Texas Instruments LMR23615DRRT

Overview

LMR23615 from Texas Instruments is a synchronous step-down DC-DC converter delivering 1.5-A continuous output current with 4-V to 36-V input range, 60-ns minimum on-time, and internal current-mode control loop compensation. It integrates high-side and low-side MOSFETs (R_DS(on) = 160 mΩ / 95 mΩ), supports PFM light-load operation, and targets industrial power conditioning in PLC CPU and HVAC control systems.

For engineers reviewing the LMR23615 datasheet, LMR23615 pinout, LMR23615 application, or LMR23615 equivalent, key selection considerations include VIN_UVLO threshold (3.7 V typ), adjustable switching frequency (200 kHz–2.2 MHz), hiccup-mode short-circuit protection, thermal shutdown at 170 °C, and WSON-12 wettable flanks package compatibility with compact PCB layouts.

Technical Context

The LMR23615 employs fixed-frequency peak-current-mode control with internal slope compensation and cycle-by-cycle current limiting. Its integrated high-side/low-side NMOS switches enable synchronous rectification, while the precision 1-V reference and FB pin support ±1% output voltage regulation across temperature.

It features dual UVLO detection (VIN and VCC), programmable soft-start (6 ms), and frequency foldback during dropout-reducing f_SW below 400 kHz when TOFF_MIN is reached-to maintain regulation down to V_IN ≈ V_OUT + 0.5 V at full load. The EN/SYNC pin serves both enable control and external clock synchronization (200 kHz–2.2 MHz).

Key Specifications

Pinout & Package

The LMR23615 is housed in a 3.00 mm × 3.00 mm, 12-pin WSON package with exposed thermal pad (PowerPAD™), optimized for thermal performance and automated optical inspection via wettable flanks.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR23625DRRT, the LMR23615DRRT offers lower cost and thermal margin for ≤1.5-A loads; versus TPS54332DDAR, it delivers superior light-load efficiency, smaller footprint, and integrated protection-making it optimal for space-constrained industrial edge nodes.

Availability

LMR23615DRRT is available at Aetrix Electronics and suitable for factory automation, building HVAC control, and asset tracking applications requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant packaging.

Supply support for LMR23615DRRT 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 company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies for industrial, automotive, and communications markets.

The LMR236xx SIMPLE SWITCHER® product line is designed for rugged, easy-to-deploy DC-DC conversion in harsh industrial environments-emphasizing wide input range, integrated protection, and minimal external components for rapid design completion.

FAQ

What is the minimum input voltage required for LMR23615DRRT to regulate 5 V output at full 1.5-A load?

The LMR23615DRRT maintains regulation at 5 V output with 1.5-A load down to approximately 5.5 V input under typical conditions, enabled by frequency foldback that reduces switching frequency below 400 kHz when minimum off-time is reached. This extends effective dropout performance beyond fixed-frequency limits, allowing reliable operation during brownouts in 12-V industrial systems.

Does LMR23615DRRT support synchronization to an external clock, and what are the valid frequency and amplitude ranges?

Yes, LMR23615DRRT supports external clock synchronization via the EN/SYNC pin. Valid SYNC frequency range is 200 kHz to 2.2 MHz, with AC-coupled positive pulses requiring ≥2.8 V peak-to-peak amplitude and ≥100 ns minimum ON/OFF time. A 1-nF coupling capacitor and 100-kΩ Thevenin impedance at the EN/SYNC node are recommended for robust locking.

How does the internal compensation of LMR23615DRRT affect output capacitor selection?

The internal compensation of LMR23615DRRT allows stable operation with standard ceramic output capacitors as low as 10 µF, eliminating the need for tantalum or polymer types with specific ESR. TI recommends X5R/X7R dielectrics rated ≥16 V; total C_OUT ≥ 47 µF is advised for optimal transient response and EMI suppression across full load range.

Can LMR23615DRRT safely start up when the output voltage is already present (prebiased)?

Yes, LMR23615DRRT includes controlled soft-start into prebiased outputs. During startup, the internal reference ramps from 0 V to 1 V over 6 ms while the error amplifier remains inactive until V_FB rises above 0.4 V-preventing reverse current flow from the output into the SW node and avoiding potential damage to upstream sources or downstream circuitry.

What thermal management practices are required for LMR23615DRRT in continuous 1.5-A operation?

For continuous 1.5-A operation, LMR23615DRRT requires the exposed thermal pad (PAD) to be soldered to a minimum 200 mm² internal or bottom-layer copper pour connected to 4+ thermal vias (0.3-mm diameter) to inner ground planes. With this layout, junction-to-board thermal resistance drops to 3.4 °C/W, enabling operation up to 125 °C ambient at full load without derating.