Texas Instruments LMR33620CQ5RNXTQ1

Overview

LMR33620CQ5RNXTQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive-qualified synchronous step-down DC/DC converter delivering 2 A output current across 3.8 V to 36 V input, with fixed 5-V output, 2.1-MHz switching frequency, and integrated 75-mΩ/50-mΩ power MOSFETs. It operates in harsh vehicle environments including infotainment USB charging and telematics control units.

For engineers reviewing the LMR33620CQ5RNXTQ1 datasheet, LMR33620CQ5RNXTQ1 pinout, LMR33620CQ5RNXTQ1 application, or LMR33620CQ5RNXTQ1 equivalent, key selection criteria include its fixed 5-V output, 2.1-MHz operation for compact filter design, wettable-flank VQFN package for solder inspection, precision enable thresholds (1.231 V typical), and automotive-grade thermal shutdown at 165°C.

Technical Context

The LMR33620CQ5RNXTQ1 implements peak-current-mode control with automatic PFM/PWM mode transition to maintain >95% peak efficiency across load range. Its 68-ns minimum on-time enables high VIN-to-VOUT step-down ratios - e.g., regulating 5 V from as low as 3.8 V input - while integrated compensation eliminates external loop components.

It features a precision open-drain power-good flag (PG) with ±2% threshold hysteresis, cycle-by-cycle current limiting, hiccup-mode short-circuit protection (94-ms off-time), and thermal shutdown with 148°C recovery. The device uses internal 5-V LDO (VCC) for bias and supports logic-level enable with 100-mV hysteresis and <0.2-nA leakage.

Key Specifications

Pinout & Package

LMR33620CQ5RNXTQ1 is housed in a 12-pin VQFN (RNX) package measuring 3.0 mm × 2.0 mm × 0.85 mm with wettable flanks for automated optical inspection. The thermally enhanced layout places VIN and PGND pins symmetrically to cancel input current magnetic fields and reduce EMI.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33620BQRNX, the LMR33620CQ5RNXTQ1 achieves 30% smaller passive component size via 2.1-MHz operation; versus TPS543320RTWR, it offers lower BOM cost and simpler layout for fixed 5-V use cases without telemetry needs.

Availability

LMR33620CQ5RNXTQ1 is available at Aetrix Electronics and suitable for automotive infotainment systems, telematics control units, and ADAS camera modules requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LMR33620CQ5RNXTQ1 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 automotive-grade power management ICs with over 40 years of automotive qualification experience.

The LMR336x0-Q1 product line delivers high-efficiency, easy-to-use synchronous buck regulators optimized for automotive subsystems demanding AEC-Q100 compliance, low EMI, and minimal external components.

FAQ

What is the switching frequency of the LMR33620CQ5RNXTQ1 and why does it matter?

The LMR33620CQ5RNXTQ1 operates at a fixed 2.1 MHz. This high frequency allows use of smaller inductors (typically 1.0–1.5 µH) and ceramic output capacitors (10–22 µF), significantly reducing solution size and enabling placement in tight spaces such as behind instrument clusters. It also shifts switching noise above sensitive AM radio bands, easing EMI filtering.

Does the LMR33620CQ5RNXTQ1 require external feedback resistors for its 5-V output?

No. The LMR33620CQ5RNXTQ1 is the fixed 5-V output variant - the feedback divider is fully internal. Pin 7 (FB) is internally connected to the regulated 5-V rail, eliminating external resistors and associated tolerance errors. This simplifies layout and improves output accuracy to ±1.5% over temperature and line.

How does the LMR33620CQ5RNXTQ1 handle short-circuit conditions?

The LMR33620CQ5RNXTQ1 uses cycle-by-cycle current limiting followed by hiccup mode. When FB voltage drops below 0.4 V (indicating hard short), it shuts down for 94 ms, then attempts soft-start recovery. If the fault persists, this cycle repeats - limiting average power dissipation and junction temperature rise to protect both the LMR33620CQ5RNXTQ1 and downstream circuitry.

Can the LMR33620CQ5RNXTQ1 be used in systems requiring functional safety compliance?

Yes. The LMR33620CQ5RNXTQ1 is functional safety-capable: TI provides documentation including FMEDA reports and safety analysis guidance to support ISO 26262 ASIL-B system-level development. While the LMR33620CQ5RNXTQ1 itself is not ASIL-certified, its architecture and failure modes are documented to aid safety mechanism design.

What package type and thermal characteristics does the LMR33620CQ5RNXTQ1 use?

The LMR33620CQ5RNXTQ1 uses a 12-pin VQFN (RNX) package measuring 3.0 mm × 2.0 mm × 0.85 mm with wettable flanks. Its thermal resistance is RθJA = 72.5°C/W (JEDEC 4-layer board), RθJB = 23.3°C/W, and it features thermal shutdown at 165°C with 148°C hysteresis - ensuring robust operation in under-hood automotive environments.