Texas Instruments LMR38025FDRRR

Overview

LMR38025FDRRR from Texas Instruments is a synchronous buck DC/DC converter designed for wide-input industrial power rails, delivering 2.5A continuous output current with 40µA quiescent current, 4.2V–80V input range, and forced PWM (FPWM) operation to ensure low output ripple and constant switching frequency across all load conditions. It integrates high- and low-side MOSFETs, internal compensation, and precision enable in a thermally enhanced 12-pin WSON package.

For engineers reviewing the LMR38025FDRRR datasheet, LMR38025FDRRR pinout, LMR38025FDRRR application, or LMR38025FDRRR equivalent, key selection considerations include FPWM mode requirement, absence of spread spectrum, thermal performance in 3mm × 3mm wettable flank packaging, and compatibility with prebiased start-up and external frequency synchronization.

Technical Context

The LMR38025FDRRR employs fixed-frequency peak-current mode control with internal voltage loop compensation, enabling stable regulation using minimal external components. Its FPWM variant maintains constant 200kHz–2.2MHz switching across light-to-full load, eliminating PFM-induced frequency variation and output voltage dither.

It features a high-voltage enable pin supporting direct VIN connection or precision UVLO sequencing, integrated open-drain power-good flag with built-in glitch filtering (45µs), and RT/SYNC pin configurable either as resistor-set oscillator or 300kHz–2.1MHz external clock input - with automatic mode reversion if sync signal fails.

Key Specifications

Pinout & Package

LMR38025FDRRR is housed in a 3.00mm × 3.00mm, 12-pin WSON package with wettable flanks and exposed thermal pad (PowerPAD™), optimized for automated optical inspection (AOI) and thermal performance on standard PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR38025SDRRR and LM61480RQR, the LMR38025FDRRR uniquely balances FPWM stability, 80V ruggedness, and prebiased start-up - making it the sole choice for industrial 24V/48V systems requiring deterministic low-ripple power with brownout resilience.

Availability

LMR38025FDRRR is available at Aetrix Electronics and suitable for industrial transport, factory automation, and wireless infrastructure applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing from authorized channels.

Supply support for LMR38025FDRRR 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 conversion.

The LMR38025FDRRR belongs to TI's SIMPLE SWITCHER® family - engineered specifically for rugged, wide-input industrial power supplies where simplicity, thermal robustness, and functional safety readiness are mandatory design criteria.

FAQ

What distinguishes LMR38025FDRRR from other variants in the LMR38025 family?

The LMR38025FDRRR is the forced PWM (FPWM) version of the LMR38025 family, meaning it maintains constant switching frequency and low output voltage ripple across all load conditions - unlike the PFM variant (LMR38025SDRRR). It does not include spread spectrum EMI reduction. This makes LMR38025FDRRR ideal for timing-sensitive applications such as FPGA core supplies or RF bias rails where frequency dither or ripple-induced jitter is unacceptable.

Does LMR38025FDRRR support start-up into a precharged output capacitor?

Yes, LMR38025FDRRR supports prebiased output start-up, allowing safe activation when the output voltage is already present (e.g., due to hold-up capacitance or back-powering). During this event, the device prevents reverse current flow through the internal low-side MOSFET and avoids output overshoot - a critical capability for hot-swap and redundant power systems where LMR38025FDRRR is commonly deployed.

What is the minimum recommended input voltage for reliable operation of LMR38025FDRRR?

The LMR38025FDRRR has a specified minimum operating input voltage of 4.2V after start-up, and can sustain regulation down to this level using up to 97% duty cycle. Its absolute minimum start-up voltage is also 4.2V, and it supports near-100% duty cycle operation to minimize dropout - making LMR38025FDRRR especially suitable for brownout-prone industrial 24V systems where input may dip below 12V during motor startup or fault conditions.

Can LMR38025FDRRR be synchronized to an external clock, and what are the valid frequency ranges?

Yes, LMR38025FDRRR supports external clock synchronization via its RT/SYNC pin. When driven with a clean square wave, it locks to input frequencies from 300kHz to 2.1MHz using falling-edge detection. The internal PLL reverts automatically to resistor-programmed mode if the external clock stops - ensuring fail-safe operation. This capability allows LMR38025FDRRR to align switching edges with system clocks or avoid sensitive EMI bands in complex multi-rail power architectures.

What thermal performance can be expected from LMR38025FDRRR on a standard 2-layer PCB?

On a standard 2-layer PCB with 1oz copper and no dedicated thermal vias, LMR38025FDRRR exhibits a junction-to-ambient thermal resistance (RθJA) of 54.3°C/W. With proper layout - including a solid PGND plane connected to the exposed thermal pad via ≥6 thermal vias - power dissipation up to ~1.8W (at 2.5A, 24V→5V) keeps junction temperature within safe limits at 85°C ambient. For higher reliability, TI recommends verifying temperature rise using the measured RθJB (21.7°C/W) and board-level thermal modeling.