ISL6431 Datasheet, PDF (1/10 Pages) Intersil Corporation – Advanced Pulse-Width Modulation (PWM) Controller for Home Gateways

TM
Data Sheet
ISL6431
June 2001
File Number 9018
Advanced Pulse-Width Modulation (PWM)
Controller for Home Gateways
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-channel MOSFETs
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/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 r_DS(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.
Ordering Information
TEMP. RANGE
PART NUMBER
(^oC)
PACKAGE
ISL6431CB
0 to 70 8 Ld SOIC
ISL6431IB
-40 to 85 8 Ld SOIC
ISL6431EVAL1
Evaluation Board
PKG.
NO.
M8.15
M8.15
Features
• Operates from +5V Input
• 0.8V to V_IN Output Range
- 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 r_DS(ON)
• Small Converter Size
- 300kHz Fixed Frequency Oscillator
- Internal Soft Start
- 8 Lead SOIC Package
• High Conversion Efficiency
• Synchronous/Standard Buck Configuration
Applications
• 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
BOOT 1
UGATE 2
GND 3
LGATE 4
8 PHASE
7 COMP/OCSET
6 FB
5 VCC
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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