Texas Instruments LMR38010FDDAR

Overview

LMR38010FDDAR from Texas Instruments is a 4.2-V to 80-V, 1-A synchronous buck DC/DC converter with forced PWM (FPWM) mode, 40-µA quiescent current, ±1.0% reference voltage accuracy at 25°C, and integrated high-side/low-side MOSFETs in an 8-pin HSOIC PowerPAD package. It delivers regulated power in industrial transport and factory automation systems where input voltage dips down to 4.2 V must be tolerated.

For engineers reviewing the LMR38010FDDAR datasheet, LMR38010FDDAR pinout, LMR38010FDDAR application, or LMR38010FDDAR equivalent, key selection criteria include FPWM operation for low output ripple, 200-kHz–2.2-MHz adjustable switching frequency, precision enable with 1.1–1.4-V turn-on threshold, thermal shutdown at 163°C, and support for pre-biased start-up in MHEV/EV subsystems.

Technical Context

The LMR38010FDDAR uses fixed-frequency peak-current mode control with internal compensation, enabling stable regulation across wide input ranges without external loop components. Its FPWM mode ensures constant switching frequency and tight output voltage regulation even at light loads, unlike PFM variants.

It integrates 303-mΩ high-side and 133-mΩ low-side NMOS switches, supports frequency synchronization from 300 kHz to 2.1 MHz via RT/SYNC, and features a true open-drain power-good flag with 40-µs glitch filtering and 90–114% FB voltage thresholds for reliable system monitoring.

Key Specifications

Pinout & Package

LMR38010FDDAR is housed in an 8-pin HSOIC (DDA) package with exposed thermal pad (PowerPAD™), measuring 4.89 mm × 3.90 mm. The package supports high-power dissipation with R_θJA = 42.9°C/W and R_θJB = 13.6°C/W when mounted on a 2-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR38010SDDAR and LMR36510ADDA, the LMR38010FDDAR uniquely balances 80-V input resilience, FPWM stability, and industrial-grade thermal performance - making it optimal for harsh-environment applications demanding both wide VIN and predictable EMI behavior.

Availability

LMR38010FDDAR is available at Aetrix Electronics and suitable for industrial transport, wireless infrastructure, and factory automation applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing from authorized channels.

Supply support for LMR38010FDDAR 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 LMR38010FDDAR belongs to TI's SIMPLE SWITCHER® family - engineered for rugged, easy-to-deploy DC/DC conversion in wide-input industrial and transportation systems where reliability, low BOM count, and minimal design effort are critical.

FAQ

What is the primary difference between LMR38010FDDAR and LMR38010SDDAR?

The LMR38010FDDAR operates exclusively in forced PWM (FPWM) mode, ensuring constant switching frequency and minimal output voltage ripple across all load conditions. In contrast, the LMR38010SDDAR uses pulse-frequency modulation (PFM) at light loads to achieve lower quiescent current (still 40 µA), but sacrifices frequency stability and increases output ripple. This makes LMR38010FDDAR preferable for noise-sensitive applications like RF power supplies or precision analog circuits where predictable EMI is essential.

Does LMR38010FDDAR support synchronization to an external clock?

Yes, the LMR38010FDDAR supports external clock synchronization via the RT/SYNC pin, accepting square-wave inputs from 300 kHz to 2.1 MHz. When an external clock is applied above the PLL upper threshold (~2 V), the internal oscillator disables and locks to the incoming signal's falling edge. This feature enables deterministic EMI reduction in multi-rail systems and eliminates beat frequencies between switching regulators - a key advantage in dense PCB layouts found in wireless infrastructure equipment.

Can LMR38010FDDAR start up into a pre-biased output voltage?

Yes, the LMR38010FDDAR supports pre-biased start-up, allowing safe activation when the output rail already holds voltage - common in hot-swap, redundant power, or backup-supply scenarios. During pre-bias start-up, the device prevents reverse current flow through its integrated low-side MOSFET by disabling synchronous rectification until regulation is established. This protects downstream circuitry and avoids bus contention, a critical capability in MHEV battery management subsystems.

What thermal performance can be expected from LMR38010FDDAR in a standard 2-layer PCB layout?

In a typical 2-layer evaluation board layout, the LMR38010FDDAR achieves a junction-to-board thermal resistance (R_θJB) of 13.6°C/W and a junction-to-ambient resistance (R_θJA) of 42.9°C/W. With 1-A load at 24-V input and 5-V output, power dissipation is ~0.5 W; this results in approximately 21.5°C junction-to-ambient rise above ambient. Proper use of the exposed PowerPAD™ thermal pad - soldered to a ≥1 cm² copper pour connected to internal ground planes - is essential to realize these ratings and sustain full-load operation at 105°C ambient.

How does the power-good (PG) flag on LMR38010FDDAR behave during startup and fault conditions?

The LMR38010FDDAR's open-drain PG pin asserts high after a 4-ms internal soft-start delay once EN is enabled and output voltage reaches 90% of target (e.g., 4.5 V on a 5-V rail). It pulls low during undervoltage (FB < 90% VREF), overcurrent, thermal shutdown, or when EN is deasserted. A built-in 40-µs glitch filter rejects transient excursions, and the flag remains valid down to 2-V input - enabling reliable system reset signaling even during brownout conditions. No external supervisor IC is needed.