Infineon Technologies IR3865MTR1PBF

Overview

IR3865MTR1PBF from Infineon Technologies is a highly integrated synchronous buck regulator with integrated high- and low-side MOSFETs, constant on-time hysteretic control, and 10A continuous output current capability. It operates from 3V to 21V input, delivers 0.5V–12V output with ±1% reference accuracy, and features programmable switching frequency (up to 750 kHz), thermally compensated overcurrent protection, and power good output - used in notebook CPU core voltage regulation.

For engineers reviewing the IR3865MTR1PBF datasheet, IR3865MTR1PBF pinout, IR3865MTR1PBF application, or IR3865MTR1PBF equivalent, key selection considerations include its 17-pin 4mm × 5mm QFN package, FCCM/DCM mode control via dedicated pin, ISET-based current limit programming, and enable input with voltage monitoring for system-level power sequencing.

Technical Context

The IR3865MTR1PBF implements a constant on-time (COT) hysteretic control architecture that eliminates external compensation components and enables fast transient response without loop stability tuning. Its internal gate drivers support bootstrapped high-side FET operation with 300 mV PFET forward voltage and 5–30 ns deadtime control.

It integrates dual MOSFETs with R_DS(on) of 23–28 mΩ (high-side) and 10.7–13 mΩ (low-side) at 25°C, enabling high-efficiency conversion across light to full load. The device supports pre-bias startup, forced CCM operation, and thermal shutdown at 125–140°C with 20°C hysteresis.

Key Specifications

Pinout & Package

IR3865MTR1PBF is housed in a thermally enhanced 4mm × 5mm, 17-pin Power QFN package with exposed thermal pad (PGND-connected) and 0.5 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2315DJ-LF-Z and TPS546B24RVFT, the IR3865MTR1PBF offers optimal balance of integration, analog simplicity, and 10A capability in a compact footprint - ideal for analog-controlled, high-reliability computing and consumer POL designs where digital overhead is unnecessary.

Availability

IR3865MTR1PBF is available at Aetrix Electronics and suitable for notebook CPU core regulation, desktop GPU power delivery, and industrial embedded controller rails requiring stable component supply, long-term lifecycle support, and qualified MSL2 moisture sensitivity handling.

Supply support for IR3865MTR1PBF 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 German semiconductor manufacturer specializing in power management, automotive, and industrial control ICs, with leadership in silicon and silicon carbide power devices.

The IR3865 belongs to Infineon's SupIRBuck™ family - designed specifically for high-density, high-efficiency point-of-load regulation in computing and consumer electronics where integration, thermal performance, and analog control simplicity are critical.

FAQ

What is the recommended PCB layout practice for the PHASE pin?

The PHASE pin connects directly to the high- and low-side MOSFET source/drain nodes and carries high dv/dt switching current. Place the input capacitor (C_IN) as close as possible to VIN and PGND pins, route PHASE with minimum loop area, and avoid routing sensitive analog traces (FB, SS, ISET) near it. Use solid PGND plane beneath the IC and stitch thermal pad to PGND with ≥6 vias.

How is the overcurrent threshold set using the ISET pin?

The ISET pin sinks current proportional to the PHASE node voltage during on-time. Connect a resistor from ISET to PHASE to set the current limit: R_ISET = V_PHASE / I_ISET, where I_ISET is 19 µA typical at 25°C and varies with temperature (4400 ppm/°C). This method eliminates external current-sense resistors and provides inherent thermal compensation.

Does the IR3865MTR1PBF support output voltages below 0.5V?

No - the internal 0.5V reference is trimmed to ±1% and is the minimum feedback voltage. The device cannot regulate below 0.5V because the FB comparator input is referenced to this internal bandgap. For sub-0.5V outputs, an external reference or different controller architecture would be required.

Can the SS pin be left floating?

No - the SS pin must be either connected to GND (for immediate startup) or to an external capacitor (for programmable soft-start). Leaving it floating may cause unpredictable startup behavior or failure to enable due to noise susceptibility. A 100 nF capacitor yields ~1 ms ramp time; larger values extend soft-start duration linearly.