Infineon Technologies IR3856MTRPBF

Overview

IR3856MTRPBF from Infineon Technologies is a highly integrated 6A synchronous buck regulator with co-packaged high- and low-side MOSFETs, PWM controller, and bootstrap diode in a 4mm × 5mm Power QFN-17 package. It delivers 0.7V–0.9×Vin output across 1.5V–21V input, supports up to 1.5MHz switching, and achieves >95% peak efficiency at 1.8V/6A (Vin=12V). Used in server VRMs and telecom POL rails requiring precise low-voltage regulation.

For engineers reviewing the IR3856MTRPBF datasheet, IR3856MTRPBF pinout, IR3856MTRPBF application, or IR3856MTRPBF equivalent, key selection criteria include programmable current limit via OCSet, dedicated voltage monitoring on Vsns, PGood with 80–90% Vref threshold, and thermal shutdown at 140°C junction temperature.

Technical Context

The IR3856 implements a current-mode control architecture with a high-bandwidth error amplifier (GBWP = 20–40 MHz, slew rate = 7–20 V/μs) and internal ramp compensation. Its oscillator supports resistor-programmed frequency (225–1650 kHz) and external synchronization over the same range.

Protection logic includes hiccup-mode overcurrent (4096-cycle off-time), overvoltage (110–120% Vref trip), and precision enable/UVLO thresholds (Enable_UVLO_Start = 1.14–1.36V, Vcc_UVLO_Start = 3.95–4.35V), all operating across –40°C to +125°C junction temperature.

Key Specifications

Pinout & Package

IR3856MTRPBF uses a 4mm × 5mm Power QFN-17 package with exposed thermal pad connected to PGND. Pin 11 (PGnd) and Pin 17 (Gnd) are separated for optimal power/ground isolation; the exposed pad must be soldered to ≥2 oz. copper on a 4-layer PCB.

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 TPS546B24RVFT, the IR3856MTRPBF offers superior integration (integrated bootstrap diode, co-packaged FETs), wider input range (1.5–21V), and analog programmability (Rt, OCSet, SS) ideal for fixed-function, space-constrained POL designs where digital control adds unnecessary overhead.

Availability

IR3856MTRPBF is available at Aetrix Electronics and suitable for server VRMs, telecom POL rails, and embedded networking equipment requiring stable component supply, extended temperature operation (–40°C to +125°C), and RoHS-compliant packaging.

Supply support for IR3856MTRPBF 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 leader specializing in power management, automotive ICs, and industrial control solutions, with global manufacturing and quality certification to ISO/TS 16949 and IECQ QC 080000.

The SupIRBuck™ product line delivers fully integrated, high-current synchronous buck regulators targeting distributed point-of-load architectures in datacenter, telecom, and computing infrastructure where efficiency, thermal performance, and layout simplicity are critical.

FAQ

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

The IR3856MTRPBF datasheet specifies a minimum 220μF total output capacitance using low-ESR polymer or MLCC-based arrays. At 6A load, ≥470μF is recommended to maintain <1% output deviation during 4A/μs transients and meet PGood assertion timing (256/Fs delay). Layout must minimize loop inductance with direct capacitor placement near PGnd and SW pins.

Can the IR3856MTRPBF operate with an input voltage below 4.5V?

Yes - the device supports input voltages as low as 1.5V, but Vcc must be independently supplied within 4.5–5.5V per recommended operating conditions. Below 4.5V Vcc, internal logic and gate drive performance degrades; use a dedicated LDO or charge pump to maintain Vcc if Vin falls below 4.5V.

How is overcurrent protection configured and what happens during fault?

OCSet pin voltage relative to SW sets current limit threshold; typical configuration uses a 10kΩ resistor for ~50A/V scaling. During overcurrent, the device enters hiccup mode: it shuts down for 4096 switching cycles (≈8ms at 500kHz), then attempts restart. This prevents thermal runaway while allowing automatic recovery after fault removal.

Is the exposed thermal pad electrically connected, and how should it be routed?

Yes - the exposed pad is internally connected to PGnd (Pin 11) and must be soldered to a dedicated PGnd copper pour on layer 2 or 3. Use ≥4 thermal vias (0.3mm diameter) filled with solder to connect to inner-layer PGnd planes. Do not tie the pad to signal Gnd (Pin 4/17); separation preserves power/ground noise isolation critical for regulation accuracy.