Texas Instruments LMR38015FDRRR

Overview

LMR38015FDRRR from Texas Instruments is a synchronous buck DC/DC converter designed for wide-input industrial power rails, delivering 1.5A continuous output current across 4.2V–80V input, featuring forced PWM (FPWM) mode, 40µA quiescent current, and adjustable 200kHz–2.2MHz switching frequency in a 3mm × 3mm WSON-12 package. It supports prebiased start-up and integrates synchronous rectification, thermal shutdown, cycle-by-cycle current limiting, and precision enable for rugged MHEV/EV and factory automation systems.

For engineers reviewing the LMR38015FDRRR datasheet, LMR38015FDRRR pinout, LMR38015FDRRR application, or LMR38015FDRRR equivalent, key selection considerations include FPWM operation for low-output-ripple regulation, RT/SYNC pin programmability for EMI-sensitive designs, ±1.5% reference voltage tolerance over temperature, and compatibility with high-voltage input surges up to 85V absolute maximum.

Technical Context

The LMR38015FDRRR employs fixed-frequency peak-current mode control with internal compensation, enabling stable regulation using minimal external components. Its FPWM variant maintains constant switching frequency and tight output voltage regulation even at light loads-unlike PFM variants-while supporting synchronization to external clocks from 300kHz to 2.1MHz via the RT/SYNC pin.

It integrates high-side (303mΩ) and low-side (133mΩ) MOSFETs, features 97% maximum duty cycle with frequency foldback down to ~133kHz during dropout, and includes a precision open-drain power-good flag with built-in glitch filtering (45µs), UVLO-controlled enable with 1.1V–1.25V threshold, and thermal shutdown at 163°C with 13°C hysteresis.

Key Specifications

Pinout & Package

LMR38015FDRRR is housed in a 12-pin WSON (DRR) package with wettable flanks and integrated PowerPAD™ thermal pad (3.00mm × 3.00mm). The exposed thermal pad must be soldered to PCB ground for optimal thermal performance (R_θJB = 21.7°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR38015SDRRR and LMR36515DRRR, the LMR38015FDRRR uniquely combines FPWM operation, 150°C junction rating, and 85V absolute maximum input-making it the only option among the three qualified for MHEV auxiliary power units and industrial transport systems requiring both high-voltage resilience and deterministic switching behavior.

Availability

LMR38015FDRRR is available at Aetrix Electronics and suitable for industrial transport, wireless infrastructure, factory automation, and MHEV/EV auxiliary power applications requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.

Supply support for LMR38015FDRRR 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 expertise in high-reliability industrial and automotive power conversion.

The LMR38015FDRRR belongs to TI's SIMPLE SWITCHER® family of easy-to-use DC/DC converters, engineered specifically for rugged industrial and transportation applications demanding wide input range, high temperature operation, and minimal external component count.

FAQ

What distinguishes LMR38015FDRRR from other variants like LMR38015SDRRR?

The LMR38015FDRRR implements forced PWM (FPWM) mode, ensuring constant switching frequency and low output voltage ripple even at light loads-ideal for noise-sensitive applications such as RF power supplies or precision ADC references. In contrast, LMR38015SDRRR uses PFM mode for superior light-load efficiency but introduces variable frequency and higher ripple. Both share identical 4.2V–80V input, 1.5A output, and WSON-12 packaging, but only the FDRRR variant disables spread spectrum and enables deterministic timing behavior.

Can LMR38015FDRRR operate with a 48V input and deliver 5V/1.5A output reliably?

Yes, the LMR38015FDRRR is fully specified for 48V input operation and delivers 1.5A continuously at 5V output across –40°C to +150°C junction temperature. At 48V_IN/5V_OUT, typical efficiency exceeds 92% at 1A with 400kHz switching and standard external components. Its 97% maximum duty cycle and frequency foldback ensure regulation during input transients, while the 303mΩ/133mΩ integrated MOSFETs minimize conduction losses without requiring heatsinking in most PCB layouts.

How does the RT/SYNC pin function in LMR38015FDRRR, and what external components are needed?

In LMR38015FDRRR, the RT/SYNC pin configures switching frequency via an external resistor to GND (e.g., 64.9kΩ for 400kHz) or accepts an external clock signal (300kHz–2.1MHz) for synchronization. No external components are required for basic resistor-based configuration-only the RT resistor and a 100nF ceramic capacitor from BOOT to SW. When synchronizing, a 1pF coupling capacitor and 50Ω termination resistor are recommended to isolate the clock source and maintain default frequency during clock absence.

Does LMR38015FDRRR support prebiased output start-up, and how is it enabled?

Yes, LMR38015FDRRR supports prebiased output start-up-allowing the output capacitor to retain voltage during input power cycling without damaging the IC or causing reverse current flow. This feature is enabled automatically when the EN pin is asserted while V_OUT is already present; no external circuitry or configuration is required. It is especially valuable in redundant power systems and hot-swap applications where output voltage must remain stable during input interruptions.

What thermal performance can be expected from LMR38015FDRRR in a standard 2-layer PCB layout?

With the thermal pad of the LMR38015FDRRR soldered to a 250mm² internal or bottom-layer copper pour (2oz Cu), typical thermal resistance is R_θJA ≈ 42°C/W-enabling 1.5A continuous operation at 85°C ambient without forced airflow. In a 4-layer board with dedicated ground/power planes and thermal vias under the EP pad, R_θJA improves to ~28°C/W. The device's 150°C maximum junction temperature and 13°C thermal hysteresis provide margin for transient overloads and enclosure heating.