DATASHEET ISL78268 FN8657 Rev 3.00 55V Synchronous Buck Controller with Integrated 3A Driver December 12, 2014 The ISL78268 is a grade 1, automotive, synchronous buck Features controller with integrated high/low side MOSFET drivers. It Wide input range 5V to 55V (switching) withstand 60V supports a wide operating input voltage range of 5V to 55V (non-switching) and up to 60V at V when not switching. The integrated driver IN offers adaptive dead-time control and is capable of supplying Integrated 2A sourcing, 3A sinking MOSFET drivers up to 2A sourcing and 3A sinking current, allowing the Constant current regulation/limiting - dedicated average ISL78268 to support power stages designed for a wide range current control loop of loads, from under 1A to over 25A. Adjustable switching frequency or external synchronization from 50kHz up to 1.1MHz ISL78268s fully synchronous architecture enables power conversion with very high efficiency and improved thermal Low shutdown current, I <1A Q performance over standard buck converters. The ISL78268 also Peak current mode control with adjustable slope offers diode emulation mode for improved light load efficiency. compensation While ISL78268 is a peak current mode PWM controller, it Selectable diode emulation mode for high efficiency at light also includes a dedicated average output current modulation load loop, which achieves constant output current limiting for Input and output OVP, cycle-by-cycle current limiting, applications such as battery charging, super-cap charging, and average current OCP, OTP temperature control systems where a constant current must Selectable hiccup or latch-off fault responses be provided. Pb-free 24 Ld 4x4 QFN package (RoHS compliant) The ISL78268 supports switching frequencies from 50kHz to AEC-Q100 qualified 1.1MHz allowing the user the flexibility to trade-off switching frequency and efficiency against the size of external Applications components. Automotive power The ISL78268 offers comprehensive protection features. It Telecom and industrial power supplies includes robust current protection with cycle-by-cycle peak General purpose power current limiting, average current limiting, and a selectable Supercap charging hiccup or latch-off fault responses. In addition, it offers protection against over-temperature, as well as input and output overvoltages. Related Literature AN1946, ISL78268EVAL1Z Evaluation Board User Guide VIN VIN EN EN IC ISEN1P 100 VCC PVCC ISEN1N 95 PVCC PVCC 90 IMON/DE 85 V = 15V BOOT IN V = 24V IN 80 FSYNC UG V = 36V IN VOUT ISL78268 PLL COMP 75 PH LG 70 V = 55V IN SLOPE 65 ISEN2P ISEN2N COMP 60 SS FB 55 VCC V = 12V, T = +25C OUT A CLKOUT POWER GOOD 50 HIC/LATCH PGOOD 012345 SGND PGND I (A) OUT FIGURE 1. SIMPLIFIED TYPICAL APPLICATION SCHEMATIC FIGURE 2. EFFICIENCY CURVES (ISL78268EVAL1Z/DE MODE) FN8657 Rev 3.00 Page 1 of 34 December 12, 2014 EFFICIENCY (%)ISL78268 Table of Contents Related Literature . 1 Pin Configuration 3 Functional Pin Description 3 Ordering Information 5 Block Diagram 6 Typical Application Schematics 7 Absolute Maximum Ratings 10 Thermal Information 10 Recommended Operating Conditions . 10 Electrical Specifications 10 Typical Performance 14 Operation Description . 20 Synchronous Buck . 20 Adaptive Dead-Time Control . 20 Operation Initialization and Soft-Start . 20 Enable . 21 Clock Generator and Synchronization . 21 Soft-Start . 22 Bootstrap for High-side NMOS Drive 22 PWM Operation . 23 Current Sensing . 23 Adjustable Slope Compensation . 24 Light Load Efficiency Enhancement 25 Average Constant Current Control 25 Fault Monitoring and Protection . 26 Internal 5.2V LDO . 27 Application Information . 27 Output Voltage Setting . 27 Switching Frequency . 27 Output Inductor Selection . 28 Output Capacitor 28 Input Capacitor 28 Power MOSFET 29 Bootstrap Capacitor 29 Loop Compensation Design . 29 VCC Input Filter . 31 Current Sense Circuit . 31 Layout Consideration . 31 Revision History 32 About Intersil 32 Package Outline Drawing 33 FN8657 Rev 3.00 Page 2 of 34 December 12, 2014