Texas Instruments LMR33620CRNXT

Overview

LMR33620CRNXT from Texas Instruments is a synchronous step-down DC/DC converter delivering 2 A output current across 3.8 V to 36 V input, with adjustable 1 V–24 V output, 2.1 MHz switching frequency, and peak efficiency >95% in the 3 mm × 2 mm VQFN package. It serves as a rugged industrial power supply core in motor drives, PLCs, and HVAC controllers.

For engineers reviewing the LMR33620CRNXT datasheet, LMR33620CRNXT pinout, LMR33620CRNXT application, or LMR33620CRNXT equivalent, key selection criteria include its 2.1 MHz fixed-frequency operation, 68 ns minimum on-time, integrated compensation, precision enable threshold (1.231 V typ), and power-good flag with glitch filtering - all validated for –40°C to +125°C junction operation.

Technical Context

The LMR33620CRNXT implements peak-current-mode control with automatic PFM/PWM mode transition to maintain high light-load efficiency. Its architecture supports dropout operation down to VIN – VOUT = 150 mV at 1 A and integrates internal 5-V VCC LDO, bootstrap circuitry, and zero-current detection for diode emulation.

Protection includes cycle-by-cycle current limit (ISC = 3.5 A typ), hiccup-mode short-circuit response (94 ms burst interval), thermal shutdown (165°C), and input UVLO. The VQFN package features wettable flanks and symmetrical VIN/PGND layout to minimize EMI via magnetic field cancellation.

Key Specifications

Pinout & Package

The LMR33620CRNXT is housed in a 12-pin VQFN package (3.0 mm × 2.0 mm × 0.85 mm) with wettable flanks and an exposed thermal pad (AGND). This package enables low-inductance layout, enhanced thermal dissipation, and automated optical solder-joint inspection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33620BRNX and TPS54202HDDCR, the LMR33620CRNXT delivers highest power density at 2.1 MHz with fully integrated functionality - eliminating compensation parts, providing PG status, and enabling precise enable-controlled sequencing without added circuitry.

Availability

LMR33620CRNXT is available at Aetrix Electronics and suitable for motor drive systems, factory automation PLCs, HVAC control units, and elevator control systems requiring stable component supply, long-term lifecycle assurance, and automotive-grade reliability validation.

Supply support for LMR33620CRNXT 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 expertise in high-reliability industrial and automotive power solutions.

The LMR33620CRNXT belongs to TI's SIMPLE SWITCHER® family - engineered specifically for rugged industrial DC/DC conversion where wide input range, small solution size, and robust protection are mandatory.

FAQ

What is the switching frequency of the LMR33620CRNXT and how is it set?

The LMR33620CRNXT operates at a fixed 2.1 MHz switching frequency, determined by internal oscillator circuitry and not user-adjustable. This frequency is factory-trimmed and specified across –40°C to +125°C junction temperature. Unlike programmable variants, the 'C' suffix in LMR33620CRNXT denotes this specific 2.1 MHz version in the VQFN package, enabling consistent timing behavior and predictable EMI profile in high-density layouts.

Does the LMR33620CRNXT require external compensation components?

No, the LMR33620CRNXT includes a fully integrated compensation network optimized for stability with standard output capacitor types (e.g., 22–47 µF ceramic). This eliminates external RC networks required by many competing regulators, reducing bill-of-materials count, PCB area, and design iteration time. The internal compensation is validated across the full 1 V–24 V output range and supports typical inductor values from 1.5 µH to 4.7 µH.

How does the power-good (PG) function work on the LMR33620CRNXT?

The LMR33620CRNXT PG pin is an open-drain output that goes high (after ~4 ms soft-start delay) when the FB voltage reaches 105% of the 1.0 V reference and remains within ±5% regulation. It pulls low during faults (overload, thermal shutdown, UVLO) or when EN is deasserted. A built-in 170 µs glitch filter prevents false triggering from transient line/load disturbances. External pull-up to VCC or VOUT (via 100 kΩ) is required; floating PG is acceptable if unused.

What thermal performance can be expected from the LMR33620CRNXT in a typical 4-layer PCB layout?

In a standard JEDEC 4-layer board with 2 oz copper and 1-in² thermal pad area, the LMR33620CRNXT achieves a junction-to-board thermal resistance (RθJB) of 23.3°C/W. At 2 A output with 12 V input and 5 V output, typical power dissipation is ~0.35 W, resulting in ~8.2°C rise above board temperature. Full derating begins above 125°C junction, with thermal shutdown activating at 165°C to protect the device.

Is the LMR33620CRNXT suitable for functional safety–compliant designs?

Yes - the LMR33620CRNXT is functional safety-capable, with documentation available to support ISO 26262 ASIL-B or IEC 61508 SIL-2 system-level development. Key enablers include precision enable thresholds (±10 mV), glitch-filtered power-good flag, hiccup-mode short-circuit protection with defined fault timing (94 ms), and comprehensive failure mode analysis in TI's safety manual for LMR33620. It is not AEC-Q100 qualified, but the LMR33620Q variant is.