Infineon Technologies IR3721MTRPBF

Overview

IR3721MTRPBF from Infineon Technologies (formerly International Rectifier) is a TruePower™ analog-output power monitor IC for DC-DC buck and multiphase converters. It measures inductor current via DCR or shunt sensing, delivers duty-ratio-modulated DI output, supports thermal compensation via VRT pin, and achieves ±2.5% static accuracy over 0.5–1.8 V VO range with 435–589 kHz sampling frequency.

For engineers reviewing the IR3721MTRPBF datasheet, IR3721MTRPBF pinout, IR3721MTRPBF application, or IR3721MTRPBF equivalent, key selection criteria include DCR-based current sensing accuracy, VK-modulated analog power output generation, thermal compensation network design using RT, and compatibility with 3.3 V bias and 10-pin 3×3 mm DFN packaging.

Technical Context

The IR3721 implements a patented TruePower™ architecture that multiplies sensed inductor current (via VCS–VO differential input) with output voltage (via VK connection to VO) to generate a duty-ratio-modulated DI signal whose filtered output is proportional to real-time power. Its internal ΔΣ converter operates at 435–589 kHz with ±0.5 mV comparator offset and supports Kelvin-connected VO for precision DCR sensing.

Thermal compensation is implemented through the VRT pin, where an external RT network-comprising fixed resistors and optionally an NTC thermistor-counteracts copper inductor DCR drift. The device accepts 5–150 mV full-scale current sense ranges and maintains 2.5% duty ratio accuracy under specified conditions (VO = 1 V, VDCR = 20 mV, RCS1+RCS2 = 600 Ω, TJ = 65°C).

Key Specifications

Pinout & Package

IR3721MTRPBF is housed in a RoHS-compliant, lead-free 10-pin DFN package (3 mm × 3 mm body, 0.5 mm pitch) with exposed thermal pad connected to GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power monitor applications.

Compared with ISL68127 and MAX34451, IR3721MTRPBF uniquely delivers a self-contained, analog TruePower™ output with thermal compensation support in a minimal 3×3 mm footprint-ideal for systems needing low-latency, low-overhead power telemetry without digital bus dependencies.

Availability

IR3721MTRPBF is available at Aetrix Electronics and suitable for microprocessor core power monitoring, GPU VRM telemetry, DDR memory rail power measurement, and ASIC/FPGA adaptive voltage scaling requiring stable component supply and long-term lifecycle continuity.

Supply support for IR3721MTRPBF 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

Infineon Technologies is a global semiconductor leader specializing in power management, sensor, and automotive ICs, with deep expertise in high-efficiency DC-DC conversion and power system monitoring.

The IR3721 belongs to Infineon's TruePower™ analog power monitor product line, designed specifically to enable accurate, low-overhead real-time power telemetry in high-density, thermally constrained computing and graphics power supplies.

FAQ

What is the function of the VK pin?

The VK pin serves as the voltage multiplier input for the TruePower™ engine. When connected to VO, the DI output's duty ratio and amplitude jointly produce an RC-filtered analog voltage proportional to instantaneous power (IL × VO). If tied to a fixed voltage, the output becomes proportional only to current. Its 0.5–1.8 V operating range aligns with standard buck output voltages.

How does thermal compensation work with the VRT pin?

The VRT pin sources a reference current used to scale the internal switched current source driving VCS. An external RT network-typically a series combination of fixed resistors and an NTC thermistor-is connected from VRT to GND. As temperature rises, the thermistor resistance drops, reducing RT and counteracting the positive temperature coefficient of copper inductor DCR, thereby stabilizing current measurement accuracy.

Can IR3721MTRPBF be used with shunt resistor sensing instead of DCR?

Yes. The IR3721 supports both DCR and shunt-based current sensing. For shunt use, VO is connected directly across the shunt, eliminating the need for thermal compensation components on VRT. The device's wide 5–150 mV full-scale current range and low comparator offset (±0.5 mV) make it suitable for precision shunt applications without additional gain stages.

What is the minimum recommended RC filter configuration for the DI output?

A first-order RC filter with R = 10 kΩ and C = 10 nF (τ = 100 μs) is recommended for most applications, yielding a −3 dB cutoff near 1.6 kHz-sufficient to reconstruct power waveforms below 200 kHz while rejecting switching noise. Filter component values must account for DI's 1.25–3.0 kΩ output impedance; lower R values improve bandwidth but increase loading on the DI driver.