Infineon Technologies IR3621MTR

Overview

IR3621MTR from Infineon Technologies is a dual-phase synchronous buck PWM controller with integrated high- and low-side drivers, supporting both independent dual-output (e.g., 1.2V + 1.8V) and current-sharing single-output (up to 60A+) configurations. It operates at up to 500 kHz per phase, features two independent soft-starts, pre-bias startup, and programmable hiccup/latched overcurrent protection - deployed in DDR memory power delivery and graphics card VRMs.

For engineers reviewing the IR3621MTR datasheet, IR3621MTR pinout, IR3621MTR application, or IR3621MTR equivalent, key selection considerations include its 180° out-of-phase operation for reduced input/output capacitance, DCR-based current sharing without sense resistors, VREF accuracy of ±1%, and thermal shutdown at 125°C with 18°C hysteresis.

Technical Context

The IR3621MTR implements voltage-mode control with two independent error amplifiers and a dual-ramp oscillator generating precisely 180° phase-shifted timing signals. Each channel uses dedicated compensation pins (Comp1/Comp2), feedback inputs (Fb1/Fb2), and current-limit programming via OCSet1/OCSet2 using MOSFET R_DS(on) sensing.

Its mode selection is hardware-defined: SS2 floating enables current-share mode (one master, one slave loop); SS2 tied to capacitor enables independent dual-output mode. Pre-bias startup prevents output discharge during hot-insertion, and the internal 6.2V VOUT3 LDO powers external gate drivers or charge pumps.

Key Specifications

Pinout & Package

The IR3621MTR is housed in a thermally enhanced 32-pin MLPQ (5 mm × 5 mm) package with exposed thermal pad. The package supports 4-layer PCB layout with vias to inner ground plane for θ_JA = 36.0°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.

Compared with MP8765GQ and ISL95831, the IR3621MTR uniquely balances analog flexibility (R_DS(on) current sensing, dual soft-start, pre-bias) with high-current analog VRM performance-making it optimal for DDR, GPU, and embedded ASIC power where digital control adds complexity without benefit.

Availability

IR3621MTR is available at Aetrix Electronics and suitable for graphics card VRMs, DDR memory power delivery, distributed telecom point-of-load systems, and embedded networking switch ASICs requiring stable component supply across long production lifecycles.

Supply support for IR3621MTR 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 high-efficiency DC-DC controllers and silicon carbide solutions.

The IR3621 belongs to Infineon's legacy analog multiphase controller product line, designed specifically for high-current, low-voltage point-of-load applications in computing and communications infrastructure where analog precision and reliability are prioritized over digital configurability.

FAQ

What is the function of the VOUT3 pin on the IR3621MTR?

VOUT3 is the output of an internal 6.2 V LDO regulator capable of supplying up to 40 mA. It is designed to power external high-side gate drivers or charge pump circuits, eliminating the need for a separate bias supply. The LDO is short-circuit protected and internally decoupled; a 1.0 µF ceramic capacitor must be placed between VOUT3 and ground for stability.

How does the IR3621MTR implement current sharing without external sense resistors?

The IR3621MTR uses MOSFET R_DS(on) sensing via OCSet1/OCSet2 pins to measure current in each phase. A resistor from OCSet to the switching node sets the current threshold based on R_DS(on) voltage drop. In current-share mode, one channel acts as master (voltage control), the other as slave (current balancing), using DCR or R_DS(on) to match average inductor currents without added loss or board area.

Can the IR3621MTR operate with only one phase active?

No - the IR3621MTR is a dual-phase controller with fixed 180° interleaving and no single-phase disable mode. Both phases must be configured and populated. However, in independent dual-output mode, each phase controls a separate rail (e.g., 1.2 V and 1.8 V), and their outputs are electrically isolated; neither phase relies on the other for timing or regulation.

What is the purpose of the Hiccup pin, and how should it be configured?

The Hiccup pin (Pin 28) selects overcurrent protection behavior: pulled high (≥2.5 V) enables hiccup mode (auto-retry after fault), pulled low (≤0.8 V) enables latched shutdown (requires Vcc cycle or SS pin reset). This pin directly configures fault recovery strategy - critical for systems where continuous retry could damage loads, or where automatic recovery improves uptime without host intervention.