDRRR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMR51450FNDRRR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMR51450FNDRRR?
LMR51450FNDRRR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMR51450FNDRRR 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 LMR51450FNDRRR?
For technical support, including LMR51450FNDRRR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMR51450FNDRRR requirements.
6.How does Aetrix verify that LMR51450FNDRRR is sourced from the original manufacturer or authorized distributors?
All LMR51450FNDRRR 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 LMR51450FNDRRR meets industry standards.
7.What is the process for return or replacement of LMR51450FNDRRR?
All LMR51450FNDRRR units undergo pre-shipment inspection (PSI). If there is an issue with LMR51450FNDRRR, 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 LMR51450FNDRRR part is unused and in its original packaging.
Return procedure for LMR51450FNDRRR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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