IR3447A IRA OptiMOS IPOL 25 A single-voltage synchronous Buck regulator Features Single 4.3 V to 17 V application or Wide Input Voltage Range from 2 V to 17 V with external VCC Precision Reference Voltage (0.6 V +/-0.5%) Enhanced Fast COT engine stable with Ceramic Output Capacitors and No External Compensation Switching Frequency of 600 kHz with Forced Continuous Conduction Mode Enable input with Voltage Monitoring Capability & Power Good Output Monotonic Start-Up with 2 ms soft start time & Enhanced Pre-Bias Start up Thermally compensated Internal Over Current Protection with two Selectable Settings Thermal Shut Down o o Operating Junction Temp: -40 C < T < 125 C j Small Size: 5 mm x 6 mm PQFN Halogen-free and RoHS2 Compliant with Exemption 7a Potential applications Server Applications Storage Applications Telecom & Datacom Applications Distributed Point of Load Power Architectures Product validation Qualified for industrial applications according to the relevant tests of JEDEC47/20/22 Description The IR3447A is an easy-to-use, fully integrated dc - dc Buck regulator. The onboard PWM controller and MOSFETs with integrated bootstrap diode make IR3447A a small footprint solution, providing high-efficiency power delivery. Furthermore, it uses a fast Constant On-Time (COT) control scheme, which simplifies design efforts and provides fast control response. The IR3447A has an internal low dropout voltage regulator, allowing operation with a single supply. It can also operate with an external bias supply, extending the operating input voltage (PVIN) range. The IR3447A offers a switching frequency of 600 kHz, two selectable current limits, soft start time of 2 ms, and Forced Continuous Conduction Mode (FCCM). It also features important protection functions, such as pre-bias start-up, thermally compensated current limits, over voltage and under voltage protection, and thermal shutdown to give required system level security in the event of fault conditions. Final Datasheet Please read the Important Notice and Warnings at the end of this document V 2.4 www.infineon.com Page 1 of 40 2021-11-19 IRA OptiMOS IPOL 25 A single-voltage synchronous Buck regulator Table of contents Table of contents Features ........................................................................................................................................ 1 Potential applications ..................................................................................................................... 1 Product validation .......................................................................................................................... 1 Description .................................................................................................................................... 1 Table of contents ............................................................................................................................ 2 1 Ordering information ............................................................................................................. 4 2 Functional block diagram ........................................................................................................ 5 3 Typical application diagram .................................................................................................... 6 4 Pin descriptions ..................................................................................................................... 7 5 Absolute maximum ratings ..................................................................................................... 9 6 Thermal Characteristics ......................................................................................................... 10 6.1 Thermal Characteristics ........................................................................................................................ 10 7 Electrical specifications ......................................................................................................... 11 7.1 Recommended operating conditions ................................................................................................... 11 7.2 Electrical characteristics ....................................................................................................................... 12 8 Typical efficiency and power loss curves .................................................................................. 14 8.1 PVIN = VIN = 12 V, F = 600 kHz, Mode: FCCM ....................................................................................... 14 sw 9 Thermal de-rating cuves ........................................................................................................ 15 10 R of MOSFET over temperature ......................................................................................... 16 DS(ON) 11 Typical operating characteristics (-40 C T + C) .............................................................. 17 j 12 Theory of operation ............................................................................................................... 19 12.1 Fast Constant On-Time Control ............................................................................................................ 19 12.2 Enable .................................................................................................................................................... 19 12.3 FCCM and DEM Operation ..................................................................................................................... 20 12.4 Pseudo-Constant Switching Frequency ............................................................................................... 20 12.5 Soft-start ................................................................................................................................................ 20 12.6 Pre-bias Start-up ................................................................................................................................... 20 12.7 Internal Low Dropout (LDO) Regulator .............................................................................................. 21 12.8 Over Current Protection (OCP) ............................................................................................................. 21 12.9 Under Voltage Protection (UVP) ........................................................................................................... 22 12.10 Over Voltage Protection (OVP) .............................................................................................................. 22 12.11 Over Temperature Protection (OTP) .................................................................................................... 23 12.12 Power Good (PGood) Output ................................................................................................................ 23 12.13 Minimum ON Time and Minimum OFF Time ................................................................................... 24 12.14 Selection of Feedforward Capacitor and Feedback Resistors ............................................................. 24 13 Design example ..................................................................................................................... 26 13.1 Enabling the IR3447A ............................................................................................................................ 26 13.2 Selecting Input Capacitors .................................................................................................................... 26 13.3 Inductor Selection ................................................................................................................................. 27 13.4 Output Capacitor Selection .................................................................................................................. 27 13.5 Output Voltage Programming............................................................................................................... 28 13.6 Feedforward Capacitor ......................................................................................................................... 28 13.7 Bootstrap Capacitor .............................................................................................................................. 28 13.8 VIN and VCC/LDO bypass Capacitor ..................................................................................................... 28 Final Datasheet 2 of 40 V 2.4 2021-11-19