®
ISL6527, ISL6527A
Data Sheet
November 18, 2008
FN9056.10
Single Synchronous Buck Pulse-Width
Modulation (PWM) Controller
The ISL6527, ISL6527A make simple work out of
implementing a complete control and protection scheme for
a DC/DC step-down converter. Designed to drive N-Channel
MOSFETs in a synchronous buck topology, the ISL6527,
ISL6527A integrate the control, output adjustment,
monitoring and protection functions into a single package.
The ISL6527, ISL6527A provide simple, single feedback loop,
voltage-mode control with fast transient response. The output
voltage can be regulated to as low as the provided external
reference. A fixed frequency oscillator reduces design
complexity, while balancing typical application cost and
efficiency.
The error amplifier features a 15MHz gain-bandwidth
product and 6V/µs slew rate, which enables high converter
bandwidth for fast transient performance. The resulting
PWM duty cycles range from 0% to 100%.
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.
Features
• Operates from 3.3V to 5V Input
• Utilizes an External Reference
• 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
• Lossless, Programmable Overcurrent Protection
- Uses Upper MOSFET’s r
DS(ON)
• Converter Can Source and Sink Current
• Small Converter Size
- Internal Fixed Frequency Oscillator
- ISL6527: 300kHz
- ISL6527A: 600kHz
• Internal Soft-Start
• 14 Ld SOIC or 16 Ld 5x5 QFN
• 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
• Pb-Free (RoHS compliant)
Applications
• Power Supplies for Microprocessors
- PCs
- Embedded Controllers
• Subsystem Power Supplies
- PCI/AGP/GTL+ Busses
- ACPI Power Control
- DDR SDRAM Bus Termination Supply
• Cable Modems, Set-Top Boxes, and DSL Modems
• DSP and Core Communications Processor Supplies
• Memory Supplies
• Personal Computer Peripherals
• Industrial Power Supplies
• 3.3V Input DC/DC Regulators
• Low Voltage Distributed Power Supplies
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774
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Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright Intersil Americas Inc. 2003-2008. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
ISL6527, ISL6527A
Ordering Information
PART NUMBER
(Note)
ISL6527ACBZ*
ISL6527ACRZ*
ISL6527AIBZ*
ISL6527AIRZ*
ISL6527CBZ*
ISL6527CRZ*
ISL6527IBZ*
ISL6527IRZ*
ISL6527EVAL1
ISL6527EVAL2
ISL6527AEVAL1
ISL6527AEVAL2
PART MARKING
6527ACBZ
ISL6527 ACRZ
6527AIBZ
ISL6527 AIRZ
6527CBZ
ISL6527 CRZ
6527IBZ
ISL6527 IRZ
TEMP
RANGE (°C)
0 to +70
0 to +70
-40 to +85
-40 to +85
0 to +70
0 to +70
-40 to +85
-40 to +85
14 Ld SOIC
16 Ld 5x5 QFN
14 Ld SOIC
16 Ld 5x5 QFN
14 Ld SOIC
16 Ld 5x5 QFN
14 Ld SOIC
16 Ld 5x5 QFN
PACKAGE
(Pb-Free)
PKG
DWG. #
M14.15
L16.5x5B
M14.15
L16.5x5B
M14.15
L16.5x5B
M14.15
L16.5x5B
ISL6527 SOIC Evaluation Board
ISL6527 QFN Evaluation Board
ISL6527A SOIC Evaluation Board
ISL6527A QFN Evaluation Board
*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.
Pinouts
ISL6527, ISL6527A
(14 LD SOIC)
TOP VIEW
GND 1
LGATE 2
CPVOUT 3
CT1 4
CT2 5
OCSET/SD 6
FB 7
14 UGATE
13 BOOT
12 PHASE
11 VCC
10 CPGND
9 REF_IN
8 COMP
CPVOUT 1
CT1 2
CT2 3
OCSET/SD 4
5
NC
6
FB
7
COMP
8
REF_IN
ISL6527, ISL6527A
(16 LD QFN)
TOP VIEW
UGATE
14
LGATE
BOOT
13
12 PHASE
11 VCC
10 CPGND
9
NC
GND
15
16
2
FN9056.10
November 18, 2008
ISL6527, ISL6527A
Typical Application - 3.3V Input
3.3V
V
IN
C
IN
C
BULK
OCSET/SD
R
OCSET
C
PUMP
CT2
CPVOUT
VCC
CT1
ISL6527,
ISL6527A
BOOT
D
BOOT
C
DCPL
C
HF
CPGND
GND
UGATE
PHASE
V
REF
REF_IN
LGATE
COMP
FB
C
BOOT
Q
1
L
OUT
V
OUT
Q
2
C
OUT
C
I
R
FB
R
F
C
F
R
OFFSET
3
FN9056.10
November 18, 2008
ISL6527, ISL6527A
Typical Application - 5V Input
+5V
V
IN
VCC
CT1
OCSET/SD
R
OCSET
CPVOUT
N/C
CT2
C
BULK
ISL6527,
ISL6527A
BOOT
D
BOOT
C
IN
CHF
CPGND
GND
C
BOOT
UGATE
PHASE
Q
1
L
OUT
V
OUT
V
REF
REF_IN
LGATE
COMP
FB
Q
2
C
OUT
C
I
R
FB
R
F
C
F
R
OFFSET
Block Diagram
VCC
CPVOUT
CT1
CT2
CPGND
OCSET/SD
20μA
CHARGE
PUMP
POWER-ON
RESET (POR)
BOOT
OC
COMPARATOR
+
-
SOFT-START
UGATE
PHASE
ERROR
AMP
+
-
PWM
COMPARATOR
+
-
INHIBIT
REF_IN
GATE
CONTROL
LOGIC
PWM
LGATE
FB
OSCILLATOR
COMP
FIXED 300kHz or 600kHz
GND
4
FN9056.10
November 18, 2008
ISL6527, ISL6527A
Functional Pin Description
14 LD (SOIC)
TOP VIEW
GND 1
LGATE 2
CPVOUT 3
CT1 4
CT2 5
OCSET/SD 6
FB 7
14 UGATE
13 BOOT
12 PHASE
11 VCC
10 CPGND
9 REF_IN
8 COMP
UGATE
Connect this pin to the upper MOSFET’s gate. This pin
provides the PWM-controlled gate drive for the upper
MOSFET. This pin is also monitored by the adaptive
shoot-through protection circuitry to determine when the
upper MOSFET has turned off.
BOOT
This pin provides ground referenced bias voltage to the
upper MOSFET driver. A bootstrap circuit is used to create a
voltage suitable to drive a logic-level N-channel MOSFET.
LGATE
16 LD 5X5 (QFN)
TOP VIEW
UGATE
LGATE
BOOT
GND
Connect this pin to the lower MOSFET’s gate. This pin
provides the PWM-controlled gate drive for the lower
MOSFET. This pin is also monitored by the adaptive
shoot-through protection circuitry to determine when the
lower MOSFET has turned off.
16
CPVOUT 1
CT1 2
CT2 3
OCSET/SD 4
5
NC
15
14
13
12 PHASE
11 VCC
10 CPGND
9
NC
OCSET/SD
Connect a resistor (R
OCSET
) from this pin to the drain of the
upper MOSFET (V
IN
). R
OCSET
, an internal 20µA current
source (I
OCSET
), and the upper MOSFET ON-resistance
(r
DS(ON)
) set the converter overcurrent (OC) trip point
according to Equation 1:
I
OCSET
xR
OCSET
I
PEAK
= -------------------------------------------------
r
DS
(
ON
)
6
FB
7
COMP
8
REF_IN
(EQ. 1)
An overcurrent trip cycles the soft-start function.
Pulling OCSET/SD to a voltage level below 0.8V disables
the controller. Disabling the ISL6527, ISL6527A causes the
oscillator to stop, the LGATE and UGATE outputs to be held
low, and the soft-start circuitry to re-arm.
VCC
This pin provides the bias supply for the ISL6527, ISL6527A.
Connect a well-decoupled 3.3V supply to this pin.
COMP and FB
COMP and FB are two of the three available external pins of
the error amplifier. The FB pin is the inverting input of the
internal error amplifier and the COMP pin is the error
amplifier output. These pins are used to compensate the
voltage-control feedback loop of the converter.
CT1 and CT2
These pins are the connections for the external charge
pump capacitor. A minimum of a 0.1µF ceramic capacitor is
recommended for proper operation of the IC.
CPVOUT
This pin represents the output of the charge pump. The
voltage at this pin is the bias voltage for the IC. Connect a
decoupling capacitor from this pin to ground. The value of
the decoupling capacitor should be at least 10x the value of
the charge pump capacitor. This pin may be tied to the
bootstrap circuit as the source for creating the BOOT
voltage.
REF_IN
This pin is the third available external pin of the error
amplifier and represents the non-inverting input to the error
amplifier. Connect the desired reference voltage to this pin.
Voltage applied to this pin must not exceed 1.5V.
GND
This pin represents the signal and power ground for the IC.
Tie this pin to the ground island/plane through the lowest
impedance connection available.
CPGND
This pin represents the signal and power ground for the
charge pump. Tie this pin to the ground island/plane through
the lowest impedance connection available.
PHASE
Connect this pin to the upper MOSFET’s source. This pin is
used to monitor the voltage drop across the upper MOSFET
for overcurrent protection.
5
FN9056.10
November 18, 2008
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