Infineon Technologies IR3821MTRPBF

Overview

IR3821MTRPBF from Infineon Technologies is a highly integrated synchronous buck regulator with integrated high- and low-side MOSFETs, delivering continuous 7A output current across 0.6V–12V output range from 2.5V–21V input. It features fixed 600kHz switching frequency, programmable over-current protection via OCSet pin, precision 0.6V reference (±1.5% over –40°C to +105°C), and pre-bias start-up-designed for DDR memory, graphics card, and server point-of-load applications.

For engineers reviewing the IR3821MTRPBF datasheet, IR3821MTRPBF pinout, IR3821MTRPBF application, or IR3821MTRPBF equivalent, key selection considerations include its thermally enhanced 5mm×6mm QFN-15 package, dual UVLO thresholds (VCC_UVLO=4.0–4.4V, VC_UVLO=3.1–3.5V), hiccup-mode current limiting, and open-drain PGood output with externally adjustable trip threshold via Vsns.

Technical Context

The IR3821MTRPBF implements voltage-mode PWM control with a fixed 600kHz oscillator and internal sawtooth ramp generator, eliminating external timing components. Its error amplifier (gm = 1000–1600 µmho) compares FB voltage against a 0.6V reference, driving gate drivers through COMP output.

Current sensing uses R_DS(on) of the integrated low-side MOSFET (10.5–13.4 mΩ at 6A, 25°C), enabling resistorless over-current protection set via OCSet-to-SW resistor. Thermal shutdown triggers at 140°C with 20°C hysteresis, and pre-bias startup avoids output disturbance when powering into charged capacitors.

Key Specifications

Pinout & Package

Package: 5mm × 6mm Power QFN-15 with exposed thermal pad (pin 15 is AGnd; pins 4, 5, and 15 must be connected together on 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 TPS54560BQPWPRQ1, the IR3821MTRPBF delivers higher current density (7A in 5mm×6mm), eliminates external power components, and provides critical system features like pre-bias start-up and dual UVLO-making it optimal for high-density computing and graphics applications where integration and robustness are prioritized over ultra-wide input range or automotive qualification.

Availability

IR3821MTRPBF is available at Aetrix Electronics and suitable for DDR memory power delivery, graphics card core regulation, and server point-of-load conversion requiring stable component supply, full production traceability, and long-term lifecycle support.

Supply support for IR3821MTRPBF 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 global semiconductor leader specializing in power management, automotive, and industrial control ICs, with decades of expertise in high-efficiency power conversion and silicon-based power stages.

The IR3821 belongs to Infineon's SupIRBuck™ family-engineered specifically for high-current, space-constrained point-of-load applications in computing, networking, and graphics, emphasizing integration, thermal performance, and system-level protection.

FAQ

What is the recommended PCB layout practice for AGnd and PGnd connections?

AGnd (pins 4, 5, 15) must form a low-impedance star connection near the IC, isolated from high-current PGnd traces. PGnd (pin 10) should connect directly to the power inductor's ground pad and the thermal pad via multiple vias. Never tie AGnd and PGnd together on the IC side-join them at a single point near the input bulk capacitor to avoid noise coupling into feedback and soft-start circuits.

How is over-current protection configured using the OCSet pin?

A resistor from OCSet (pin 7) to SW (pin 11) sets the current limit threshold. The relationship is I_LIM ≈ 0.02V / R_OCSET, where 0.02V is the internal sense voltage across the low-side MOSFET's R_DS(on). For example, a 10kΩ resistor yields ~2A limit; a 1kΩ resistor yields ~20A-though thermal limits constrain practical maximum to 7A continuous.

Can the IR3821MTRPBF operate with an input voltage below 4.5V?

Yes-the absolute minimum VIN is 2.5V per Absolute Maximum Ratings, and the device functions down to this level. However, VCC and VC supplies must remain within their respective UVLO windows: VCC ≥ 4.0V and VC ≥ 3.1V. At VIN < 4.5V, ensure external VCC and VC bias sources meet these thresholds, as internal generation may not sustain regulation.

What is the purpose of the separate Vsns and FB pins?

Vsns (pin 1) and FB (pin 2) serve independent roles: FB sets output voltage via resistor divider and closes the regulation loop, while Vsns feeds the PGood comparator for independent rail monitoring. This separation allows redundant voltage verification-e.g., FB can be tuned for accuracy, while Vsns uses a separate divider to trigger PGood at 95% of nominal output, enabling safe system boot sequencing without relying on the regulation loop.