Texas Instruments LMR36500P3RPER

Overview

LMR36500P3RPER from Texas Instruments is a 3-V to 65-V, 50-mA synchronous buck DC/DC converter in a 2-mm × 2-mm HotRod™ VQFN-HR package, featuring peak current mode control, internal compensation, and precision EN/UVLO for rugged industrial power rails. It delivers fixed 3.3-V output with ±1.5% accuracy in FPWM mode, supports input transients up to 70 V, and achieves >80% peak efficiency at 1 MHz.

For engineers reviewing the LMR36500P3RPER datasheet, LMR36500P3RPER pinout, LMR36500P3RPER application, or LMR36500P3RPER equivalent, key selection considerations include its ultra-compact footprint, light-load PFM operation, RT-pin programmable frequency (200 kHz–2.2 MHz), integrated PGOOD with glitch filter, and –40°C to +150°C junction temperature range for harsh environments.

Technical Context

The LMR36500P3RPER uses peak current mode control with internal compensation, enabling stable regulation with minimal external output capacitance. Its precision EN/UVLO threshold (1.16–1.36 V) and hysteresis (0.285–0.425 V) allow accurate start-up sequencing and external undervoltage lockout implementation without additional circuitry.

Switching frequency is set via an external resistor from the RT pin to GND, supporting 200 kHz–2.2 MHz operation; the device automatically reduces frequency during dropout to maintain regulation. The open-drain PGOOD pin includes built-in 15–40 µs glitch filtering and 1.7–2.16 ms activation delay, eliminating need for external voltage supervisors in most applications.

Key Specifications

Pinout & Package

VQFN-HR (RPE) package: 9-pin, 2.0 mm × 2.0 mm body with wettable flank leads and corner anchor pads for enhanced solder joint reliability and automated optical inspection (AOI) compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LMR36500P3RPER, LMR36503P3RPER offers higher current headroom in the same footprint, while TPS63020DSJR enables operation from sub-3-V sources at the cost of added complexity and reduced efficiency above 5 V input - making LMR36500P3RPER optimal for fixed 3.3-V industrial rails with wide-input resilience.

Availability

LMR36500P3RPER is available at Aetrix Electronics and suitable for factory automation sensors, building HVAC controllers, and portable power tools requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceability.

Supply support for LMR36500P3RPER 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 delivering analog, embedded processing, and connectivity technologies with over 90 years of innovation in power management ICs.

The LMR36500P3RPER belongs to TI's LMR365xx family of wide-input, low-I_Q buck converters designed specifically for space-constrained, high-reliability industrial power rails - emphasizing small size, light-load efficiency, and ruggedness over 3–65 V input ranges.

FAQ

What is the minimum input voltage required for LMR36500P3RPER to start regulation?

The LMR36500P3RPER has a rising UVLO threshold of 3.4–3.55 V and a falling threshold of 2.45–2.7 V. Regulation begins once VIN exceeds the rising threshold; below that, the device remains in shutdown with ~0.5 µA quiescent current. This ensures reliable startup across wide-input industrial supplies while avoiding brownout oscillation.

Does LMR36500P3RPER require external feedback resistors for its fixed 3.3-V output?

No. The LMR36500P3RPER is a fixed-output variant: the VOUT/FB pin is internally configured for 3.3 V, so no external feedback resistors are needed. This simplifies layout, reduces BOM count, and improves accuracy versus adjustable versions - output voltage is specified at ±1.5% in FPWM mode across temperature and load.

Can LMR36500P3RPER operate with input voltages above 65 V?

The absolute maximum rating for VIN is 70 V, and the device is characterized to handle transients up to that level. However, continuous operation above 65 V violates the recommended operating conditions and may impact reliability, lifetime, or parametric performance. For sustained >65 V operation, derating or alternate solutions should be evaluated.

How does the PGOOD pin of LMR36500P3RPER behave during startup and fault conditions?

The PGOOD pin of LMR36500P3RPER remains low until output reaches 93–96.5% of target (falling threshold), then asserts high after a 1.7–2.16 ms delay. It goes low during EN deactivation, thermal shutdown, current limit, or output undervoltage/overvoltage. A built-in 15–40 µs glitch filter prevents false triggering during transient excursions.

What is the purpose of the RT pin on LMR36500P3RPER, and how is it used?

The RT pin on LMR36500P3RPER sets switching frequency from 200 kHz to 2.2 MHz via an external resistor to GND. Using Equation 1 (RT = 18286 / Fsw^1.021), designers select resistor values - e.g., 39.2 kΩ yields ~400 kHz. This enables EMI optimization, inductor size reduction, and avoidance of sensitive frequency bands without changing the IC or layout.