1
®
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ISL6537
ACPI Regulator/Controller for
Dual Channel DDR Memory Systems
The ISL6537 provides a complete ACPI compliant power
solution for up to 4 DIMM dual channel DDR/DDR2 Memory
systems. Included are both a synchronous buck controller to
supply V
DDQ
during S0/S1 and S3 states. During S0/S1
state, a fully integrated sink-source regulator generates an
accurate (V
DDQ
/2) high current V
TT
voltage without the
need for a negative supply. A buffered version of the V
DDQ
/2
reference is provided as V
REF
. Two LDO controllers are also
integrated for the GMCH core voltage regulation and for the
GMCH and CPU V
TT
termination voltage regulation.
The switching PWM controller drives two N-Channel
MOSFETs in a synchronous-rectified buck converter
topology. The synchronous buck converter uses voltage-
mode control with fast transient response. The switching
regulator provides a maximum static regulation tolerance of
±2% over line, load, and temperature ranges. The output is
user-adjustable by means of external resistors down to 0.8V.
An integrated soft-start feature brings all outputs into
regulation in a controlled manner when returning to S0/S1
state from any sleep state. During S0 the VIDPGD signal
indicates that the GMCH and CPU V
TT
termination voltage
is within spec and operational.
Each output is monitored for undervoltage events. The
switching regulator also has overvoltage and overcurrent
protection. Thermal shutdown is integrated.
Pinout
ISL6537 (6x6 QFN)
TOP VIEW
Features
• Generates 4 Regulated Voltages
- Synchronous Buck PWM Controller for DDR V
DDQ
- 3A Integrated Sink/Source Linear Regulator with
Accurate VDDQ/2 Divider Reference for DDR V
TT
- LDO Regulator for GMCH Core
- LDO Regulator for CPU/GMCH V
TT
Termination
• ACPI Compliant Sleep State Control
• Glitch-free Transitions During State Changes
• Integrated V
REF
Buffer
• PWM Controller Drives Low Cost N-Channel MOSFETs
• 250kHz Constant Frequency Operation
• Tight Output Voltage Regulation
- All Outputs: ±2% Over Temperature
• Fully-Adjustable Outputs with Wide Voltage Range: Down
to 0.8V supports DDR and DDR2 Specifications
• Simple Single-Loop Voltage-Mode PWM Control Design
• Fast PWM Converter Transient Response
• Under and Overvoltage Monitoring on All Outputs
• OCP on the Switching Regulator
• Integrated Thermal Shutdown Protection
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
•
Single and Dual Channel DDR Memory Power Systems in
ACPI Compliant PCs
•
Graphics Cards - GPU and Memory Supplies
• ASIC Power Supplies
• Embedded Processor and I/O Supplies
• DSP Supplies
1
2
3
4
5
6
7
21
20
19
18
17
16
15
28 27 26 25 24 23 22
8 9 10 11 12 13 14
DRIVE4
REFADJ4
DRIVE3
FB3
FB4
COMP
FB
5VSBY
S3#
P12V
GND
DDR_VTT
DDR_VTT
VDDQ
VDDQ
DDR_VTTSNS
DRIVE2
FB2
VIDPGD
VREF_OUT
VREF_IN
LGATE
GND
UGATE
BOOT
PHASE
S5#
OCSET
GND
29
Ordering Information
PART
NUMBER
PART
MARKING
TEMP.
RANGE (°C) PACKAGE
PKG.
DWG. #
ISL6537CR ISL6537CR 0 to +70 28 Ld 6x6 QFN L28.6x6
ISL6537CRZ
(See Note)
ISL6537CRZ 0 to +70 28 Ld 6x6 QFN
(Pb-free)
L28.6x6
*Add “-T” suffix to part number for tape and reel packaging.
NOTE: Intersil Pb-free plus anneal products employ special Pb-free
material sets; molding compounds/die attach materials and 100%
matte tin plate termination finish, which are 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.
Data Sheet July 18, 2007 FN9142.6
