Infineon Technologies IR3621FTR

Overview

IR3621FTR 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 R_DS(on) or DCR sensing - deployed in DDR memory power supplies and graphics card VRMs.

For engineers reviewing the IR3621FTR datasheet, IR3621FTR pinout, IR3621FTR application, or IR3621FTR equivalent, this page delivers verified functional identity, validated 28-pin TSSOP package mapping, confirmed 180° out-of-phase timing architecture, real-world current-sharing implementation using inductor DCR, and precise soft-start sequencing behavior - all critical for point-of-load power integrity validation.

Technical Context

The IR3621FTR implements voltage-mode control with two independent error amplifiers (Comp1/Comp2), each feeding a dedicated PWM comparator driven by a shared ramp generator with 180° phase offset. Its oscillator supports external synchronization (Sync pin) and frequency setting via Rt resistor (200–500 kHz), while VP2 provides a 0.8 V precision reference with ±1% accuracy over temperature.

Current sharing is achieved through master-slave loop configuration: Fb1 sets output voltage via resistive divider; Fb2 senses current imbalance via DCR or sense resistor and adjusts duty cycle to equalize inductor currents. Pre-bias startup prevents reverse discharge by clamping drivers until SS pins reach threshold, and thermal shutdown triggers at 150°C with 20°C hysteresis.

Key Specifications

Pinout & Package

IR3621FTR uses a 28-pin TSSOP package (5.0 mm × 4.4 mm, 0.65 mm pitch) with exposed thermal pad connected to PGND. Pin 1 is marked by dot; pin count and orientation follow JEDEC MO-153 standard. The package supports 2.5 W power dissipation with θ_JA = 36.0°C/W on 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL6322IRZ-T and TPS546B24ARVFT, the IR3621FTR offers analog simplicity, proven pre-bias robustness for memory rails, and cost-effective integration of drivers - making it optimal for fixed-function, high-reliability embedded power where digital overhead is unnecessary.

Availability

IR3621FTR is available at Aetrix Electronics and suitable for graphics card VRMs, DDR memory power supplies, distributed telecom PoL architectures, and embedded networking switches requiring stable component supply across long production cycles.

Supply support for IR3621FTR 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 electronics, and industrial control ICs, with global manufacturing and quality certification to ISO/TS 16949.

The IR3621 belongs to Infineon's iPOWER™ analog controller family, designed specifically for high-efficiency, multi-phase DC/DC conversion in computing and communications infrastructure where reliability and thermal performance are critical.

FAQ

What is the maximum supported input voltage for V_cH1 and V_cH2?

V_cH1 and V_cH2 accept 10–20 V per the Recommended Operating Conditions table. Absolute maximum rating is 25 V, but sustained operation above 20 V risks accelerated gate oxide degradation in the integrated drivers. For 12 V input systems, 12 V is recommended to ensure margin against transients and maintain driver efficiency.

Can IR3621FTR operate in single-phase mode?

No - the IR3621FTR is architecturally dual-phase only. It does not support disabling one phase; both HDrv1/LDrv1 and HDrv2/LDrv2 are always active. However, in independent dual-output mode, Phase 1 and Phase 2 can regulate different voltages (e.g., 1.8 V and 3.3 V) with separate feedback networks.

How is current sharing accuracy affected by inductor DCR tolerance?

With ±10% DCR tolerance, current sharing imbalance remains within ±3% across load range, as confirmed in Figure 5 test data. Matching inductors from same batch improves balance to ±1.5%. External sense resistors (0.5% tolerance) reduce imbalance to <±0.5%, but add conduction loss.

Is the VOUT3 LDO output internally current-limited?

Yes - the VOUT3 regulator is short-circuit protected and delivers up to 40 mA continuously. Internal current limiting activates at ~60 mA, clamping output voltage to ~3 V to prevent thermal runaway. A 1 µF ceramic capacitor is mandatory for stability per Figure 12 layout guidelines.