Infineon Technologies IR3621M

Overview

IR3621M from Infineon Technologies is a dual-phase synchronous buck PWM controller with integrated high- and low-side gate drivers, supporting both independent dual-output and current-sharing single-output configurations. It operates at up to 500 kHz per phase, features two independent soft-starts (64 µA/28 µA current sources), pre-bias startup protection, and programmable hiccup/latched overcurrent response via MOSFET R_DS(on) sensing - used in DDR memory power delivery and graphics card VRMs.

For engineers reviewing the IR3621M datasheet, IR3621M pinout, IR3621M application, or IR3621M equivalent, key selection considerations include phase synchronization capability, DCR-based current sharing accuracy, V_REF = 0.8 V ±1%, thermal shutdown at 125°C, and MLPQ 5 mm × 5 mm 32-pin exposed-pad package compatibility with 4-layer PCB thermal design.

Technical Context

The IR3621M implements voltage-mode control with two independent error amplifiers (Comp1/Comp2), each driving a PWM comparator referenced to a shared 3 V ramp generator. Its dual-phase oscillator produces 180° out-of-phase clock signals, enabling interleaved operation that reduces input/output ripple current and capacitor stress.

Current sharing is achieved by configuring one channel as master (voltage regulation via Fb1) and the other as slave (current balancing via Fb2 and VP2), using either external sense resistors or inductor DCR networks. The Hiccup pin selects between latched shutdown (low) or auto-retry (high) fault recovery modes.

Key Specifications

Pinout & Package

IR3621M uses a thermally enhanced 32-pin MLPQ (5 mm × 5 mm) package with an exposed thermal pad connected to PGND. The package supports 4-layer PCB layout with vias under the pad for optimal junction-to-board thermal resistance (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 MP2940AGQSE and ISL6269CRZ, the IR3621M delivers superior thermal performance (θ_JA = 36°C/W), native DCR-based current sharing, and robust pre-bias handling - making it optimal for industrial and telecom PoL systems where reliability and analog flexibility are prioritized over digital configurability.

Availability

IR3621M is available at Aetrix Electronics and suitable for DDR memory power delivery, graphics card VRMs, and telecom point-of-load applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for IR3621M 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 IATF 16949.

The IR3621M belongs to Infineon's IR36xx dual-phase controller product line, engineered specifically for high-efficiency, high-current DC/DC conversion in networking, graphics, and memory subsystems where thermal density and transient response are critical.

FAQ

What is the minimum recommended external soft-start capacitor value for IR3621M?

The IR3621M's SS1 pin sources 64 µA and SS2 sources 28 µA. For a typical 10 ms soft-start time, use 150 nF on SS1 (64 µA × 10 ms ≈ 0.64 V across cap) and 330 nF on SS2. Capacitor tolerance must be ≤±10% C0G/NP0 ceramic to ensure monotonic ramp and avoid oscillation during startup.

Can IR3621M operate with only one phase active?

Yes - tie SS2 to VCC to disable Channel 2 while retaining full functionality of Channel 1. The IC automatically enters single-phase mode with doubled current capability per phase. However, interleaving benefits (reduced ripple, lower EMI) are lost, and thermal design must account for concentrated power dissipation in one driver pair.

How does the IR3621M implement DCR current sensing without external op-amps?

The IR3621M integrates dedicated current-sense amplifiers within its slave error amplifier path (E/A2). It accepts differential voltage from RC networks across inductor DCR, applies programmable gain via OCSet2 resistor, and compares the result to the internal ramp - eliminating need for external instrumentation amps while maintaining <±3% current matching accuracy.

What is the maximum allowable voltage on the HDrv pins relative to PGnd?

HDrv1 and HDrv2 pins tolerate up to 25 V relative to their respective PGnd1/PGnd2 pins, but operational specification limits VcH1/VcH2 to 10–20 V. Exceeding 20 V risks exceeding the absolute maximum rating and may cause premature gate oxide degradation in connected MOSFETs - always verify bootstrap capacitor voltage rating and diode forward drop.