Texas Instruments LMR33630CRNXT

Overview

LMR33630CRNXT from Texas Instruments is a synchronous step-down DC/DC converter optimized for rugged industrial power conversion, delivering up to 3 A output current across an input range of 3.8 V to 36 V, with adjustable output voltage from 1 V to 24 V, peak efficiency >95%, and fixed 2.1 MHz switching frequency in the 3 mm × 2 mm VQFN package. It serves as a primary voltage regulator in motor drive inverters and PLC CPU power rails.

For engineers reviewing the LMR33630CRNXT datasheet, LMR33630CRNXT pinout, LMR33630CRNXT application, or LMR33630CRNXT equivalent, key selection criteria include its 2.1 MHz operation enabling compact magnetics, integrated compensation, precision enable with hysteresis, power-good flag with glitch filtering, and thermal shutdown with hiccup-mode short-circuit protection.

Technical Context

The LMR33630CRNXT implements peak-current-mode control with automatic PFM/PWM mode transition to maintain high light-load efficiency. Its architecture supports ultra-low minimum on-time (68 ns) and dropout operation down to VIN – VOUT = 150 mV at 1 A, enabling regulation from 3.8 V input to 3.3 V output.

It integrates dual MOSFETs (75 mΩ HS / 50 mΩ LS), internal 5-V VCC LDO, bootstrap gate driver, and analog ground (AGND) separate from power ground (PGND). The VQFN package features wettable flanks and symmetrical VIN/PGND layout to minimize EMI via magnetic field cancellation.

Key Specifications

Pinout & Package

The LMR33630CRNXT is housed in a 12-pin, 3.00 mm × 2.00 mm × 0.85 mm VQFN package with wettable flanks and exposed thermal pad (AGND). This next-generation HotRod™-derived layout minimizes parasitic inductance and EMI generation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33630BRNX, the LMR33630CRNXT delivers higher switching frequency for smaller passive components but requires tighter layout attention; compared with TPSM53603, it offers greater design flexibility and lower unit cost at the expense of engineering effort for magnetics selection and EMI tuning.

Availability

LMR33630CRNXT is available at Aetrix Electronics and suitable for motor drive inverters, PLC CPU power supplies, drone flight controllers, and HVAC control boards requiring stable component supply, long-term industrial lifecycle support, and AEC-Q100-qualified variants.

Supply support for LMR33630CRNXT 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 experience in industrial-grade power solutions.

The LMR33630 belongs to TI's SIMPLE SWITCHER® family-designed specifically for ease-of-use, ruggedness, and high efficiency in harsh industrial environments where reliability, wide input range, and minimal external components are critical.

FAQ

What is the switching frequency of the LMR33630CRNXT?

The LMR33630CRNXT operates at a fixed 2.1 MHz switching frequency, as confirmed in the device comparison table and electrical characteristics section of the official datasheet. This frequency is factory-trimmed and not user-adjustable. It enables compact filter design with typical 1–2.2 µH inductors and low-ESR ceramic capacitors, making the LMR33630CRNXT ideal for space-constrained industrial applications where high-frequency operation reduces solution size without sacrificing efficiency.

Does the LMR33630CRNXT support adjustable output voltage?

Yes, the LMR33630CRNXT supports fully adjustable output voltage from 1 V to 24 V using an external resistor divider connected to the FB pin. Its internal 1.0 V ±1.5% reference voltage sets regulation accuracy, and the datasheet provides detailed guidance on selecting RFBT and RFBB values. This configurability allows a single LMR33630CRNXT to serve multiple voltage rails-such as 3.3 V for MCUs and 5 V for peripherals-without requiring different part numbers.

What package type does the LMR33630CRNXT use?

The LMR33630CRNXT uses a 12-pin VQFN package measuring 3.00 mm × 2.00 mm × 0.85 mm with wettable flanks (orderable suffix RNX). This next-generation HotRod™-inspired package features symmetrical VIN/PGND pin placement to reduce EMI, low parasitic inductance, and enhanced thermal performance via the exposed thermal pad (AGND). It is distinct from the HSOIC-8 variant and requires specific land pattern and stencil design per TI's SLOA222 application note.

How does the power-good (PG) function work on the LMR33630CRNXT?

The LMR33630CRNXT's open-drain PG pin asserts high when the output voltage reaches and remains within ±5% of the target (e.g., 95–107% of VREF for rising edge), with built-in 170 µs glitch filtering to ignore transient excursions. It pulls low during startup, undervoltage, overcurrent, or thermal faults. The PG signal can drive microcontroller reset inputs directly (with pull-up to VCC or VOUT) and remains valid down to VIN = 2 V even when EN is low-enabling robust system-level power sequencing and fault monitoring in industrial control applications.

Is the LMR33630CRNXT suitable for automotive applications?

The LMR33630CRNXT itself is not AEC-Q100 qualified; however, Texas Instruments offers a pin-compatible AEC-Q100 Grade 1 qualified version under a separate orderable part number (LMR33630QRNXT). That variant shares identical electrical specifications, package, and pinout but undergoes additional automotive qualification testing. For non-safety-critical automotive ancillary systems (e.g., infotainment power rails), the standard LMR33630CRNXT may be used-but formal automotive deployment requires the Q-grade variant and full qualification documentation.