Infineon Technologies IR3821MTR1PBF

Overview

IR3821MTR1PBF from Infineon Technologies is a highly integrated synchronous buck regulator with 7A continuous output current, 2.5V–21V input voltage range, and 0.6V–12V programmable output voltage. It integrates high- and low-side MOSFETs, PWM controller, and error amplifier in a thermally enhanced 5mm×6mm QFN-15 package, targeting DDR memory and graphics card voltage regulation.

For engineers reviewing the IR3821MTR1PBF datasheet, IR3821MTR1PBF pinout, IR3821MTR1PBF application, or IR3821MTR1PBF equivalent, key selection criteria include its fixed 600kHz switching frequency, programmable hiccup over-current protection, pre-bias start-up capability, and precision 0.6V reference with ±1.5% accuracy over –40°C to +105°C.

Technical Context

The IR3821MTR1PBF implements voltage-mode PWM control with a fixed 600kHz oscillator and internal linear sawtooth ramp generator. Its error amplifier features 1000–1600 μmho transconductance and supports external compensation via COMP pin.

Over-current protection uses R_DS(on)-based sensing of the low-side MOSFET (10.5–13.4 mΩ typ.), eliminating external sense resistors. Thermal shutdown activates at 140°C with 20°C hysteresis, and UVLO monitors both VCC (4.0–4.4V turn-on) and VC (3.1–3.5V turn-on) supplies independently.

Key Specifications

Pinout & Package

Package: 5mm × 6mm Power QFN-15 with exposed thermal pad (PGnd-connected), RoHS-compliant, moisture sensitivity level 3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck regulator applications.

Compared with MP2315DJ-LF-Z and TPS54360BDDAR, the IR3821MTR1PBF uniquely delivers 7A continuous current in an integrated 15-pin QFN with dedicated VC/HG pins, hiccup OCP, and pre-bias start-up-making it optimal for space-constrained, high-density DDR and GPU power delivery where full integration and robust fault handling are critical.

Availability

IR3821MTR1PBF is available at Aetrix Electronics and suitable for DDR memory power supplies, graphics card core regulation, and server point-of-load converters requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for IR3821MTR1PBF 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 and IECQ QC 080000.

The IR3821 belongs to Infineon's SupIRBuck™ family-designed specifically for high-efficiency, space-constrained DC/DC conversion in computing and communications infrastructure where integration, thermal performance, and programmability are essential.

FAQ

What is the maximum allowable junction temperature for continuous 7A operation?

The IR3821MTR1PBF specifies a maximum operating junction temperature of 125°C. At 7A output, thermal design must ensure θ_JA ≤ 40°C/W using a 2oz copper 4-layer PCB with thermal vias under the exposed PGnd pad. Derating is required above 125°C; thermal shutdown activates at 140°C with 20°C hysteresis.

Can the IR3821MTR1PBF start up into a pre-biased output, and how is it implemented?

Yes-the IR3821MTR1PBF supports pre-bias start-up by disabling the synchronous rectifier until the first control MOSFET gate pulse is generated. This prevents reverse current flow into a charged output capacitor. The feature is automatic and requires no external configuration; it is confirmed in the device's circuit description and Figure 4 of the datasheet.

How is over-current protection configured, and what happens during a fault?

Over-current protection is set by a resistor between OCSet and SW pins, which programs the hiccup current limit threshold. During a fault, the device enters hiccup mode: it shuts down, waits ~15ms, then attempts restart. If the fault persists, cycling repeats. This behavior is documented in the Electrical Specifications table and Circuit Description section.

Is the PGood signal active-high or open-drain, and how is its threshold adjusted?

The PGood pin is open-drain and requires an external pull-up resistor to VCC. Its activation threshold is set by the voltage on the Vsns pin, which is compared to an internal 0.38V reference. A resistor divider from output to AGnd and Vsns to AGnd programs the trip point; hysteresis is fixed at 15–40mV per the datasheet.