®
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, 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.
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
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
|
Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2003-2004, 2008. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.
ISL6439, ISL6439A
Absolute Maximum Ratings
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .+7V
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
Thermal Information
Thermal Resistance
θ
JA
(°C/W)
θ
JC
(°C/W)
SOIC Package (Note 1) . . . . . . . . . . . .
67
N/A
QFN Package (Note 2). . . . . . . . . . . . .
35
5
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . +150°C
Maximum Storage Temperature Range . . . . . . . . . .-65°C to +150°C
Pb-Free Reflow Profile. . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
For Recommended soldering conditions see Tech Brief TB389.
Operating Conditions
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . +3.3V ±10%
Ambient Temperature Range . . . . . . . . . . . . . . . . . . .-40°C to +85°C
Junction Temperature Range. . . . . . . . . . . . . . . . . .-40°C to +125°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and
result in failures not covered by warranty.
NOTE:
1.
θ
JA
is measured with the component mounted on a high effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
2.
θ
JA
is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features.
θ
JC,
the
“case temp” is measured at the center of the exposed metal pad on the package underside. See Tech Brief TB379.
3. Limits established by characterization and are not production tested.
Electrical Specifications
PARAMETER
VCC SUPPLY CURRENT
Nominal Supply
POWER-ON RESET
Rising CPVOUT POR Threshold
Recommended Operating Conditions, Unless Otherwise Noted V
CC
= 3.3V±5% and T
A
= +25°C
SYMBOL
TEST CONDITIONS
MIN
TYP
MAX
UNITS
I
BIAS
6.1
6.9
7.7
mA
POR
Commercial
Industrial
4.25
4.10
0.3
4.30
4.30
0.6
4.42
4.50
0.9
V
V
V
CPVOUT POR Threshold Hysteresis
OSCILLATOR
Frequency
f
OSC
IC = ISL6439C, Commercial
IC = ISL6439I, Industrial
IC = ISL6439AC, Commercial
IC = ISL6439AI, Industrial
Ramp Amplitude
REFERENCE
Reference Voltage Tolerance
Nominal Reference Voltage
Charge Pump
Nominal Charge Pump Output
Charge Pump Output Regulation
ERROR AMPLIFIER
DC Gain
Gain-Bandwidth Product
Slew Rate
SOFT START
Soft Start Slew Rate
Commercial
Industrial
GBWP
SR
Note 3
V
CPVOUT
V
VCC
= 3.3V, No Load
V
REF
ΔV
OSC
275
250
554
524
-
300
300
600
600
1.5
325
340
645
650
-
kHz
kHz
kHz
kHz
V
P-P
-
-
-
0.800
1.5
-
%
V
-
-
5.1
2
-
-
V
%
-
-
-
88
15
6
-
-
-
dB
MHz
V/μs
6.2
6.2
7.3
7.6
ms
ms
5
FN9057.5
November 5, 2008
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