Texas Instruments LMR33620AQRNXTQ1

Overview

LMR33620AQRNXTQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified synchronous step-down DC/DC converter delivering up to 2 A output current across 3.8 V–36 V input, with adjustable 1 V–24 V output, 400 kHz switching frequency, and integrated 75 mΩ/50 mΩ MOSFETs. It serves as a primary power supply for infotainment USB charging and telematics control units in harsh vehicle environments.

For engineers reviewing the LMR33620AQRNXTQ1 datasheet, LMR33620AQRNXTQ1 pinout, LMR33620AQRNXTQ1 application, or LMR33620AQRNXTQ1 equivalent, key selection criteria include its 68 ns minimum on-time, 25 µA operating quiescent current, thermal shutdown protection, precision enable threshold (1.231 V typ), and wettable-flank 3 mm × 2 mm VQFN package optimized for EMI-sensitive automotive layouts.

Technical Context

The LMR33620AQRNXTQ1 implements peak-current-mode control with automatic PFM/PWM mode transition at light loads to sustain >95% peak efficiency. Its internal compensation network eliminates external loop components, while the 1.0 V feedback reference enables precise output regulation across temperature (±1.5% over –40°C to +125°C).

It features cycle-by-cycle current limiting, hiccup-mode short-circuit protection triggered at FB < 0.4 V, and a dedicated open-drain power-good flag with 60–170 µs glitch filtering. The BOOT-to-SW bootstrap circuit supports high-side gate drive with 100 nF capacitor, and VIN/PGND symmetry reduces magnetic field coupling for low EMI.

Key Specifications

Pinout & Package

LMR33620AQRNXTQ1 uses a 12-pin VQFN (RNX) package measuring 3.00 mm × 2.00 mm × 0.85 mm with wettable flanks for automated optical inspection (AOI) and enhanced thermal performance via exposed PGND pad.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33620BQRNXTQ1, the LMR33620AQRNXTQ1 offers lower EMI and reduced inductor size trade-offs at 400 kHz, while the TPS543320RTWR provides higher current but lacks automotive qualification-making LMR33620AQRNXTQ1 the sole AEC-Q100-compliant 2-A 400-kHz option in this footprint.

Availability

LMR33620AQRNXTQ1 is available at Aetrix Electronics and suitable for automotive infotainment, telematics control units, and ADAS camera modules requiring stable component supply, long-term lifecycle assurance, and AEC-Q100 compliance.

Supply support for LMR33620AQRNXTQ1 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 and embedded processing technologies, with decades of automotive-grade power management innovation.

The LMR33620AQRNXTQ1 belongs to TI's automotive-qualified SIMPLE SWITCHER® DC/DC converter family, designed specifically for robust, low-EMI, high-efficiency power conversion in demanding vehicle environments-from infotainment to domain controllers.

FAQ

What is the maximum input voltage rating for the LMR33620AQRNXTQ1?

The LMR33620AQRNXTQ1 has an absolute maximum input voltage rating of 38 V, with recommended operation from 3.8 V to 36 V. This range accommodates automotive battery transients including load dump (up to 36 V) and cold-crank (down to 3.8 V), ensuring reliable operation across all vehicle operating conditions. The device remains functional at 36 V input while delivering full 2-A output.

Does the LMR33620AQRNXTQ1 require external compensation components?

No, the LMR33620AQRNXTQ1 integrates a complete Type II compensation network internally. This eliminates the need for external resistors and capacitors typically required for loop stability, reducing design complexity, BOM count, and PCB area. The internal compensation is optimized for standard 2.2-µH inductors and 22-µF output capacitors across the full input/output range.

How does the power-good (PG) flag behave during startup of the LMR33620AQRNXTQ1?

The LMR33620AQRNXTQ1's PG flag remains low for approximately 4 ms after EN is asserted, then transitions high once VOUT reaches 95% of target and remains stable for ≥170 µs. During normal operation, PG pulls low if VOUT falls outside ±5% window or during faults like thermal shutdown or current limit. When EN is low, PG is forced low regardless of output condition.

What is the purpose of the NC pin (Pin 3) on the LMR33620AQRNXTQ1 VQFN package?

Pin 3 (NC) on the LMR33620AQRNXTQ1 has no internal connection but is used on the PCB to route the CBOOT capacitor to the SW pin. This layout technique minimizes the loop area and parasitic inductance of the bootstrap path-critical for stable high-side gate drive and reduced switching noise. TI's reference design places the CBOOT capacitor directly between NC and SW pins.

Can the LMR33620AQRNXTQ1 operate in dropout condition, and what happens to regulation?

Yes, the LMR33620AQRNXTQ1 operates in dropout when VIN approaches VOUT (e.g., 5.5 V input for 5 V output). In this mode, it extends duty cycle to ~98% and reduces switching frequency to maintain regulation. Dropout voltage is specified as 150 mV at 1 A load. Output accuracy degrades slightly in dropout, but the device maintains regulation without collapsing-enabling graceful operation during low-battery events.