1
FN9057.6
ISL6439, ISL6439A
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, 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
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.
Features
• Operates from 3.3V to 5V Input
• 0.8V to V
IN
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 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
- Internal Fixed Frequency Oscillator
- ISL6439: 300kHz
- ISL6439A: 600kHz
• Internal Soft-Start
• 14 Pin SOIC or 16 Lead 5x5 QFN
• QFN Package:
- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat
No Lead - Package Outline
- Near Chip Scale Package footprint, which improves
PCB efficiency and has a thinner profile
• Pb-free (RoHS compliant)
Applications
• Cable Modems, Set Top Boxes, and DSL Modems
• DSP and Core Communications Processor Supplies
• Memory Supplies
• Personal Computer Peripherals
• Industrial Power Supplies
• 3.3V-Input DC/DC Regulators
• Low-Voltage Distributed Power Supplies
Data Sheet September 15, 2015
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
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