Texas Instruments LMR33620CRNXR

Overview

LMR33620CRNXR from Texas Instruments is a synchronous step-down DC/DC converter optimized for rugged industrial power conversion, delivering up to 2 A output current across an input range of 3.8 V to 36 V, with adjustable output voltage from 1 V to 24 V, fixed 2.1 MHz switching frequency, and peak efficiency exceeding 95% in VQFN package. It serves as the primary voltage regulator in motor drive inverters and PLC CPU power rails.

For engineers reviewing the LMR33620CRNXR datasheet, LMR33620CRNXR pinout, LMR33620CRNXR application, or LMR33620CRNXR equivalent, key selection considerations include its 2.1 MHz operation in the 3 mm × 2 mm VQFN package with wettable flanks, 68 ns minimum on-time, precision enable thresholds (1.231 V typical), and integrated power-good flag with glitch filtering.

Technical Context

The LMR33620CRNXR 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 while clamping minimum off-time at 52 ns (VQFN) and integrating internal compensation to eliminate external loop components.

It features dual current-limit protection-cycle-by-cycle peak limit (3.5 A typical) and valley limit (2.45 A typical)-plus hiccup-mode short-circuit response (94 ms burst interval), thermal shutdown at 165°C, and precision enable with 100 mV hysteresis to support programmable UVLO via external resistor divider.

Key Specifications

Pinout & Package

The LMR33620CRNXR is housed in a 12-pin 3 mm × 2 mm VQFN package with wettable flanks and exposed thermal pad (AGND). This RoHS-compliant, lead-free package supports automated optical inspection and improves thermal performance (R_θJB = 23.3°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR33620BRNX and TPS54202DRCT, the LMR33620CRNXR offers the highest fixed frequency (2.1 MHz) in the smallest footprint with built-in PG flag and functional safety documentation-making it optimal for space-constrained, safety-aware industrial power rails where EMI and startup reliability are prioritized.

Availability

LMR33620CRNXR is available at Aetrix Electronics and suitable for motor drive inverters, PLC CPU power supplies, HVAC control units, and elevator control systems requiring stable component supply across extended temperature and long product lifecycles.

Supply support for LMR33620CRNXR 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 ICs, with decades of industrial-grade reliability validation and broad automotive qualification coverage.

The LMR33620CRNXR belongs to TI's SIMPLE SWITCHER® family of easy-to-use DC/DC regulators, designed specifically for rugged industrial environments where wide input range, high efficiency, and robust protection are mandatory.

FAQ

What is the maximum output voltage supported by the LMR33620CRNXR?

The LMR33620CRNXR supports an adjustable output voltage range from 1 V to 24 V. The upper limit is constrained by the feedback reference voltage (1.0 V) and external resistor divider ratio. For outputs above 24 V, the device enters dropout mode; however, per datasheet Section 7.3, the maximum recommended output is 24 V to ensure regulation accuracy and thermal margin across the full operating temperature range.

Does the LMR33620CRNXR require external compensation components?

No, the LMR33620CRNXR integrates a complete Type-II compensation network internally. This eliminates the need for external capacitors or resistors in the feedback loop, simplifying design, reducing PCB area, and improving immunity to layout variations. The internal compensation is optimized for stability with standard 1–2.2 µH inductors and ceramic output capacitors.

How does the power-good (PG) flag behave during startup and fault conditions for the LMR33620CRNXR?

The LMR33620CRNXR PG pin remains low for approximately 4 ms after EN is asserted, then transitions high when VOUT reaches 95% of target. It pulls low again during undervoltage, overcurrent, thermal shutdown, or EN deactivation. A 170 µs internal glitch filter prevents false triggering from brief transients, and the open-drain output requires an external pull-up resistor (e.g., 100 kΩ to VOUT) to function correctly.

What thermal performance can be expected from the LMR33620CRNXR in a standard 4-layer PCB layout?

In a JEDEC-standard 4-layer board, the LMR33620CRNXR exhibits a junction-to-board thermal resistance (R_θJB) of 23.3°C/W. With proper thermal pad soldering to an internal ground plane, it sustains 2 A continuous output at ambient temperatures up to 85°C without derating. Thermal shutdown activates at 165°C junction temperature, with hysteresis enabling recovery at 148°C.

Can the LMR33620CRNXR operate in dropout mode, and what is its minimum dropout voltage?

Yes, the LMR33620CRNXR supports forced PWM and PFM dropout operation. At 1 A load and 5 V output, its measured dropout voltage (VIN – VOUT) is 150 mV. This is enabled by its 68 ns minimum on-time and adaptive frequency reduction, allowing regulation even when input falls within ~100 mV of the desired output voltage.