ISL6431A

Features:

* Operates from +5V Input
* 0.8V to V  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
   - High-Bandwidth Error Amplifier
   - Full 0% to 100% Duty Cycle
* Lossless, Programmable Overcurrent Protection
   - Uses Upper MOSFET's r DS(on)
* Converter Can Source and Sink Current
* Small Converter Size
   - 300kHz Fixed Frequency Oscillator
   - Internal Soft Start
   - 8-Lead SOIC Package


Application

* Cable/DSL Routers and DSL Modems
* DSP and Core Communications Processor Supplies
* Broadband Gateways
* Memory Supplies
* 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
ESD Classification. . . . . . . . . . . . . . . . . . . . . .. . .Class 2


Description

The ISL6431A is a high efficiency, fixed frequency,  synchronous buck PWM controller. It is designed for use in  applications that convert 5V to lowerdistributed voltages  required for DSL modems, cable and DSL routers and  broadband gateway core processor, memory and peripheral  power supplies.

The ISL6431A makes simple work out of implementing a  complete control and protection scheme for a DC-DC  stepdown converter. Designed to drive N channel MOSFETs  in a synchronous buck topology, the ISL6431A integrates  the control, output adjustment, monitoring and protection  functions into a single 8-Lead package.

The ISL6431A 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. The device is capable of sinking, as  well as sourcing current. A fixed frequency oscillator reduces  design complexity, while balancing typical application cost  and efficiency.

The error amplifier ISL6431A  features a 15MHz gain-bandwidth  product and 8V/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  monitoring the r  of the upper MOSFET to inhibit PWM  DS(ON) operation appropriately. This approach simplifies the  implementation and improves efficiency by eliminating the  need for a current sense resistor.