ISL6431

Features:

* Operates from +5V Input
* 0.8VtoV Output Range IN
   - 0.8V Internal Reference
   - ±1.5% Over Line Voltage and Temperature
* Drives N-Channel MOSFETs
* Simple Single-Loop Control Design
   - Voltage-Mode PWM Control
* Fast Transient Response
* Lossless, Programmable Overcurrent Protection
   - Uses Upper MOSFET's rDS(ON)
* Small Converter Size
   - 300kHz Fixed Frequency Oscillator
   - Internal Soft Start
   - 8 Lead SOIC Package
* High Conversion Efficiency
* Synchronous/Standard Buck Configuration


Application

* Cable Modems, Set Top Boxes, and DSL Modems
* DSP and Core Communications Processor Supplies
* Power Supplies for Microprocessors and Embedded Controllers
* Memory Supplies
* Personal Computer Peripherals
* Industrial Power Supplies
* 5V-Input DC-DC Regulators
* Low-Voltage Distributed Power Supplies


Pinout




Specifications

Supply Voltage, V_CC..................................................+6.0V
Absolute Boot Voltage, V_BOOT ................................+15.0V
Upper Driver Supply Voltage, V_BOOT -V_PHASE ............+6.0V
Input, Output or I/O Voltage. . . .  GND -0.3V to VCC +0.3V
ESDClassification......................................................Class2


Description

The ISL6431 is a high efficiency, fixed frequency, synchronous buck PWM controller. It is designed for use in applications that convert 5V to lower distributed voltages required for set-top box, cable modem, DSL modem and residential home gateway core processor, memory and peripheral power supplies.

This device makes simple work out of implementing a complete control and protection scheme for a DC-DC stepdown converter. Designed to drive N channelMOSFETs in a synchronous buck topology, the ISL6431 integrates the control, output adjustment, monitoring and protection functions into a single 8-pin package.

The ISL6431 provides simple, single feedback loop, voltage- mode 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/s 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 monitoringthe r ofthe upperMOSFET toinhibitPWM DS(ON) operation appropriately. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sense resistor.