IFX80471 Step-Down DC/DC Controller IFX80471SKV IFX80471SKV50 Data Sheet Rev. 1.0, 2011-02-07 Standard Power IFX80471 Table of Contents Table of Contents 1 Overview . 3 2 Block Diagram . 4 3 Pin Configuration 5 3.1 Pin Assignment . 5 3.2 Pin Definitions and Functions 5 4 General Product Characteristics 7 4.1 Absolute Maximum Ratings . 7 4.2 Functional Range . 8 4.3 Thermal Resistance . 9 5 Electrical Characteristics . 10 5.1 Electrical Characteristics 10 5.2 Typical Performance Characteristics . 15 6 Detailed Circuit Description . 19 6.1 PFM/PWM Step-down regulator . 19 6.2 Battery voltage sense . 20 6.3 Undervoltage Reset 20 7 Application Information 21 7.1 General 21 7.2 Output voltage at adjustable version - feedback divider . 21 7.3 SI Enable 21 7.3.1 Battery sense comparator - voltage divider . 22 7.4 Undervoltage reset - delay time . 22 7.5 100% duty-cycle operation and dropout . 22 7.6 SYNC Input and Frequency Control 23 7.7 Shutdown Mode . 23 7.8 Buck converter circuit . 23 7.8.1 Buck inductance (L1) selection in terms of ripple current: 23 7.8.2 Determining the current limit 24 7.8.3 PFM and PWM thresholds 24 7.8.4 Buck output capacitor (COUT) selection: 24 7.8.5 Input capacitor (CIN1) selection: . 25 7.8.6 Freewheeling diode / catch diode (D1) 25 7.8.7 Buck driver supply capacitor (CBDS) . 25 7.8.8 Input pi-filter components for reduced EME 25 7.8.9 Frequency compensation 25 7.9 Components recommendation - Overview . 26 7.10 Layout recommendation . 26 8 Package Outlines . 28 9 Revision History 29 Data Sheet 2 Rev. 1.0, 2011-02-07