6439CBZ

® ISL6439, ISL6439A Data Sheet November 5, 2008 FN9057.5 Single Sync Buck PWM Controller for Broadband Gateway Applications The ISL6439 makes easy work out of implementing a complete control and protection scheme for a DC/DC step-down converter. Designed to drive N-Channel MOSFETs in a synchronous buck topology, the ISL6439 integrates the control, output adjustment, monitoring and protection functions into a single package. The ISL6439 provides simple, single feedback loop, voltagemode control with fast transient response. The output voltage can be precisely regulated to as low as 0.8V, with a maximum tolerance of ±1.5% over temperature and line voltage variations. A fixed frequency oscillator reduces design complexity, while balancing typical application cost and efficiency. The error amplifier features a 15MHz gain-bandwidth product and 6V/μs slew rate which enables high converter bandwidth for fast transient performance. The resulting PWM duty cycles range from 0% to 100%. Protection from overcurrent conditions is provided by monitoring the rDS(ON) of the upper MOSFET to inhibit PWM operation appropriately. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sense resistor. Features Operates from 3.3V to 5V Input 0.8V to VIN Output Range - 0.8V Internal Reference - ±1.5% Over Load, Line Voltage and Temperature Drives N-Channel MOSFETs Simple Single-Loop Control Design - Voltage-Mode PWM Control Fast Transie...