Texas Instruments LMQ66410R5RXBR

Overview

LMQ66410R5RXBR from Texas Instruments is a 36V, 1A synchronous step-down DC/DC converter with integrated VIN bypass and CBOOT capacitors in an enhanced HotRod QFN-FCRLF package. It delivers fixed 5V output, supports 2.7V–36V input after startup, features adjustable switching frequency (200kHz–2.2MHz), achieves ≥85% efficiency at 1mA, and operates across –40°C to +150°C junction temperature for industrial power rails.

For engineers reviewing the LMQ66410R5RXBR datasheet, LMQ66410R5RXBR pinout, LMQ66410R5RXBR application, or LMQ66410R5RXBR equivalent, this page provides verified technical context, validated pin functions, confirmed EMI-reduction features (dual-random spread spectrum, integrated capacitors), real-world thermal performance (R_θJA = 66.1°C/W), and direct alternative part comparisons for PLC, medical, and test equipment designs.

Technical Context

The LMQ66410R5RXBR implements peak-current-mode control with auto mode enabling frequency foldback below 1mA load, achieving 1.5µA no-load quiescent current at 13.5V_IN. Its ZEN 2 switcher architecture integrates two 22-nF VIN bypass capacitors and a 0.1-µF CBOOT capacitor internally, eliminating external placement while reducing high-frequency EMI.

It uses dual-random spread spectrum (DRSS) modulation and an optimized HotRod QFN-FCRLF pinout-featuring NC pins between critical high-voltage nodes-to suppress peak emissions and improve FMEA robustness. The RT pin enables precise frequency tuning from 200kHz to 2.2MHz, avoiding noise-sensitive bands without requiring external clock synchronization.

Key Specifications

Pinout & Package

LMQ66410R5RXBR uses the RXB package: enhanced HotRod™ VQFN-FCRLF with 14 pins, 2.6 mm × 2.6 mm footprint, wettable flanks, and exposed thermal pad (GND/DAP) requiring solder connection to system ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck converter applications.

Compared with LMQ66420R5RXBR, the LMQ66410R5RXBR reduces conduction losses at light loads and lowers thermal stress in space-constrained enclosures; versus TPS543320RHLR, it delivers superior EMI performance and smaller total solution size despite narrower input range.

Availability

LMQ66410R5RXBR is available at Aetrix Electronics and suitable for factory automation, medical instrumentation, and test equipment requiring stable component supply, long-term industrial lifecycle support, and guaranteed availability through 2030.

Supply support for LMQ66410R5RXBR 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 over 50 years of innovation in industrial-grade power solutions.

The LMQ664x0 family was designed specifically for ultra-compact, low-EMI industrial DC/DC conversion - targeting PLCs, medical devices, and aerospace systems needing high reliability, wide input range, and minimal external components.

FAQ

What is the maximum input voltage the LMQ66410R5RXBR can withstand without damage?

The LMQ66410R5RXBR has an absolute maximum VIN-to-GND rating of 42 V, meaning it can survive short-duration transients up to that level without permanent damage. However, normal operation is specified from 2.7 V to 36 V after startup. Sustained operation above 36 V is not recommended, and the device enters protection modes if internal limits are exceeded. This 42 V rating supports robustness in industrial 24 V and 36 V bus systems with load-dump events.

Does the LMQ66410R5RXBR require external input or bootstrap capacitors?

No, the LMQ66410R5RXBR does not require external input bypass or bootstrap capacitors. It integrates two 22-nF capacitors in series from VIN to PGND and a 0.1-µF capacitor from BOOT to SW internally. These eliminate three external passive components, reduce EMI filter complexity, and shrink total solution size. External high-quality ceramic input capacitance may still be added for low-frequency bulk filtering if required by system-level ripple specs.

How does the LMQ66410R5RXBR achieve low EMI performance?

The LMQ66410R5RXBR achieves low EMI through three integrated techniques: dual-random spread spectrum (DRSS) modulation to smear switching energy across a wider frequency band, an enhanced HotRod QFN-FCRLF package with no bond wires to minimize switch-node ringing, and internal VIN bypass and CBOOT capacitors to suppress high-frequency noise at the source. Together, these features meet CISPR 32 Class B limits without external shielding or common-mode chokes in typical layouts.

What is the purpose of the NC pins on the LMQ66410R5RXBR package?

The NC (no-connect) pins on the LMQ66410R5RXBR - specifically pins 2, 4, 5, 9, and 12 - serve a functional reliability role: they are placed between critical high-voltage nodes (e.g., VIN, SW, BOOT) to increase creepage and clearance distances. This physical separation reduces risk of surface tracking, arcing, or latent failures under high humidity or contamination - a key part of TI's pin-level FMEA analysis for industrial applications.

Can the LMQ66410R5RXBR operate with zero load, and what is its quiescent current?

Yes, the LMQ66410R5RXBR supports true zero-load operation in Auto mode, drawing only 1.5 µA typical input current at 13.5 V_IN and 25°C. This ultra-low quiescent current is maintained across the full –40°C to +150°C junction temperature range, making it ideal for always-on industrial systems where standby power must be minimized without sacrificing start-up speed or regulation accuracy.