Infineon Technologies IR3856MTR1PBF

Overview

IR3856MTR1PBF from Infineon Technologies is a highly integrated 6A synchronous buck regulator with co-packaged high- and low-side MOSFETs, PWM controller, bootstrap diode, and precision 0.7V ±1% reference. It operates from 1.5V to 21V input, delivers 0.7V–0.9×Vin output, supports up to 1.5MHz switching, and targets point-of-load power delivery in server VRMs and telecom DC-DC converters.

For engineers reviewing the IR3856MTR1PBF datasheet, IR3856MTR1PBF pinout, IR3856MTR1PBF application, or IR3856MTR1PBF equivalent, key selection factors include programmable hiccup current limit (20.8–172 µA OCSET range), dedicated voltage monitoring on Vsns and Enable pins, thermal shutdown at 140°C, and 4mm × 5mm Power QFN-17 package with exposed thermal pad.

Technical Context

The IR3856 implements a voltage-mode PWM control architecture with an integrated error amplifier (GBWP = 20–40 MHz, slew rate = 7–20 V/µs) and programmable oscillator (Rt-based, 225–1650 kHz). Its dual-MOSFET power stage features R_DS(on) of 22–29 mΩ (top) and 13.4–19 mΩ (bottom) at T_j = 25°C, enabling >95% peak efficiency at 6A/1.8V out from 12V input.

Protection logic includes overvoltage detection on Vsns (trip at 110–120% V_REF), PGood comparator with 256/F_s delay, and pre-bias start-up support. The Seq pin enables tracking sequencing, while Sync allows external clock synchronization across multiple POL regulators.

Key Specifications

Pinout & Package

IR3856MTR1PBF uses a 4mm × 5mm Power QFN-17 package with exposed thermal pad connected to PGND. Pin 17 is Gnd (signal ground); pin 11 is PGnd (power ground); pin 14 is Boot (requires 0.1µF capacitor to SW); and pin 12 is SW (switch node, connects to output inductor).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2451DT-LF-Z and TPS54620RGYR, IR3856MTR1PBF offers the only fully integrated 6A solution with Seq, Sync, and pre-bias start-up in a 4mm × 5mm footprint - making it optimal for dense, multi-rail telecom and server POL designs where layout simplicity and sequencing control are critical.

Availability

IR3856MTR1PBF is available at Aetrix Electronics and suitable for server VRMs, telecom point-of-load converters, and embedded networking modules requiring stable component supply, long-lifecycle availability, and RoHS-compliant packaging.

Supply support for IR3856MTR1PBF 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 global manufacturing and quality certification to ISO/TS 16949 and IECQ QC 080000.

The SupIRBuck™ product line delivers fully integrated, high-current DC/DC buck regulators targeting space-constrained, high-efficiency point-of-load applications in datacenter, telecom, and enterprise storage systems.

FAQ

What is the minimum recommended output capacitance for stable 6A operation?

The IR3856MTR1PBF datasheet specifies a minimum 220µF total output capacitance using low-ESR ceramic or polymer capacitors. This value ensures <1% output voltage deviation during 6A step-load transients and maintains phase margin above 45° across –40°C to +125°C. Layout must minimize trace inductance between PGND and output cap ground pads.

Can the IR3856MTR1PBF operate with a 24V input?

No - the absolute maximum VIN rating is 25V, but the recommended operating range is limited to 1.5V–21V per datasheet Section 5. Exceeding 21V risks exceeding internal gate oxide limits on the integrated high-side MOSFET and may trigger premature thermal shutdown. For 24V systems, a front-end pre-regulator or alternative 36V-rated buck controller is required.

How does the hiccup current limit behave during sustained overload?

When OCSet threshold is exceeded, the IR3856MTR1PBF enters hiccup mode: it disables switching for 4096 clock cycles (~8ms at 500kHz), then attempts automatic restart. This cycle repeats until fault clears. Unlike latch-off protection, hiccup mode prevents thermal runaway while allowing system-level fault recovery without manual reset.

Is the exposed thermal pad electrically connected internally?

Yes - the exposed thermal pad on the underside of the IR3856MTR1PBF Power QFN package is internally connected to PGND (Pin 11). It must be soldered to a dedicated 4-layer PCB copper pour tied to the power ground plane with ≥4 thermal vias (0.3mm diameter, 0.8mm pitch) to achieve θ_JA = 45°C/W and sustain 6A continuous operation at 125°C ambient.