DATASHEET
ISL6420
FN9151
Rev 5.00
Feb 13, 2008
Advanced Single Synchronous Buck Pulse-Width Modulation (PWM) Controller
The ISL6420 makes simple work out of implementing a
complete control and protection scheme for a highperformance DC/DC buck converter. Designed to drive
N-channel MOSFETs in a synchronous rectified buck
topology, the ISL6420 integrates control, output adjustment,
monitoring and protection functions into a single package.
Additionally, the IC features an external reference voltage
tracking mode for externally referenced buck converter
applications and DDR termination supplies, as well as a
voltage margining mode for system testing in networking
DC/DC converter applications.
Features
The ISL6420 provides simple, single feedback loop, voltage
mode control with fast transient response. The output
voltage of the converter can be precisely regulated to as low
as 0.6V.
• Lossless, Programmable Overcurrent Protection
- Uses Upper MOSFET‘s rDS(ON)
The operating frequency is fully adjustable from 100kHz to
1.4MHz. High frequency operation offers cost and space
savings.
The error amplifier features a 15MHz gain-bandwidth
product and 6V/µs slew rate that enables high converter
bandwidth for fast transient response. The PWM duty cycle
ranges from 0% to 100% in transient conditions. Selecting
the capacitor value from the ENSS pin to ground sets a fully
adjustable PWM soft-start. Pulling the ENSS pin LOW
disables the controller.
The ISL6420 monitors the output voltage and generates a
PGOOD (power good) signal when soft-start sequence is
complete and the output is within regulation. A built-in
overvoltage protection circuit prevents the output voltage
from going above typically 115% of the set point. Protection
from overcurrent conditions is provided by monitoring the
rDS(ON) of the upper MOSFET to inhibit the PWM operation
appropriately. This approach simplifies the implementation
and improves efficiency by eliminating the need for a current
sensing resistor.
• Operates from 4.5V to 16V Input
• 0.6V Internal Reference Voltage
- ±1.0% Reference Voltage Accuracy
• Resistor-Selectable Switching Frequency
- 100kHz to 1.4MHz
• Voltage Margining and External Reference Tracking
Modes
• Output Can Sink or Source Current
• Programmable Soft-Start
• 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
• Extensive Circuit Protection Functions
- PGOOD, overvoltage, overcurrent, Shutdown
• QFN (4x4) Package
- 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
• Also Available in QSOP Package
• Pb-Free Available (RoHS Compliant)
Applications
• Power Supplies for Microprocessors/ASICs
- Embedded Controllers
- DSP and Core Processors
- DDR SDRAM Bus Termination
• Ethernet Routers and Switchers
• High-Power DC/DC Regulators
• Distributed DC/DC Power Architecture
• Personal Computer Peripherals
• Externally Referenced Buck Converters
FN9151 Rev 5.00
Feb 13, 2008
Page 1 of 20
ISL6420
Pinouts
ISL6420
(20 LD QSOP)
TOP VIEW
19
PVCC
PHASE
18
17
LGATE
20
UGATE
BOOT
ISL6420
(20 LD QFN)
TOP VIEW
CDEL
1
PGND
2
19 ENSS
16
LGATE
3
18 COMP
GPIO2
1
15 PGND
GPIO1/REFIN
2
14 CDEL
12 ENSS
VMSET/MODE
5
11 COMP
6
7
8
9
10
FB
4
RT
REFOUT
SGND
13 PGOOD
VIN
3
VCC5
OCSET
20 PGOOD
PVCC
4
17 FB
PHASE
5
16 RT
UGATE
6
15 SGND
BOOT
7
14 VIN
GPIO2
8
13 VCC5
GPIO1/REFIN
9
12 VMSET/MODE
OCSET 10
11 REFOUT
Ordering Information
PART NUMBER
PART MARKING
TEMP.
RANGE (°C)
-40 to +85
PACKAGE
20 Ld 4x4 QFN
PKG.
DWG. #
ISL6420IR
ISL 6420IRZ
ISL6420IR-T*
ISL 6420IRZ
ISL6420IRZ (Note)
64 20IRZ
ISL6420IRZ-T* (Note)
64 20IRZ
20 Ld 4x4 QFN Tape and Reel (Pb-free)
L20.4x4
ISL6420IRZ-TK* (Note)
64 20IRZ
20 Ld 4x4 QFN Tape and Reel (Pb-free)
L20.4x4
ISL6420IA
ISL 6420IA
-40 to +85
ISL6420IA-TK*
ISL 6420IA
20 Ld QSOP Tape and Reel
ISL6420IAZ (Note)
ISL 6420IAZ
ISL6420IAZ-TK* (Note)
ISL 6420IAZ
20 Ld 4x4 QFN Tape and Reel
-40 to +85
-40 to +85
20 Ld 4x4 QFN (Pb-free)
20 Ld QSOP
L20.4x4
L20.4x4
L20.4x4
M20.15
M20.15
20 Ld QSOP (Pb-free)
20 Ld QSOP Tape and Reel (Pb-free)
M20.15
M20.15
*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.
FN9151 Rev 5.00
Feb 13, 2008
Page 2 of 20
ISL6420
Functional Block Diagram
VIN
VCC5
OCSET
SGND
LDO
OVERCURRENT
COMP
+
OCFLT
PHASE
REFERENCE
0.6V
SS
+
OVFLT
UVFLT
UGATE
FAULT
LOGIC
PHASE
ERROR
AMP
-
FB
BOOT
+
-
COMP
PHASE
LOGIC
PWM
LOGIC
PWM
COMP
PVCC
GPIO1/REFIN
LGATE
RAMP
GENERATOR
GPIO2
REFOUT
VOLTAGE
MARGINING
VMSET/MODE
OV/UV
VOLTAGE
MONITOR
FB
PGND
OVFLT
UVFLT
OSC
EN/SS
RT
ENSS
PGOOD
CDEL
Typical 5V Input DC/DC Application Schematic
5V
C6
C1
C3
C2
PVCC
VIN
VCC5
D1
OCSET
MONITOR AND
PROTECTION
ENSS
Q1
PGOOD
C8
C9
UGATE
OSC
R2
CDEL
R1
BOOT
RT
C7
0.1µF
C5
C4
L1
PHASE
REF
3.3V
SGND
++
--
FB
R3
C11
COMP
Q2
C10
PGND
GPIO1/REFIN
R6
R5
LGATE
-+
+
C12
REFOUT
GPIO2
C13
R4
FN9151 Rev 5.00
Feb 13, 2008
VMSET/MODE
Page 3 of 20
ISL6420
Typical 12V Input DC/DC Application Schematic
12V
C6
C1
C3
C2
PVCC
VIN
VCC5
D1
OCSET
MONITOR AND
PROTECTION
ENSS
Q1
PGOOD
R2
C9
UGATE
OSC
L1
PHASE
CDEL
C8
R1
BOOT
RT
C7
C5
C4
REF
3.3V
SGND
R3
C11
C10
PGND
COMP
GPIO1/REFIN
R6
C12
R5
Q2
LGATE
-+
+
++
--
FB
REFOUT
GPIO2
C13
R4
VMSET/MODE
Typical 5V Input DC/DC Application Schematic
5V
C6
C1
C3
C2
VIN
PVCC
C4
D1
VCC5
OCSET
MONITOR AND
PROTECTION
SS/EN
Q1
CDEL
R2
R1
BOOT
RT
C7
C5
C8
UGATE
OSC
L1
PHASE
PGOOD
REF
2.5V/1.25V
SGND
R3
C10
C11
LGATE
-+
+
++
--
FB
COMP
R5
C9
GPIO1/REFIN
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