February 8, 2005
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 VDDQ during S0/S1 and S3 states. During S0/S1
state, a fully integrated sink-source regulator generates an
accurate (VDDQ/2) high current VTT voltage without the
need for a negative supply. A buffered version of the VDDQ/2
www.DataShereeft4eUre.cnocme is provided as VREF. Two LDO controllers are also
integrated for the GMCH core voltage regulation and for the
GMCH and CPU VTT 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 VTT termination voltage
is within spec and operational.
Each output is monitored for undervoltage events. The
switching regulator also has overvoltage and over current
protection. Thermal shutdown is integrated.
ISL6537 (6x6 QFN)
28 27 26 25 24 23 22
8 9 10 11 12 13 14
• Generates 4 Regulated Voltages
- Synchronous Buck PWM Controller for DDR VDDQ
- 3A Integrated Sink/Source Linear Regulator with
Accurate VDDQ/2 Divider Reference for DDR VTT
- LDO Regulator for GMCH Core
- LDO Regulator for CPU/GMCH VTT Termination
• ACPI compliant sleep state control
• Glitch-free Transitions During State Changes
• Integrated VREF 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 Over-voltage Monitoring on All Outputs
• OCP on the Switching Regulator
• Integrated Thermal Shutdown Protection
• Pb-Free Available (RoHS Compliant)
• 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
0 to 70
28 Ld 6x6 QFN L28.6x6
0 to 70
28 Ld 6x6 QFN L28.6x6
*Add “-T” suffix to part number for tape and reel packaging.
NOTE: Intersil Pb-free 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.
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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