Texas Instruments LMR33630ARNXR

Overview

LMR33630ARNXR from Texas Instruments is a synchronous step-down DC/DC converter optimized for rugged industrial power conversion. It operates from 3.8 V to 36 V input, delivers up to 3 A output current, supports adjustable output voltage from 1 V to 24 V, and features a 400 kHz fixed switching frequency in the 12-pin VQFN (3 mm × 2 mm) package with wettable flanks. It is used in motor drive inverters and PLC CPU power rails where wide VIN, high efficiency, and low EMI are critical.

For engineers reviewing the LMR33630ARNXR datasheet, LMR33630ARNXR pinout, LMR33630ARNXR application, or LMR33630ARNXR equivalent, key selection considerations include its 68 ns minimum on-time, integrated compensation, precision enable threshold (1.231 V typ), power-good flag with glitch filtering (60–170 µs), and thermal shutdown at 165°C - all validated for operation across –40°C to +125°C junction temperature.

Technical Context

The LMR33630ARNXR implements peak-current-mode control with automatic PFM/PWM mode transition to maintain high light-load efficiency (>95% peak). Its internal 5-V VCC LDO powers control circuitry, while the BOOT-SW bootstrap network drives the high-side MOSFET with R_DS(on) = 75 mΩ (HS) and 50 mΩ (LS) in the RNX package.

It integrates cycle-by-cycle current limiting, hiccup-mode short-circuit protection, thermal shutdown (165°C trip / 148°C recovery), input UVLO, and a precision enable comparator with 100 mV hysteresis. The VQFN package's symmetrical VIN/PGND layout and HotRod™ construction reduce parasitic inductance and EMI generation.

Key Specifications

Pinout & Package

The LMR33630ARNXR is housed in a 12-pin 3 mm × 2 mm VQFN package with wettable flanks and an exposed thermal pad (AGND). This package enables automated optical inspection (AOI) and improves thermal performance via PCB copper area conduction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33630ARNXR, the LMR33630BDDA offers higher frequency in a thermally robust HSOIC but sacrifices PCB area and EMI performance; the TPSM53603 eliminates magnetics and layout complexity at the expense of height and cost - making LMR33630ARNXR optimal for space-constrained, low-profile industrial converters requiring discrete component control.

Availability

LMR33630ARNXR is available at Aetrix Electronics and suitable for motor drive inverters, PLC CPU power supplies, drone flight controllers, and HVAC control units requiring stable component supply across extended temperature and long production lifecycles.

Supply support for LMR33630ARNXR 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 LMR33630ARNXR belongs to TI's SIMPLE SWITCHER® family - engineered specifically for rugged, wide-input-voltage DC/DC conversion in factory automation, motor control, and building systems where reliability under voltage transients and thermal stress is non-negotiable.

FAQ

What is the maximum output voltage supported by the LMR33630ARNXR?

The LMR33630ARNXR supports an adjustable output voltage range from 1 V to 24 V. This is achieved using an external resistor divider connected to the FB pin, referenced to the internal 1.0-V feedback voltage. The datasheet specifies that the maximum output voltage may extend to 95% of VIN under certain conditions; however, for guaranteed operation across –40°C to +125°C, 24 V is the validated upper limit when VIN ≥ 25.3 V. Always verify stability with the selected output voltage and load using TI's WEBENCH® Power Designer.

Does the LMR33630ARNXR require external compensation components?

No, the LMR33630ARNXR does not require external compensation components. It integrates a complete Type-II compensation network internally, eliminating the need for external capacitors or resistors in the feedback loop. This simplifies design, reduces bill-of-materials count, and improves immunity to layout variations. The internal compensation is optimized for typical 2.2-µH inductors and ceramic output capacitors, supporting stable operation across the full 1-V to 24-V output range and 0–3-A load.

What is the purpose of the NC pin on the LMR33630ARNXR VQFN package?

The NC pin (Pin 3) on the LMR33630ARNXR VQFN package has no internal connection to the die. Per TI's layout guidance, the SW pin (Pin 12) must be routed to this NC pad on the PCB to simplify the physical connection between the BOOT capacitor and the SW node. This routing technique reduces trace inductance and improves bootstrap capacitor effectiveness, especially critical for maintaining high-side FET gate drive integrity at high switching frequencies and heavy loads.

Can the LMR33630ARNXR operate with an input voltage below 3.8 V?

No, the LMR33630ARNXR is not specified or guaranteed to operate with input voltages below 3.8 V. Its absolute minimum recommended input voltage is 3.8 V, and attempting to operate below this risks failure to regulate, erratic enable behavior, or undefined power-good flag states. While the device may appear functional at slightly lower inputs in lab conditions, TI does not characterize or warrant performance below 3.8 V - particularly under temperature extremes or load transients. For sub-3.8-V applications, consider the LMR36015 or other dedicated low-VIN buck regulators.

How does the power-good (PG) flag behave during startup and fault conditions?

The LMR33630ARNXR power-good (PG) flag is an open-drain output that remains low for ~4 ms after EN is asserted, then transitions high when VOUT reaches 95% of target and remains within regulation windows (±3% to ±5%, depending on threshold). It pulls low during startup, thermal shutdown, current-limit hiccup, or if EN is deasserted. A built-in 60–170 µs glitch filter rejects brief output excursions caused by load steps or line transients. PG remains valid down to VIN = 2 V even when EN = 0 V, enabling brownout-safe system reset sequencing.