ISL6531 Datasheet, PDF (1/17 Pages) Intersil Corporation – Dual 5V Synchronous Buck Pulse-Width Modulator (PWM) Controller for DDRAM Memory VDDQ and VTT Termination

®
Data Sheet
August 11, 2005
ISL6531
FN9053.2
Dual 5V Synchronous Buck Pulse-Width
Modulator (PWM) Controller for DDRAM
Memory V_DDQ and V_TT Termination
The ISL6531 provides complete control and protection for
dual DC-DC converters optimized for high-performance
DDRAM memory applications. It is designed to drive low
cost N-channel MOSFETs in synchronous-rectified buck
topology to efficiently generate 2.5V V_DDQ for powering
DDRAM memory, V_REF for DDRAM differential signalling,
and V_TT for signal termination. The ISL6531 integrates all of
the control, output adjustment, monitoring and protection
functions into a single package.
The V_DDQ output of the converter is maintained at 2.5V
through an integrated precision voltage reference. The V_REF
output is precisely regulated to 1/2 the memory power
supply, with a maximum tolerance of ±1% over temperature
and line voltage variations. V_TT accurately tracks V_REF.
During V2_SD sleep mode, the V_TT output is maintained by
a low power window regulator.
The ISL6531 provides simple, single feedback loop, voltage-
mode control with fast transient response for the V_DDQ
regulator. The V_TT regulator features internal compensation
that eases the design. It includes two phase-locked 300kHz
triangle-wave oscillators which are displaced 90^o to minimize
interference between the two PWM regulators. The
regulators feature error amplifiers with a 15MHz gain-
bandwidth product and 6V/µs slew rate which enables high
converter bandwidth for fast transient performance. The
resulting PWM duty ratio ranges from 0% to 100%.
The ISL6531 protects against overcurrent conditions by
inhibiting PWM operation. The ISL6531 monitors the current
in the V_DDQ regulator by using the r_DS(ON) of the upper
MOSFET which eliminates the need for a current sensing
resistor.
Ordering Information
TEMP
PART NUMBER RANGE(^oC)
PACKAGE
PKG. DWG. #
ISL6531CB
0 to 70 24 Lead SOIC M24.3
ISL6531CBZ
(See Note)
0 to 70 24 Lead SOIC M24.3
(Pb-free)
ISL6531CR
0 to 70 32 Lead 5x5 QFN L32.5x5
ISL6530/31EVAL1 Evaluation Board
Add “-T” suffix for tape and reel.
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.
Features
• Provides V_DDQ, V_REF, and V_TT voltages for one- and two-
channel DDRAM memory systems
• Excellent voltage regulation
- V_DDQ = 2.5V ±2% over full operating range
-
V_REF =
1_--
2
⋅
V_DDQ
±1%
over
full
operating
range
- V_TT = V_REF ± 30mV
• Supports ‘S3’ sleep mode
-
V_TT is held
regulator to
amt _in¹²--_im⋅ V_{izDeDwQakveia-uaplotiwmepower}
window
• Fast transient response
- Full 0% to 100% duty ratio
• Operates from +5V Input
• V_TT regulator internally compensated
• Overcurrent fault monitor on VDD
- Does not require extra current sensing element
- Uses MOSFET’s r_DS(ON)
• Drives inexpensive N-Channel MOSFETs
• Small converter size
- 300kHz fixed frequency oscillator
• 24 Lead, SOIC or 32 Lead, 5mm×5mm QFN
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• V_DDQ, V_TT, and VREF regulation for DDRAM memory
systems
- Main memory in AMD® Athlon™ and K8™, Pentium®
III, Pentium IV, Transmeta, PowerPC™, AlphaPC™, and
UltraSparc® based computer systems
• High-power tracking DC-DC regulators
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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