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Texas Instruments LMR51406XFDBVR
- Part No.:
- LMR51406XFDBVR
- Manufacturer:
- Texas Instruments
- Package:
- SOT-23-6
- Datasheet:
-
LMR51406XFDBVR.pdf
- Description:
- IC REG BUCK ADJ 600MA SOT23-6
- Quantity:
- Payment:
- Shipping:
Inventory:2,940
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Product details
Overview
LMR51406XFDBVR from Texas Instruments is a 400kHz fixed-frequency synchronous buck converter in SOT-23-6 package, delivering up to 0.6A output current with 4V–42V input range, ±1.5% reference voltage accuracy, and FPWM operation for constant-frequency, low-ripple regulation in industrial power rails.
For engineers reviewing the LMR51406XFDBVR datasheet, LMR51406XFDBVR pinout, LMR51406XFDBVR application, or LMR51406XFDBVR equivalent, key selection criteria include its 80ns minimum on-time, hiccup-mode short-circuit protection, precision enable with adjustable UVLO, thermal shutdown at 165°C, and compatibility with compact 2.9mm × 2.8mm PCB layouts.
Technical Context
The LMR51406XFDBVR implements fixed-frequency peak-current mode control with internal compensation, enabling stable regulation using minimal external components. Its FPWM operation enforces constant 400kHz switching across full load range-eliminating frequency variation and minimizing output voltage ripple during light-load conditions.
It integrates high-side (0.7Ω) and low-side (0.36Ω) MOSFETs, uses a bootstrap capacitor (CB) for high-side gate drive, and features monotonic soft-start (2.3ms), cycle-by-cycle current limiting, and hiccup-mode recovery for sustained overloads. Input transient tolerance reaches 50V, supporting rugged industrial environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 42V - supports wide-input industrial supplies including 24V DC rails and unregulated battery-derived sources. |
| Output Current | 0.6A continuous - sufficient for powering microcontrollers, sensors, and I/O peripherals in PLC and smart meter applications. |
| Switching Frequency | 400kHz (fixed, FPWM) - enables use of small, low-profile inductors while maintaining tight output regulation and predictable EMI profile. |
| Reference Voltage | 0.8V ±1.5% - ensures accurate adjustable output voltage setting (e.g., 3.3V, 5V, 12V) across –40°C to +150°C junction temperature. |
| Min ON Time | 80ns - allows high step-down ratios (e.g., 42V→3.3V) without frequency foldback at light loads, preserving regulation integrity. |
| Thermal Shutdown | 165°C with 20°C hysteresis - protects against thermal runaway in enclosed enclosures or high ambient temperature deployments. |
| Enable Threshold | 1.227V (rising), 1.0V (falling) - enables precise system-level UVLO via resistor divider, critical for battery-powered or utility-tied equipment. |
Pinout & Package
SOT-23-6 (DBV) package: 2.90mm × 2.80mm footprint, thermally enhanced for 0.6A operation in space-constrained industrial modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CB | Bootstrap capacitor connection | Connects 100nF ceramic capacitor to SW; supplies gate drive voltage for integrated high-side MOSFET. |
| GND | Power ground | Common return for internal low-side FET source, CIN, and COUT; requires shortest possible trace to minimize noise and improve stability. |
| FB | Feedback input | Monitors output voltage via resistor divider; sets regulated VOUT = 0.8V × (1 + RFBT/RFBB); must not be shorted to GND. |
| EN | Precision enable | Logic-controlled startup/shutdown; 1.227V threshold enables operation; supports external UVLO configuration with resistor divider. |
| VIN | Input supply | Connects to 4V–42V source and input bypass capacitors; powers internal bias LDO and high-side driver; withstands 50V transients. |
| SW | Switch node | Drives external power inductor; connects internally to source of high-side FET and drain of low-side FET; high dv/dt node requiring careful layout. |
Key Features
| Feature | Design Value |
|---|---|
| FPWM operation | Enables constant 400kHz switching across 0–0.6A load range-reducing output voltage ripple and simplifying EMI filtering vs. PFM variants. |
| Integrated synchronous rectification | Eliminates need for external catch diode; improves efficiency by ~5–10% at mid-to-high loads compared to asynchronous buck topologies. |
| Internal compensation | Reduces BOM count and design time-only FB divider, input/output capacitors, inductor, and CB capacitor required for functional operation. |
| Hiccup-mode short-circuit protection | Shuts down for 150ms upon sustained overload, then retries-limits average power dissipation and prevents thermal damage during fault conditions. |
| Monotonic start-up with prebiased output | Ensures controlled voltage ramp even when output is precharged (e.g., hot-swap or backup rail scenarios), avoiding reverse current or latch-up. |
Applications
| PLC Digital I/O Power | Smart Meter MCU Supply |
|---|---|
|
Use Scenario: Powers isolated digital input/output modules in programmable logic controllers operating from 24V DC field bus. IC Role / Device Role / Timing Role: Primary 3.3V/5V point-of-load regulator converting noisy 24V industrial rail to clean, regulated MCU and interface IC supply. Use Value: 400kHz FPWM operation suppresses low-frequency ripple that could interfere with analog sensing or communication interfaces (RS-485, CAN). |
Use Scenario: Supplies main application processor and metrology ASIC in residential/commercial smart meters powered from AC-DC or battery backup. IC Role / Device Role / Timing Role: Adjustable-output buck converter delivering 1.2V core and 3.3V I/O rails with tight regulation under varying load and temperature. Use Value: ±1.5% reference accuracy and –40°C to +150°C operation ensure metrology-grade timing and ADC performance across environmental extremes. |
| Industrial Sensor Node | DC Power Delivery Module |
|
Use Scenario: Powers wireless sensor nodes (LoRaWAN, NB-IoT) deployed in factory automation with wide-input 12–36V DC distribution. IC Role / Device Role / Timing Role: Compact, rugged DC-DC stage stepping down variable input to stable 3.3V for RF SoC and analog front-end. Use Value: 80ns min-on-time and 50V transient tolerance allow reliable operation during motor switching noise or cable surge events. |
Use Scenario: Embedded power module in DIN-rail mounted power supplies delivering auxiliary 5V/0.6A for control logic and HMI backlighting. IC Role / Device Role / Timing Role: Secondary-stage synchronous buck providing isolated, low-noise auxiliary rail decoupled from primary flyback output. Use Value: SOT-23-6 footprint and internal MOSFETs reduce board area by >40% vs. discrete solutions-critical for space-limited DIN-rail enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMR51406XDBVR | Same 0.6A/400kHz rating but PFM mode-higher light-load efficiency, variable frequency, larger output ripple. | Better suited for battery-powered devices where standby current matters more than ripple or EMI predictability. | Select LMR51406XDBVR only if light-load efficiency dominates over output stability and EMI control. |
| LMR51410XFDBVR | 1A output current, identical FPWM mode and pinout-same layout, higher thermal stress at full load. | Required when system load exceeds 0.6A (e.g., multi-rail designs with FPGA or Ethernet PHYs). | Use LMR51410XFDBVR when future-proofing for higher current or sharing layout with 1A variants-no PCB change needed. |
Compared with LMR51406XFDBVR, the LMR51406XDBVR trades constant-frequency operation for improved light-load efficiency, while the LMR51410XFDBVR maintains identical FPWM behavior but doubles output capability-enabling scalable design reuse without layout revision.
Availability
LMR51406XFDBVR is available at Aetrix Electronics and suitable for industrial automation, smart metering, and sensor node power conversion requiring stable component supply, long-term lifecycle support, and automotive-grade reliability validation.
Supply support for LMR51406XFDBVR 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 industrial-grade product development and manufacturing excellence.
The LMR514xx family was designed specifically for rugged, space-constrained industrial power conversion-emphasizing wide VIN range, high temperature operation, and ease of use through integrated FETs and internal compensation.
FAQ
What is the maximum input voltage the LMR51406XFDBVR can withstand during transients?
The LMR51406XFDBVR supports input transients up to 50V for durations under 10ns, as specified in its Absolute Maximum Ratings. This transient tolerance enables robust operation in industrial environments with inductive load switching or cable surge events-without requiring external TVS clamping in many cases. The device remains fully functional within its 4V–42V recommended operating range.
Does the LMR51406XFDBVR require an external bootstrap capacitor?
Yes, the LMR51406XFDBVR requires a 100nF ceramic capacitor (X7R/X5R, ≥16V rating) between the CB and SW pins to generate the gate drive voltage for its integrated high-side MOSFET. This bootstrap capacitor is refreshed during low-side conduction and is essential for proper high-side switching-omitting it will prevent regulation or cause erratic operation.
Can the LMR51406XFDBVR operate with a prebiased output voltage?
Yes, the LMR51406XFDBVR features monotonic start-up with prebiased output support. It safely ramps the output from an initial voltage (e.g., from a backup rail or hot-swap condition) without drawing reverse current or causing latch-up-making it suitable for redundant power systems and hot-plug applications where output capacitance may already be charged.
What is the purpose of the EN pin's precision enable function in the LMR51406XFDBVR?
The EN pin in the LMR51406XFDBVR provides precision enable control with 1.227V rising and 1.0V falling thresholds, allowing designers to implement system-level undervoltage lockout (UVLO) using an external resistor divider. This enables coordinated power sequencing, battery discharge protection, or utility-fail detection-without needing additional supervisor ICs.
How does hiccup-mode protection work in the LMR51406XFDBVR during a short circuit?
Under sustained short-circuit conditions, the LMR51406XFDBVR activates hiccup-mode protection: it shuts down for 150ms (typical), then attempts restart. If the fault persists, the cycle repeats-limiting average power dissipation and preventing thermal damage. This behavior is distinct from latch-off or current-limit-only schemes and is confirmed in the device's Electrical Characteristics table under THICCUP parameter.
LMR51406XFDBVR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- SOT-23-6
- 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):
- 42V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 28V
- Current - Output:
- 600mA
- Frequency - Switching:
- 400kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-6
LMR51406XFDBVR FAQ
1.How can I place an order for LMR51406XFDBVR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMR51406XFDBVR 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 LMR51406XFDBVR reliable?
The price and inventory of LMR51406XFDBVR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMR51406XFDBVR is usually 5 days.
3.What payment methods are accepted for LMR51406XFDBVR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMR51406XFDBVR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMR51406XFDBVR?
LMR51406XFDBVR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMR51406XFDBVR 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 LMR51406XFDBVR?
For technical support, including LMR51406XFDBVR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMR51406XFDBVR requirements.
6.How does Aetrix verify that LMR51406XFDBVR is sourced from the original manufacturer or authorized distributors?
All LMR51406XFDBVR 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 LMR51406XFDBVR meets industry standards.
7.What is the process for return or replacement of LMR51406XFDBVR?
All LMR51406XFDBVR units undergo pre-shipment inspection (PSI). If there is an issue with LMR51406XFDBVR, 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 LMR51406XFDBVR part is unused and in its original packaging.
Return procedure for LMR51406XFDBVR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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