Texas Instruments LMR23625CFDDA

Overview

LMR23625CFDDA from Texas Instruments is a 36-V, 2.5-A synchronous step-down DC-DC converter in an 8-pin HSOIC package with PowerPAD™, featuring 4–36 V input range, 2.1-MHz fixed-frequency forced-PWM operation, 75 µA no-load quiescent current, and integrated high- and low-side MOSFETs. It delivers regulated power to industrial control logic, PLC CPU rails, and GSM module power supplies.

For engineers reviewing the LMR23625CFDDA datasheet, LMR23625CFDDA pinout, LMR23625CFDDA application, or LMR23625CFDDA equivalent, key selection considerations include its FPWM-only mode (no PFM), absence of PGOOD output, internal compensation for minimal external components, and thermal performance in factory automation and wide-VIN battery-backed systems.

Technical Context

The LMR23625CFDDA uses fixed-frequency peak-current-mode control with 2.1-MHz nominal switching, enabling stable regulation without external loop compensation. Its FPWM-only operation eliminates light-load frequency modulation, ensuring constant ripple and predictable EMI behavior across load conditions.

It integrates 185-mΩ high-side and 105-mΩ low-side MOSFETs in the HSOIC package, supports soft-start into prebiased loads, and includes precision enable with 1.55-V typical rising threshold and 0.4-V hysteresis for robust system power sequencing and undervoltage lockout control.

Key Specifications

Pinout & Package

Package: 8-pin HSOIC with PowerPAD™ (4.89 mm × 3.90 mm); thermal pad must be soldered to PCB ground plane for effective heat dissipation and electrical stability.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR23625CDDA, the LMR23625CFDDA trades light-load efficiency for deterministic EMI behavior; compared with LMR23630CFDDA, it offers lower cost and thermal margin for 2.5-A applications without overdesign.

Availability

LMR23625CFDDA is available at Aetrix Electronics and suitable for factory automation systems, GSM telemetry modules, and HVAC control boards requiring stable component supply across long production lifecycles.

Supply support for LMR23625CFDDA 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 broad industrial and automotive focus.

The LMR23625CFDDA belongs to TI's SIMPLE SWITCHER® family of easy-to-use DC-DC regulators, designed specifically for rugged industrial power conditioning where reliability, wide input range, and minimal external components are critical.

FAQ

What distinguishes LMR23625CFDDA from other variants in the LMR23625 family?

The LMR23625CFDDA is the FPWM-only variant in HSOIC packaging - it lacks PFM capability and PGOOD output found in WSON versions. Unlike LMR23625CDDA, it guarantees fixed 2.1-MHz operation under all loads, making it ideal for EMI-sensitive environments. Its enable threshold and thermal shutdown parameters match the family baseline, ensuring consistent system integration.

Does LMR23625CFDDA support external frequency synchronization?

Yes, the LMR23625CFDDA supports external clock synchronization via its EN/SYNC pin, accepting AC-coupled signals from 200 kHz to 2.2 MHz. This allows precise timing alignment with system clocks or other switching regulators to avoid beat frequencies. The device maintains FPWM operation during sync, preserving constant ripple and regulation performance regardless of external clock jitter or duty cycle.

Can LMR23625CFDDA operate with a 3.3-V output from a 36-V input?

Yes, the LMR23625CFDDA can regulate 3.3 V from 36 V input using its 60-ns minimum on-time and peak-current-mode control. At this 9.2% duty cycle, the device remains in continuous conduction mode with stable regulation. TI recommends using a 2.2-µH inductor and low-ESR output capacitors; efficiency drops to ~72% at full load, verified in Figure 6-4 of the datasheet.

Is thermal pad connection required for LMR23625CFDDA reliability?

Yes, the thermal pad (Pin 9) of the LMR23625CFDDA must be soldered to a dedicated PCB copper pour tied to PGND. With RθJC(bot) = 3.6°C/W, this pad accounts for >85% of heat dissipation. Omitting it raises junction temperature by >40°C at 2.5-A load, risking thermal shutdown or accelerated aging. TI specifies minimum 4×4 mm exposed pad area with ≥4 thermal vias to inner ground planes.

What is the recommended feedback resistor configuration for LMR23625CFDDA?

For a 3.3-V output, use RFBB = 10 kΩ and RFBT = 23 kΩ (1% tolerance, ≤100 ppm/°C) to set FB voltage to 1.0 V. TI recommends RFBT between 10 kΩ and 100 kΩ to balance noise immunity and light-load efficiency. Avoid RFBT >1 MΩ due to increased susceptibility to leakage and noise; place resistors close to FB and AGND pins with guard ring grounded to AGND.