DATASHEET
ISL65426
6A Dual Synchronous Buck Regulator with Integrated MOSFETs
The ISL65426 is a high efficiency dual output monolithic
synchronous buck converter operating over an input
voltage range of 3V to 5.5V. This single chip power solution
provides two output voltages, which are selectable or
externally adjustable from 1V to 80% of the supply voltage
while delivering up to 6A of total output current. The two
PWMs are synchronized 180
°
out-of-phase, reducing the
RMS input current and ripple voltage.
The ISL65426 switches at a fixed frequency of 1MHz and
utilizes current-mode control with integrated compensation
to minimize the size and number of external components
and provide excellent transient response. The internal
synchronous power switches are optimized for good
thermal performance and high efficiency.
A unique power block architecture allows partitioning of six
1A blocks to support one of four configuration options. One
master power block is associated with each synchronous
converter channel. Four floating slave power blocks allow
the user to assign them to either channel. Proper external
configuration of the power blocks is verified internally prior
to soft-start initialization.
Independent enable inputs allow for synchronization or
sequencing soft-start intervals of the two converter
channels. A third enable input allows additional sequencing
for multi-input bias supply designs. Individual power-good
indicators (PG1, PG2) signal when output voltage is within
the regulation window.
The ISL65426 integrates protection for both synchronous
buck regulator channels. The fault conditions include
overcurrent, undervoltage, and IC thermal monitor.
High integration contained in a thin Quad Flat No-lead
(QFN) package makes the ISL65426 an ideal choice to
power many of today’s small form factor applications. A
single chip solution for large scale digital ICs, like field
programmable gate arrays (FPGA), requiring separate core
and I/O voltages.
FN6340
Rev 3.00
March 25, 2008
Features
• High Efficiency: Up to 95%
• Fixed Frequency: 1MHz
• Operates From 3V to 5.5V Supply
• ±1% Reference
• Flexible Output Voltage Options
- Programmable 2-Bit VID Input
- Adjustable Output From 1V to 4.0V
• User-Partitioned Power Blocks
• Ultra-Compact DC/DC Converter Design
• PWMs Synchronized 180
°
Out-of-Phase
• Independent Enable Inputs and System Enable
• Stable All Ceramic Solutions
• Excellent Dynamic Response
• Independent Output Digital Soft-Start
• Power-Good Output Voltage Monitor
• Thermal-Overload Protection
• Overcurrent and Undervoltage Protection
• Pb-Free (RoHS Compliant)
Applications
• FPGA, CPLD, DSP, and CPU Core and I/O Voltages
- Xilinx Spartan III
TM
, Virtex II
TM
,
Virtex II Pro
TM
,
Virtex 4
TM
- Altera Stratix
TM
,
Stratix II
TM
,
Cyclone
TM
,
Cyclone II
TM
- Actel Fusion
TM
,
LatticeSC
TM
, LatticeEC
TM
• Low-Voltage, High-Density Distributed Power Systems
• Point-of-Load Regulation
• Distributed Power Systems
• Set-Top Boxes
Ordering Information
PART
NUMBER
(Note)
PART
MARKING
TEMP.
RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL65426HRZ* ISL65426 HRZ -10 to +100 50 Ld 5x10 QFN L50.5x10
ISL65426IRZA* ISL65426 IRZ
-40 to +85 50 Ld 5x10 QFN L50.5x10
*Add “-T” suffix for tape and reel. Please refer to TB347 for details on
reel specifications.
NOTE: These Intersil Pb-free plastic packaged products employ
special Pb-free material sets; molding compounds/die attach materials
and 100% matte tin plate PLUS ANNEAL - e3 termination finish, which
is RoHS compliant and compatible with both SnPb and Pb-free
soldering operations. Intersil Pb-free products are MSL classified at Pb-
free peak reflow temperatures that meet or exceed the Pb-free
requirements of IPC/JEDEC J STD-020.
FN6340 Rev 3.00
March 25, 2008
Page 1 of 22
ISL65426
Pinout
ISL65426
(50 LD QFN)
TOP VIEW
ISET2
PG1
PG2
PGND
EN1
EN2
FB1
FB2
42 PGND
41 PGND
40 PGND
39 PGND
38 LX6
37 LX6
36 PVIN6
35 PVIN5
PGND
34 LX5
33 PGND
32 PGND
31 LX4
30 PVIN4
29 PGND
28 PGND
27 GND
26 GND
18 19 20 21 22 23 24 25
PGND
ISET1
V1SET1
V1SET2
V2SET1
V2SET2
PGND
EN
50 49 48 47 46 45 44 43
PGND 1
PGND 2
PGND 3
PGND
4
LX1 5
LX1 6
PVIN1 7
PVIN2 8
LX2 9
PGND 10
PGND 11
LX3 12
PVIN3 13
VCC 14
VCC 15
VCC 16
PGND 17
FN6340 Rev 3.00
March 25, 2008
Page 2 of 22
ISL65426
Typical Application Schematics
SINGLE INPUT SUPPLY
3.3V
PG1
EN1
EN2
EN
3.3V
PVIN1
3.3V
C1
PVIN2
PG2
PVIN6
3.3V
PVIN5
PVIN4
C4
PVIN3
LX1
L1
1.2V
3A
LX2
C2
LX3
FB1
LX6
L2
LX5
2.5V
3A
ISL65426
LX4
FB2
C3
VCC
3.3V
C5
GND
PGND
ISET1
V1SET1
ISET2
V1SET2
V2SET2
V2SET1
3.3V
FIGURE 1. TYPICAL APPLICATION FOR 3A:3A CONFIGURATION
FN6340 Rev 3.00
March 25, 2008
Page 3 of 22
ISL65426
Typical Application Schematics
(Continued)
DUAL INPUT SUPPLY
3.3V
PG1
EN1
EN2
EN
5.0V
PVIN1
PVIN2
5.0V
C1
PVIN3
PVIN4
PG2
PVIN6
3.3V
PVIN5
C4
LX6
LX5
L2
1.8V
2A
C3
ISL65426
LX1
L1
1.5V
4A
C2
LX2
LX3
LX4
VCC
C5
GND
FB2
5.0V
FB1
PGND
V1SET2
V2SET1
V1SET1
V2SET2
ISET1
ISET2
3.3V
FIGURE 2. TYPICAL APPLICATION FOR 4A:2A CONFIGURATION
FN6340 Rev 3.00
March 25, 2008
Page 4 of 22
ISL65426
Typical Application Schematics
(Continued)
5.0V
PG1
EN1
EN2
EN
5.0V
PVIN1
PVIN2
5.0V
C2
C1
PVIN3
PVIN4
PVIN6
PVIN5
C4
5.0V
PG2
LX5
LX1
LX2
L1
C2
2.5V
5A
LX3
LX4
LX6
VCC
FB2
L2
C3
3.3V
1A
ISL65426
5.0V
C5
FB1
GND
PGND
ISET2
ISET1
V1SET1
V2SET1
V2SET2
V1SET2
5.0V
FIGURE 3. TYPICAL APPLICATION FOR 5A:1A CONFIGURATION
FN6340 Rev 3.00
March 25, 2008
Page 5 of 22
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