Texas Instruments LMR36503R5URPER

Overview

LMR36503R5URPER from Texas Instruments is a 3-V to 65-V, 0.3-A synchronous buck converter in a 2-mm × 2-mm VQFN-HR (RPE) package with wettable flanks omitted, fixed 5-V output, ultra-low 4 µA no-load IQ at 24 VIN, and adjustable switching frequency (200 kHz–2.2 MHz via RT pin). It delivers >90% peak efficiency at 1 MHz and supports industrial applications requiring high transient immunity (70-V input tolerance) and –40°C to +150°C junction operation.

For engineers reviewing the LMR36503R5URPER datasheet, LMR36503R5URPER pinout, LMR36503R5URPER application, or LMR36503R5URPER equivalent, key selection considerations include its fixed 5-V output configuration (no feedback divider), absence of wettable flanks, RT-based frequency programming capability, precision EN/UVLO threshold (1.263 V), and PGOOD flag with built-in glitch filter and 1.956-ms activation delay.

Technical Context

The LMR36503R5URPER uses peak current mode control with internal compensation, enabling stable regulation with minimal external output capacitance. Its architecture supports automatic frequency foldback during input transients to maintain regulation when minimum on/off times are exceeded.

It integrates a precision enable comparator (1.263 V threshold, 0.35 V hysteresis), an open-drain PGOOD output with delayed release and 106–110% overvoltage detection, and dual MOSFETs with RDS(on) of 560–920 mΩ (HS) and 280–460 mΩ (LS), optimized for high efficiency across light-to-full load in industrial environments.

Key Specifications

Pinout & Package

Package: VQFN-HR (RPE), 9-pin, 2.00 mm × 2.00 mm, no wettable flanks - enables high-density PCB layouts and automated optical inspection (AOI) compatibility despite absence of wettable flanks.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR36503R5RPER, LMR36503R5URPER trades wettable flanks for lower cost while retaining identical regulation performance and thermal behavior; versus LMR36506R5URPER, it offers tighter current rating and lower conduction loss at 0.3-A loads, improving efficiency in space-constrained sensor nodes.

Availability

LMR36503R5URPER is available at Aetrix Electronics and suitable for factory automation sensors, building HVAC controllers, and garden power tools requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for LMR36503R5URPER 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 industrial-grade DC/DC converter expertise.

The LMR36503R5URPER belongs to TI's LMR36503 family of ultra-small, high-voltage synchronous buck converters designed specifically for rugged industrial power supplies where size, efficiency, and transient robustness are critical.

FAQ

What is the maximum input voltage the LMR36503R5URPER can withstand without damage?

The LMR36503R5URPER has an absolute maximum input voltage rating of 70 V, allowing it to survive IEC 61000-4-5 surge transients. Its operational input range is 3.0 V (falling threshold) to 65 V, making it suitable for industrial 24-V and 48-V systems with significant line variation. This rating is confirmed in Section 7.1 Absolute Maximum Ratings of the official datasheet.

Does the LMR36503R5URPER require external feedback resistors for its 5-V output?

No, the LMR36503R5URPER features a fixed 5-V output configuration using the VOUT/BIAS pin variant, eliminating the need for external feedback resistors. The device achieves ±1.5% initial accuracy over temperature and load, as specified in Section 7.8 System Characteristics. This simplifies design and improves reliability compared to adjustable-output buck converters.

How does the RT pin function on the LMR36503R5URPER, and what frequency range does it support?

The RT pin on the LMR36503R5URPER enables programmable switching frequency from 200 kHz to 2.2 MHz via an external resistor to ground. Connecting RT to GND sets 2.2 MHz; connecting to VCC sets 1 MHz. Equation 1 in Section 8.3.2 defines RT = 18286 / F_SW^1.021, where F_SW is in kHz. This flexibility supports EMI compliance and inductor size optimization.

What is the quiescent current of the LMR36503R5URPER at no load, and under what conditions is it measured?

The LMR36503R5URPER draws 4 µA quiescent current at no load when configured for 5-V output, measured at 24 V_IN (Section 7.5 Electrical Characteristics, parameter IQ_24p0_Fixed). This ultra-low value is achieved in PFM mode and enables multi-year operation in battery-powered industrial sensors - a key differentiator versus competing 65-V buck converters.

Is the LMR36503R5URPER pin-compatible with other devices in the LMR36503 family?

Yes, the LMR36503R5URPER shares the same 9-pin VQFN-HR (RPE) package and pinout with all LMR36503 variants, including LMR36503R5RPER (wettable flanks) and LMR36503RFRPER (adjustable output). This enables drop-in replacement for design reuse, though output configuration (fixed vs. adjustable) and wettable flank presence must be verified per application requirements.