®
ISL6406, ISL6426
Data Sheet
November 1, 2004
FN9073.6
Single Synchronous Buck Pulse-Width
Modulation (PWM) Controller
The ISL6406, ISL6426 is an adjustable frequency,
synchronous buck switching regulator optimized for
generating lower voltages for the distributed DC-DC
architectures. The ISL6406 offers an adjustable output
voltage, while the ISL6426 provides a fixed 1.8V output.
Designed to drive N-Channel MOSFETs in synchronous
buck topology, the ISL6406, ISL6426 integrates the control,
output adjustment and protection functions into a single
package.
The ISL6406, ISL6426 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.
The error amplifier features a 15MHz gain-bandwidth
product and 6V/µs slew rate which enables high converter
bandwidth for fast transient performance.
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.
The wide programmable switching frequency range of
100kHz to 700kHz allows the use of small surface mount
inductors and capacitors. The device also provides external
frequency synchronization making it an ideal choice for
DC-DC converter applications.
Features
• Operates from 3.3V/5V Input
• 0.8V to V
IN
Output Range
- 0.8V Internal Reference
- ±1.5% Reference Accuracy
• Simple Single-Loop Control Design
- Voltage-Mode PWM Control
• Fast Transient Response
- High-Bandwidth Error Amplifier
• Lossless, Programmable Overcurrent Protection
- Uses Upper MOSFET’s r
DS(on)
• Programmable Switching Frequency 100kHz–700kHz
• External Frequency Synchronization
• Two Device Options Available
- ISL6406 . . . . . . . . . . . . . . . . Adjustable Output Voltage
- ISL6426 . . . . . . . . . . . . . . . . . . . . . . Fixed 1.8V Output
• Internal Soft-Start
• QFN Package Option
- QFN Compliant to JEDEC PUB95 MO-220 QFN - Quad
Flat No Leads - Product Outline
- QFN Near Chip Scale Package Footprint; Improves
PCB Efficiency, Thinner in Profile
• Pb-Free Packaging Available (RoHS Compliant)
- Designated with “Z” Suffix (Refer to Note)
Applications
• 3V/5V DC-DC Converter Modules
• Distributed DC-DC 3.3V, 2.5V and 1.8V Power
Architectures for DSP, Logic, and Memory
• Power Supplies for Microprocessors
- PCs
- Embedded Controllers
• Memory Supplies
• Personal Computer Peripherals
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2003-2004. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6406, ISL6426
Absolute Maximum Ratings
Supply Voltage, VCC (Note 1) . . . . . . . . . . . . . . . . . . . . . . . . . +7.0V
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
Thermal Information
Thermal Resistance (Typical)
θ
JA
(°C/W)
θ
JC
(°C/W)
SOIC (Note 2) . . . . . . . . . . . . . . . . . . .
70
N/A
TSSOP (Note 2) . . . . . . . . . . . . . . . . . .
90
N/A
QFN (Notes 3, 4) . . . . . . . . . . . . . . . . .
35
4.5
Maximum Junction Temperature (Plastic Package) . . -55°C to 150°C
Maximum Storage Temperature Range . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300°C
(SOIC - Lead Tips Only)
Operating Conditions
Temperature Range
ISL6406, ISL6426C . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
ISL6406, ISL6426I . . . . . . . . . . . . . . . . . . . . . . . . . .-40°C to 85°C
Supply Voltage Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.3V ±10%
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTES:
1. Please refer to the Typical Application Schematics (page 3) for 3.3V / 5V input configuration.
2.
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.
3.
θ
JA
is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See
Tech Brief TB379.
4. For
θ
JC
, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
PARAMETER
V
CC
SUPPLY
Shutdown Supply Current
Operating Supply Current (Note 5)
REFERENCE VOLTAGE
Nominal Reference Voltage
Reference Voltage Tolerance
Recommended operating conditions unless otherwise noted. Refer to Block Diagram and Typical Application
Schematic. V
CC
= +3.3V. Typical values are at T
A
= 25°C.
TEST CONDITIONS
MIN
TYP
MAX
UNITS
SYNC/EN = GND
RT = 64.9kΩ
-
7
20
9.8
50
11.5
µA
mA
-
-1.5
T
A
= 0°C to 70°C
T
A
= -40°C to +85°C
-1.8
-2.1
0.8
-
-
-
-
1.5
1.8
2.1
V
%
%
%
ERROR AMPLIFIER
Open Loop Voltage Gain (Note 6)
Gain-Bandwidth Product (Note 6)
Slew Rate (Note 5)
CHARGE PUMP
Nominal Charge Pump Output
Charge Pump Output Regulation
POWER-ON RESET
Rising CPVOUT POR Threshold
T
A
= 0°C to 70°C
T
A
= -40°C to +85°C
CPVOUT POR Threshold Hysteresis
OSCILLATOR
Gate Output Frequency Range
RT = 200kΩ
RT = 64.9kΩ
RT = 26.1kΩ
Sawtooth Amplitude
Peak-to-Peak
∆V
OSC
80
250
650
1.1
100
300
715
1.4
120
340
770
1.7
kHz
kHz
kHz
V
4.20
4.1
0.3
4.35
4.35
0.5
4.5
4.6
0.9
V
V
V
V
CC
= 3.3V, No Load
4.8
-5.0
5.1
-
5.5
5.0
V
%
COMP = 10pF
-
14
4.65
82
-
6.0
-
-
9.2
dB
MHz
V/µs
5
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