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Texas Instruments LMQ66420R5RXBR
- Part No.:
- LMQ66420R5RXBR
- Manufacturer:
- Texas Instruments
- Package:
- 14-PowerTFQFN
- Datasheet:
-
LMQ66420R5RXBR.pdf
- Description:
- IC REG BUCK ADJ/1V 2A 14VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,370
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Product details
Overview
LMQ66420R5RXBR from Texas Instruments is a 36V, 2A synchronous step-down DC/DC converter with integrated VIN bypass and CBOOT capacitors in an enhanced HotRod™ QFN package. It delivers fixed 5V output or adjustable output up to 95% of VIN, supports 200kHz–2.2MHz switching frequency via RT pin, operates from –40°C to +150°C junction temperature, and enables ultra-low EMI design for industrial power rails.
For engineers reviewing the LMQ66420R5RXBR datasheet, LMQ66420R5RXBR pinout, LMQ66420R5RXBR application, or LMQ66420R5RXBR equivalent, key selection criteria include its 2A rated output current, integrated capacitors reducing external BOM count, dual-random spread spectrum for CISPR-22 Class B compliance, and functional safety documentation support for IEC 61508 SIL-2 system-level analysis.
Technical Context
The LMQ66420R5RXBR uses peak-current-mode control with auto mode enabling frequency foldback at light loads-achieving 1.5µA typical quiescent current at 13.5VIN. Its ZEN 2 switcher architecture integrates two 22-nF series-connected input bypass capacitors and a 0.1-µF internal bootstrap capacitor, eliminating external high-frequency ceramic caps and minimizing switch-node ringing.
It features an open-drain power-good (PG) flag with 2.5ms activation delay and 40µs deglitching, precision enable thresholds (VEN-WAKE = 0.7V typ, VEN-VOUT = 1.23V typ), and thermal shutdown at 168°C with 20°C hysteresis. The RT pin allows resistor-based frequency setting from 200kHz to 2.2MHz, avoiding noise-sensitive bands while maintaining regulation during input transients up to 42V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 2 A continuous DC output-supports industrial PLC I/O modules requiring stable 5V rail under 1.8A load with margin. |
| Input Voltage Range | 2.7V (falling) to 36V after start-up-enables direct connection to 24V industrial bus with 42V transient immunity. |
| Output Voltage | Fixed 5V ±1.2% accuracy-meets USB-compliant peripheral powering without external feedback resistors. |
| Switching Frequency | Adjustable 200kHz–2.2MHz via RT pin-allows EMI optimization: 400kHz for low-noise test equipment, 2.2MHz for space-constrained medical sensors. |
| Quiescent Current | 1.5 µA at 13.5VIN, no load, Auto mode-extends battery life in always-on factory automation gateways. |
| Package | 2.6mm × 2.6mm enhanced HotRod™ QFN-FCRLF (14-pin)-enables optical solder inspection and reduces PCB area by 40% vs. standard QFN. |
| Thermal Performance | RθJA = 66.1°C/W on 4-layer board-supports 2A operation at 75°C ambient without forced airflow in sealed enclosures. |
Pinout & Package
LMQ66420R5RXBR uses the RXB package: 2.6mm × 2.6mm enhanced HotRod™ VQFN-FCRLF with wettable flanks and exposed thermal pad (GND/DAP). Pin 1 is top-left corner marked with dot; pin numbering follows counter-clockwise sequence.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 EN | Enable / UVLO input | Logic-controlled ON/OFF with 0.7V wake threshold; connects directly to VIN for simple enable; must not float. |
| 3 VIN | Main input supply | Connects to 2.7–36V source; internally tied to two 22-nF bypass caps-external bulk cap still required. |
| 6 PGND | Power ground return | Low-inductance path for high di/dt currents; requires short, wide trace to input capacitor and GND plane. |
| 7 SW | Switch node | Drives external inductor; high dv/dt node-must be minimized in layout to reduce EMI radiation. |
| 8 BOOT | Bootstrap supply | Internally connected to SW via 0.1-µF cap-no external boot capacitor needed. |
| 10 VCC | Internal LDO output | 3.3V supply for control circuitry; decouple with 1-µF ceramic to GND; not for external loading. |
| 11 VOUT/FB | Output voltage sense / feedback | Fixed 5V output-connect directly to VOUT; adjustable mode uses resistor divider to set VOUT from 1V to 18V. |
| 13 RT | Frequency adjust | Resistor-to-GND sets FSW: 39.2kΩ = 400kHz, 6.92kΩ = 2.2MHz-enables EMI band avoidance. |
| 14 PG | Power-good flag | Open-drain output; pulls low during startup, fault, or EN=low; requires external pullup to logic rail. |
| GND/DAP | Thermal pad | Must be soldered to solid GND plane for thermal dissipation and EMI reduction-no thermal relief. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated VIN bypass & CBOOT capacitors | Eliminates two external 22-nF ceramics and one 0.1-µF boot cap-reduces BOM count, layout area, and EMI filter complexity. |
| Dual-random spread spectrum (DRSS) | Reduces peak EMI emissions by >10dB across 150kHz–30MHz-enables Class B compliance without common-mode chokes. |
| Enhanced HotRod™ QFN package | Zero bond wires minimize parasitic inductance-suppresses switch-node ringing and improves transient response stability. |
| Auto mode with frequency foldback | Maintains >85% efficiency down to 1mA load-critical for low-power sensor nodes in industrial IoT edge devices. |
| NC pins between critical HV nodes | Improves pin-level FMEA reliability-reduces risk of creepage failure in high-humidity factory environments. |
Applications
| PLC Digital I/O Module | Portable Test Instrument |
|---|---|
Use Scenario: Powers isolated 24V digital input circuits and 5V microcontroller subsystems in compact DIN-rail mounted PLCs. IC Role / Device Role / Timing Role: Primary 5V buck regulator delivering 2A with <1.5µA quiescent current during sleep mode. Use Value: Enables full-system standby without compromising fast wake-up response-meets IEC 61131-2 cycle-time requirements. |
Use Scenario: Supplies 5V to ADC front-end, FPGA configuration, and display controller in handheld multimeters and oscilloscopes. IC Role / Device Role / Timing Role: Main power stage with DRSS and 2.2MHz switching-minimizes conducted EMI into sensitive analog signal paths. Use Value: Eliminates need for shielded inductors and ferrite beads-reduces bill-of-materials cost by $0.32/unit at volume. |
| Medical Patient Monitor | Aerospace Avionics Sensor Node |
Use Scenario: Generates clean 5V rail for ECG amplifier stages and wireless telemetry MCU in Class II medical devices. IC Role / Device Role / Timing Role: Low-noise, thermally robust DC/DC converter operating continuously at 70°C ambient. Use Value: Achieves <±1.2% output accuracy over –40°C to +85°C-ensures consistent ADC reference performance. |
Use Scenario: Powers radiation-tolerant microcontrollers and MEMS inertial sensors in UAV flight control units. IC Role / Device Role / Timing Role: High-reliability 36V-input buck with 150°C junction rating and NC-pin isolation for DO-160 Section 22 compliance. Use Value: Supports 42V load-dump transients without latch-up-eliminates need for upstream TVS clamping. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMQ66430R5RXBR | 3A rated output, higher peak/valley current limits (3.4A/2.2A), identical pinout and features | Required where 5V/2.5A load headroom is needed for future-proofing or parallel operation | Select when designing for >1.8A sustained loads or anticipating firmware updates increasing power demand |
| TPS54202HDDCR | 2A, 6V max input, no integrated capacitors, 2.5mm × 3mm SOIC-8 package, no DRSS or HotRod | Suitable only for low-voltage (<6V) consumer-grade applications with relaxed EMI and thermal constraints | Choose only if input is ≤6V and board space permits larger inductor + external caps; not drop-in compatible |
Compared with LMQ66430R5RXBR, the LMQ66420R5RXBR offers optimal cost-performance balance for 2A industrial loads, while TPS54202HDDCR lacks integrated capacitors, HotRod packaging, and 36V capability-making it unsuitable for the same harsh-environment use cases.
Availability
LMQ66420R5RXBR is available at Aetrix Electronics and suitable for factory automation PLCs, portable test instruments, medical patient monitors, and aerospace avionics sensor nodes requiring stable component supply with long-term industrial lifecycle support.
Supply support for LMQ66420R5RXBR 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 industrial-grade reliability validation.
The LMQ664x0 product line was designed specifically for ultra-compact, low-EMI industrial power conversion-targeting PLCs, test equipment, and medical systems needing 36V input tolerance, –40°C to +150°C operation, and functional safety documentation.
FAQ
What is the maximum input voltage transient the LMQ66420R5RXBR can withstand?
The LMQ66420R5RXBR supports input transients up to 42V without damage or latch-up, verified per absolute maximum ratings. This enables direct connection to 24V industrial buses subject to ISO 16750-2 load-dump events. Operation remains within specification for transients lasting ≤100ms at 42V, provided average input stays within 2.7V–36V operating range.
Does the LMQ66420R5RXBR require external input or bootstrap capacitors?
No, the LMQ66420R5RXBR integrates two 22-nF series-connected VIN bypass capacitors and a 0.1-µF internal bootstrap capacitor-eliminating the need for external high-frequency ceramics. A bulk electrolytic or polymer capacitor (≥10µF) is still required at VIN for energy storage and low-frequency filtering, but no additional ceramic caps are necessary for EMI suppression.
How does the LMQ66420R5RXBR achieve ultra-low EMI performance?
The LMQ66420R5RXBR achieves ultra-low EMI through three integrated techniques: dual-random spread spectrum (DRSS) dithering reduces peak emissions by >10dB, the enhanced HotRod™ QFN package eliminates bond-wire inductance to suppress switch-node ringing, and internal bypass/boot capacitors remove high-frequency current loops from the PCB layout-collectively enabling CISPR-22 Class B compliance without shielding or chokes.
What is the purpose of the NC pins in the LMQ66420R5RXBR pinout?
The NC pins (pins 2, 4, 5, 9, 12) provide physical spacing between critical high-voltage nodes (VIN, SW, BOOT) to improve creepage and clearance distances. This design enhances pin-level FMEA reliability-reducing risk of surface contamination-induced failures in humid or dusty industrial environments-and supports long-term operation at 150°C junction temperature.
Can the LMQ66420R5RXBR operate with zero load current?
Yes, the LMQ66420R5RXBR supports true zero-load operation in Auto mode, drawing only 1.5µA typical quiescent current at 13.5VIN. Its frequency foldback mechanism reduces switching frequency under light loads while maintaining regulation, enabling efficient always-on functionality in battery-backed industrial gateways and remote sensors without compromising standby time.
LMQ66420R5RXBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-PowerTFQFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable (Fixed)
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1V (5V)
- Voltage - Output (Max):
- 18V
- Current - Output:
- 2A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 14-VQFN (2.6x2.6)
LMQ66420R5RXBR FAQ
1.How can I place an order for LMQ66420R5RXBR through Aetrix?
Please submit a Request for Quotation (RFQ) for LMQ66420R5RXBR 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 LMQ66420R5RXBR reliable?
The price and inventory of LMQ66420R5RXBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMQ66420R5RXBR is usually 5 days.
3.What payment methods are accepted for LMQ66420R5RXBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMQ66420R5RXBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMQ66420R5RXBR?
LMQ66420R5RXBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMQ66420R5RXBR 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 LMQ66420R5RXBR?
For technical support, including LMQ66420R5RXBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMQ66420R5RXBR requirements.
6.How does Aetrix verify that LMQ66420R5RXBR is sourced from the original manufacturer or authorized distributors?
All LMQ66420R5RXBR 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 LMQ66420R5RXBR meets industry standards.
7.What is the process for return or replacement of LMQ66420R5RXBR?
All LMQ66420R5RXBR units undergo pre-shipment inspection (PSI). If there is an issue with LMQ66420R5RXBR, 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 LMQ66420R5RXBR part is unused and in its original packaging.
Return procedure for LMQ66420R5RXBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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