Texas Instruments LMR23630AFDDA

Overview

LMR23630AFDDA from Texas Instruments is a 36-V, 3-A synchronous step-down DC-DC converter in an 8-pin HSOIC package with PowerPAD™. It delivers regulated output from 4 V to 36 V input, supports PFM and forced PWM (FPWM) modes, features internal compensation, 400-kHz fixed switching frequency, and 75-µA quiescent current-ideal for industrial PLC CPU power rails.

For engineers reviewing the LMR23630AFDDA datasheet, LMR23630AFDDA pinout, LMR23630AFDDA application, or LMR23630AFDDA equivalent, key selection considerations include its FPWM mode for low-output-ripple operation, precision enable input for system power sequencing, integrated high- and low-side MOSFETs (185 mΩ/105 mΩ), thermal protection, and hiccup-mode short-circuit protection.

Technical Context

The LMR23630AFDDA uses peak-current-mode control with a fixed 400-kHz oscillator and no external RT pin-enabling immediate deployment without frequency-setting resistors. Its internal loop compensation eliminates external Type-II/III networks, while the FPWM option ensures constant-frequency operation across all load conditions.

It integrates both high-side and low-side NMOS switches, supports soft-start into prebiased loads, and implements precision enable logic with 1.55-V typical rising threshold and 0.4-V hysteresis-allowing robust system-level power sequencing and undervoltage lockout at 3.7-V VIN rising threshold.

Key Specifications

Pinout & Package

LMR23630AFDDA is housed in an 8-pin HSOIC (4.89 mm × 3.90 mm) with exposed PowerPAD™ thermal pad for enhanced heat dissipation. The package is RoHS-compliant and optimized for industrial PCB layouts requiring high thermal reliability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with LMR23630ADDA, the LMR23630AFDDA adds FPWM for consistent ripple performance; compared with LMR23630FDRR, it trades frequency adjustability and WSON packaging for simplified 400-kHz implementation in HSOIC-reducing design iteration time and component count.

Availability

LMR23630AFDDA is available at Aetrix Electronics and suitable for factory automation, building management systems, and industrial IoT edge nodes requiring stable component supply, long-term manufacturability, and automotive-grade reliability screening.

Supply support for LMR23630AFDDA 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 power solutions.

The LMR23630AFDDA belongs to TI's SIMPLE SWITCHER® family-designed specifically for ease-of-use in industrial, factory automation, and building control applications where wide input range, thermal robustness, and minimal external components are essential.

FAQ

What is the switching frequency configuration of the LMR23630AFDDA?

The LMR23630AFDDA operates at a fixed 400-kHz switching frequency with no external frequency-setting resistor required. Unlike adjustable versions (e.g., LMR23630FDRR), it lacks an RT pin-making it ideal for designs prioritizing simplicity and repeatable EMI behavior. This fixed frequency is factory-trimmed and remains stable across temperature and load, enabling straightforward filter design and predictable thermal performance in the 8-pin HSOIC package.

Does the LMR23630AFDDA support synchronization to an external clock?

Yes, the LMR23630AFDDA supports external clock synchronization via its EN/SYNC pin. When configured as SYNC input (with appropriate AC coupling capacitor), it accepts external clock signals from 200 kHz to 2200 kHz-allowing alignment with system clocks or other converters to reduce beat frequencies. This capability is retained despite the fixed 400-kHz internal oscillator, providing flexibility in multi-rail power systems without requiring frequency-adjustable variants.

What protection features does the LMR23630AFDDA include?

The LMR23630AFDDA integrates cycle-by-cycle current limiting, hiccup-mode short-circuit protection, thermal shutdown at 170 °C, VIN undervoltage lockout (3.7-V rising threshold), and VCC undervoltage lockout (3.2-V rising threshold). These protections operate autonomously without external components-ensuring safe recovery from overloads, wiring faults, or thermal stress in unattended industrial deployments. The hiccup mode disables switching for 5 ms (HSOIC) after six consecutive current-limit events, preventing thermal runaway.

Can the LMR23630AFDDA start up into a prebiased output?

Yes, the LMR23630AFDDA supports soft-start into a prebiased output-a critical feature for hot-swap and redundant power applications. Its internal soft-start circuitry monitors the FB pin voltage during startup and delays ramp-up until the output reaches a safe level, preventing reverse current flow through the low-side FET. This avoids potential damage to downstream capacitors or ICs and ensures glitch-free power-up in systems with backup supplies or shared output buses.

What is the recommended output voltage feedback divider for the LMR23630AFDDA?

The LMR23630AFDDA uses an internal 1-V reference, so the output voltage is set by a resistor divider from VOUT to FB. For optimal accuracy and noise immunity, TI recommends 1% tolerance, low-TCR resistors with RFBT between 10 kΩ and 100 kΩ. For example, a 5-V output uses RFBT = 40.2 kΩ and RFBB = 10.0 kΩ. Avoid RFBT > 1 MΩ to prevent noise susceptibility, and ensure the FB trace is short, guarded, and routed away from noisy nodes like SW or VIN.