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®
Data Sheet
October 2003
ISL6552
FN4918.1
Microprocessor CORE Voltage Regulator
Multi-Phase Buck PWM Controller
The ISL6552 multi-phase PWM control IC together with its
companion gate drivers, the HIP6601, HIP6602 or HIP6603
and external Intersil MOSFETs provides a precision voltage
regulation system for advanced microprocessors.
Multi-phase power conversion is a marked departure from
earlier single phase converter configurations previously
employed to satisfy the ever increasing current demands of
modern microprocessors. Multi-phase converters, by
distributing the power and load current results in smaller and
lower cost transistors with fewer input and output capacitors.
These reductions accrue from the higher effective
conversion frequency with higher frequency ripple current
due to the phase interleaving process of this topology. For
example, a three phase converter operating at 350kHz will
have a ripple frequency of 1.05MHz. Moreover, greater
converter bandwidth of this design results in faster response
to load transients.
Outstanding features of this controller IC include
programmable VID codes from the microprocessor that
range from 1.05V to 1.825V with a system accuracy of ±1%.
Pull up currents on these VID pins eliminates the need for
external pull up resistors. In addition “droop” compensation,
used to reduce the overshoot or undershoot of the CORE
voltage, is easily programmed with a single resistor.
Another feature of this controller IC is the PGOOD monitor
circuit which is held low until the CORE voltage increases,
during its Soft-Start sequence, to within 10% of the
programmed voltage. Over-voltage, 15% above
programmed CORE voltage, results in the converter shutting
down and turning the lower MOSFETs ON to clamp and
protect the microprocessor. Under voltage is also detected
and results in PGOOD low if the CORE voltage falls 10%
below the programmed level. Over-current protection
reduces the regulator RMS output current to 41% of the
programmed over-current trip value. These features provide
monitoring and protection for the microprocessor and power
system.
Features
• Multi-Phase Power Conversion
• Precision Channel Current Sharing
- Loss Less Current Sampling - Uses rDS(ON)
• Precision CORE Voltage Regulation
- ±1% System Accuracy Over Temperature
• Microprocessor Voltage Identification Input
- 5-Bit VID Input
- 1.05V to 1.825V in 25mV Steps
- Programmable “Droop” Voltage
• Fast Transient Recovery Time
• Over Current Protection
• Automatic Selection of 2, 3, or 4 Phase Operation
• High Ripple Frequency (Channel Frequency) Times
Number Channels . . . . . . . . . . . . . . . . . .100kHz to 6MHz
• QFN Package:
- Compliant to JEDEC PUB95 MO-220
QFN - Quad Flat No Leads - Package Outline
- Near Chip Scale Package footprint, which improves
PCB efficiency and has a thinner profile
Ordering Information
PART NUMBER TEMP. (oC) PACKAGE PKG. DWG. #
ISL6552CB
0 to 70 20 Ld SOIC M20.3
ISL6552CB-T
20 Ld SOIC Tape and Reel
ISL6552CR
0 to 70 20 Ld 5x5 QFN L20.5x5
ISL6552CR-T
20 Ld QFN Tape and Reel
1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2003. All Rights Reserved.
All other trademarks mentioned are the property of their respective owners.

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Pinouts
ISL6552CB (20 LEAD SOIC
TOP VIEW
VID3 1
VID2 2
VID1 3
VID0 4
VID25mV 5
COMP 6
FB 7
FS/DIS 8
GND 9
VSEN 10
20 VCC
19 PGOOD
18 PWM4
17 ISEN4
16 ISEN1
15 PWM1
14 PWM2
13 ISEN2
12 ISEN3
11 PWM3
ISL6552
ISL6552CR (20 LEAD 5x5 QFN)
TOP VIEW
20 19 18 17 16
VID1 1
VID0 2
VID25mV 3
COMP 4
FB 5
GND
15 ISEN4
14 ISEN1
13 PWM1
12 PWM2
11 ISEN2
6 7 8 9 10
2

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Block Diagram
ISL6552
PGOOD
VCC
VSEN
COMP
VID3
VID2
VID1
VID0
VID25mV
FB
X 0.9
X1.15
+ UV
-
OVP
+
-
OV
LATCH
S
POWER-ON
RESET (POR)
CLOCK AND
SAWTOOTH
GENERATOR
THREE
STATE
+
-
PWM
+
-
SOFT-
START
AND FAULT
LOGIC
+
-
PWM
+
-
+
-
PWM
+
-
D/A
+ E/A
-
+
-
PWM
+
-
CURRENT
CORRECTION
I_TOT
+
+
-+
OC I_TRIP
+
+
PHASE
NUMBER CHANNEL
DETECTOR
GND
FS/EN
PWM1
PWM2
PWM3
PWM4
ISEN1
ISEN2
ISEN3
ISEN4
3

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Simplified Power System Diagram
ISL6552
VSEN
PWM 1
PWM 2
ISL6552
PWM 3
PWM 4
VID
SYNCHRONOUS
RECTIFIED BUCK
CHANNEL
SYNCHRONOUS
RECTIFIED BUCK
CHANNEL
SYNCHRONOUS
RECTIFIED BUCK
CHANNEL
SYNCHRONOUS
RECTIFIED BUCK
CHANNEL
MICROPROCESSOR
Functional Pin Description
ISL6552CB (20 LEAD SOIC)
VID3 1
VID2 2
VID1 3
VID0 4
VID25mV 5
COMP 6
FB 7
FS/DIS 8
GND 9
VSEN 10
20 VCC
19 PGOOD
18 PWM4
17 ISEN4
16 ISEN1
15 PWM1
14 PWM2
13 ISEN2
12 ISEN3
11 PWM3
ISL6552CR (20 LEAD 5x5 QFN)
20 19 18 17 16
VID1 1
VID0 2
VID25mV 3
COMP 4
FB 5
GND
15 ISEN4
14 ISEN1
13 PWM1
12 PWM2
11 ISEN2
6 7 8 9 10
4
VID3, VID2, VID1, VID0 and VID25mV
Voltage Identification inputs from microprocessor. These pins
respond to TTL and 3.3V logic signals. The ISL6552 decodes
VID bits to establish the output voltage. See Table 1.
COMP
Output of the internal error amplifier. Connect this pin to the
external feedback and compensation network.
FB
Inverting input of the internal error amplifier.
FS/DIS
Channel frequency, FSW, select and disable. A resistor from
this pin to ground sets the switching frequency of the
converter. Pulling this pin to ground disables the converter
and three states the PWM outputs. See Figure 10.
GND
Bias and reference ground. All signals are referenced to this
pin.
VSEN
Power good monitor input. Connect to the microprocessor-
CORE voltage.
PWM1, PWM2, PWM3 and PWM4
PWM outputs for each driven channel in use. Connect these
pins to the PWM input of a HIP6601, HIP6602, HIP6603
driver. For systems which use 3 channels, connect PWM4
high. Two channel systems connect PWM3 and PWM4 high.

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ISL6552
ISEN1, ISEN2, ISEN3 and ISEN4
Current sense inputs from the individual converter channel’s
phase nodes. Unused sense lines MUST be left open.
PGOOD
Power good. This pin provides a logic-high signal when the
microprocessor CORE voltage (VSEN pin) is within specified
limits and Soft-Start has timed out.
VCC
Bias supply. Connect this pin to a 5V supply.
Typical Application - 2 Phase Converter Using HIP6601 Gate Drivers
+5V
FB COMP
VSEN
VCC
PGOOD
VID3
PWM4
PWM3
PWM2
VID2
VID1
VID0
PWM1
MAIN
CONTROL
ISL6552
VID25mV
FS/DIS
GND
ISEN4
ISEN3
ISEN2
ISEN1
NC
NC
+12V
PVCC
VCC
BOOT
UGATE
PHASE
PWM
DRIVER
HIP6601
LGATE
GND
+12V
PVCC
BOOT
UGATE
VCC
PWM
DRIVER
HIP6601
PHASE
LGATE
GND
VIN = +5V
VIN = +5V
+VCORE
5