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ISL6308A
®
Data Sheet
September 9, 2008
FN6669.0
Three-Phase Buck PWM Controller with
High Current Integrated MOSFET Drivers
The ISL6308A is a three-phase PWM control IC with
integrated MOSFET drivers. It provides a precision voltage
regulation system for multiple applications including, but not
limited to, high current low voltage point-of-load converters,
embedded applications and other general purpose low
voltage medium to high current applications.The integration
of power MOSFET drivers into the controller IC marks a
departure from the separate PWM controller and driver
configuration of previous multi-phase product families. By
reducing the number of external parts, this integration allows
for a cost and space saving power management solution.
Output voltage can be programmed using the on-chip DAC
or an external precision reference. A two bit code programs
the DAC reference to one of 4 possible values (0.6V,
0.9V,1.2V and 1.5V). A unity gain, differential amplifier is
provided for remote voltage sensing, compensating for any
potential difference between remote and local grounds. The
output voltage can also be offset through the use of single
external resistor. An optional droop function is also
implemented and can be disabled for applications having
less stringent output voltage variation requirements or
experiencing less severe step loads.
A unique feature of the ISL6308A is the combined use of
both DCR and rDS(ON) current sensing. Load line voltage
positioning and overcurrent protection are accomplished
through continuous inductor DCR current sensing, while
rDS(ON) current sensing is used for accurate channel-current
balance. Using both methods of current sampling utilizes the
best advantages of each technique.
Protection features of this controller IC include a set of
sophisticated overvoltage and overcurrent protection.
Overvoltage results in the converter turning the lower
MOSFETs ON to clamp the rising output voltage and protect
the load. An OVP output is also provided to drive an optional
crowbar device. The overcurrent protection level is set
through a single external resistor. Other protection features
include protection against an open circuit on the remote
sensing inputs. Combined, these features provide advanced
protection for the output load.
Features
• Integrated Multi-Phase Power Conversion
- 1-, 2-, or 3-Phase Operation
• Precision Output Voltage Regulation
- Differential Remote Voltage Sensing
- ±0.8% System Accuracy Over-Temperature
(for REF=0.6V and 0.9V)
- ±0.5% System Accuracy Over-Temperature
(for REF=1.2V and 1.5V)
- Usable for Output Voltages not Exceeding 2.3V
- Adjustable Reference-Voltage Offset
• Precision Channel Current Sharing
- Uses Loss-Less rDS(ON) Current Sampling
• Optional Load Line (Droop) Programming
- Uses Loss-Less Inductor DCR Current Sampling
• Variable Gate-Drive Bias - 5V to 12V
• Internal or External Reference Voltage Setting
- On-Chip Adjustable Fixed DAC Reference Voltage with
2-bit Logic Input Selects from Four Fixed Reference
Voltages (0.6V, 0.9V, 1.2V, 1.5V)
- Reference can be Changed Dynamically
- Can use an External Voltage Reference
• Overcurrent Protection
• Multi-tiered Overvoltage Protection
- OVP Pin to Drive Optional Crowbar Device
• Selectable Operation Frequency up to 1.5MHz per Phase
• Digital Soft-Start
• Capable of Start-up in a Pre-Biased Load
• Pb-Free (RoHS Compliant)
Applications
• High Current DDR/Chipset Core Voltage Regulators
• High Current, Low Voltage DC/DC Converters
• High Current, Low Voltage FPGA/ASIC DC/DC Converters
Ordering Information
PART
NUMBER
PART
MARKING
TEMP. RANGE
(°C)
PACKAGE
PKG.
DWG. #
ISL6308ACRZ* (Note)
ISL6308AIRZ* (Note)
6308A CRZ
6308A IRZ
0 to +70
-40 to +85
40 Ld 6x6 QFN (Pb-free)
40 Ld 6x6 QFN (Pb-free)
L40.6x6
L40.6x6
ISL6308AEVAL1Z
Evaluation Platform
*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.
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. 2008. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.

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Pinout
ISL6308A
ISL6308A
(40 LD 6x6 QFN)
TOP VIEW
40 39 38 37 36 35 34 33 32 31
3PH 1
2PH 2
DAC 3
REF 4
OFST 5
VCC 6
COMP 7
FB 8
VDIFF 9
RGND 10
41
GND
30 BOOT1
29 PHASE1
28 PHASE2
27 UGATE2
26 BOOT2
25 ISEN2
24 PVCC2
23 LGATE2
22 PHASE3
21 BOOT3
11 12 13 14 15 16 17 18 19 20
2 FN6669.0
September 9, 2008

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Block Diagram
ICOMP DROOP OCSET
ISL6308A
PGOOD OVP
ENLL
ISUM
IREF
ISEN AMP
RGND
VSEN
VDIFF
x1
x1
UVP
OVP
OVP
REF1
REF0
DAC
+150mV
x 0.82
DAC
100µA
OC
+1V
SOFT-START
AND
FAULT LOGIC
0.2V
CLOCK AND
SAWTOOTH
GENERATOR
PWM1
PWM2
PWM3
0.66V
POWER-ON
RESET
GATE
SHOOT-
CONTROL THROUGH
LOGIC PROTECTION
GATE
SHOOT-
CONTROL THROUGH
LOGIC PROTECTION
CHANNEL
DETECT
REF
FB
COMP
OFST
OFFSET
CHANNEL
1
E/A
CURRENT
N
BALANCE
CHANNEL
CURRENT
SENSE
ISEN1 ISEN2 ISEN3
GATE
SHOOT-
CONTROL THROUGH
LOGIC PROTECTION
GND
3
VCC
PVCC1
BOOT1
UGATE1
PHASE1
LGATE1
FS
PVCC2
BOOT2
UGATE2
PHASE2
LGATE2
2PH
3PH
PVCC3
BOOT3
UGATE3
PHASE3
LGATE3
FN6669.0
September 9, 2008

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Typical Application - ISL6308A
ISL6308A
+5V
+12V
VDIFF
FB
VSEN
RGND
3PH
2PH
VCC
COMP
PVCC1
BOOT1
UGATE1
PHASE1
ISEN1
LGATE1
OFST
FS
PVCC2
DAC
REF
ISL6308A
BOOT2
UGATE2
PHASE2
ISEN2
REF1
REF0
OVP
PGOOD
LGATE2
PVCC3
GND
BOOT3
UGATE3
ENLL
IREF
DROOP
OCSET
ICOMP
PHASE3
ISEN3
ISUM
LGATE3
+12V
+12V
+12V
4
LOAD
FN6669.0
September 9, 2008

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ISL6308A
Absolute Maximum Ratings
Supply Voltage, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6V
Supply Voltage, PVCC . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +15V
Absolute Boot Voltage, VBOOT . . . . . . . . GND - 0.3V to GND + 36V
Phase Voltage, VPHASE . . . . . . . . GND - 0.3V to 15V (PVCC = 12)
GND - 8V (<400ns, 20µJ) to 24V (<200ns, VBOOT-PHASE = 12V)
Upper Gate Voltage, VUGATE . . . . VPHASE - 0.3V to VBOOT + 0.3V
VPHASE - 3.5V (<100ns Pulse Width, 2µJ) to VBOOT + 0.3V
Lower Gate Voltage, VLGATE. . . . . . . . GND - 0.3V to PVCC + 0.3V
GND - 5V (<100ns Pulse Width, 2µJ) to PVCC+ 0.3V
Input, Output, or I/O Voltage . . . . . . . . . GND - 0.3V to VCC + 0.3V
Thermal Information
Thermal Resistance
θJA (°C/W) θJC (°C/W)
QFN Package (Notes 1, 2) . . . . . . . . . .
32
3.5
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
Recommended Operating Conditions
VCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +5V ±5%
PVCC Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . +5V to 12V ±5%
Ambient Temperature (ISL6308ACRZ) . . . . . . . . . . . . 0°C to +70°C
Ambient Temperature (ISL6308AIRZ) . . . . . . . . . . . .-40°C to +85°C
CAUTION: Stress 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 section of this specification is not implied.
NOTES:
1. θJA 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.
2. For θJC, the “case temp” location is the center of the exposed metal pad on the package underside.
Electrical Specifications
Recommended Operating Conditions, Unless Otherwise Specified. Parameters with MIN and/or MAX limits are
100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and are
not production tested.
PARAMETER
TEST CONDITIONS
MIN TYP MAX UNITS
BIAS SUPPLY AND INTERNAL OSCILLATOR
Input Bias Supply Current
Gate Drive Bias Current
VCC POR (Power-On Reset) Threshold
IVCC; ENLL = high
IPVCC; ENLL = high; all gate outputs open,
Fsw = 250kHz
VCC Rising
12
0.4
4.25
15
0.8
4.38
18 mA
1.2 mA
4.47 V
VCC Falling
3.75 3.88 4.00 V
PVCC POR (Power-On Reset) Threshold
PVCC Rising
4.25 4.38 4.47 V
PVCC Falling
3.75 3.88 4.00 V
Oscillator Frequency
Fsw
225 250 275 kHz
Oscillator Ramp Amplitude (Note 3)
Maximum Duty Cycle (Note 3)
VP-P
- 1.50 - V
- 66.6 - %
CONTROL THRESHOLDS
ENLL Rising Threshold
0.595 0.630 0.670 V
ENLL Hysteresis
28 35 43 mV
ENLL Pull-Up current
ENLL = 1V
-0.5 -1.4 -3.0 µA
COMP Shutdown Threshold
COMP Falling
0.1 0.25 0.4 V
REFERENCE AND DAC
System Accuracy (DAC = 0.6V, 0.9V)
DROOP connected to IREF
-0.8 -
0.8 %
System Accuracy (DAC = 1.2V, 1.50V)
DROOP connected to IREF
-0.5 -
0.5 %
DAC Input Low Voltage (REF0, REF1)
- - 0.4 V
DAC Input High Voltage (REF0, REF1)
0.8 -
-V
Minimum External Reference (Note 4)
REF pin input
- 0.6 - V
5 FN6669.0
September 9, 2008