
1
FN9069.3
ISL6444
Dual PWM Controller with DDR Memory 
Option for Gateway Applications
The ISL6444 PWM controller provides high efficiency and 
regulation for two output voltages adjustable in the range from 
0.9V to 5.5V that are required to power I/O, chip-sets, and 
memory banks in high-performance notebook computers, 
PDAs, and Internet appliances. 
Synchronous rectification and hysteretic operation at light 
loads contribute to a high efficiency over a wide range of 
loads. The hysteretic mode of operation can be disabled 
separately on each PWM converter if continuous conduction 
operation is desired for all load levels. Efficiency is even 
further enhanced by using MOSFET’s r
DS(ON)
 as a current 
sense component. 
Feed-forward ramp modulation, current mode control 
scheme, and internal feed-back compensation provide fast 
response to load transients. Out-of-phase operation with a 
180
o
 phase shift reduces the input current ripple. 
The controller can be transformed in a complete DDR 
memory power supply solution by activating a DDR pin. In 
DDR mode of operation one of the channels tracks the 
output voltage of another channel and provides output 
current sink and source capability–features essential for 
proper powering of DDR chips. The buffered reference 
voltage required by this type of memory is also provided.
The ISL6444 monitors the output voltages. Each PWM 
controller generates a PGOOD (power good) signal when 
the soft-start is completed and the output is within ±10% of 
the set point. 
A built-in overvoltage protection prevents output voltage 
from going above 115% of the set point. Normal operation 
automatically restores when the overvoltage conditions go 
away. Undervoltage protection latches the chip off when 
either output drops below 75% of its set value after the 
soft-start sequence for this output is completed. An 
adjustable overcurrent function monitors the output current 
by sensing the voltage drop across the lower MOSFET. If 
precision current-sensing is required, an external current-
sense resistor may optionally be used. 
The IC comes in a 28 Ld SSOP package. 
Features
 Provides regulated output voltage in the range 0.9V to 5.5V
- High efficiency over wide load range
- Synchronous buck converter with hysteretic operation at 
light load
 Complete DDR memory power solution
- VTT tracks VDDQ/2
- VDDQ/2 buffered reference output
 No current-sense resistor required
- Uses MOSFET’s r
DS(ON)
- Optional current-sense resistor for precision overcurrent
 Undervoltage lock-out on VCC pin
 Dual mode operation
- Operates directly from battery 5.0V to 24V input
- Operates from 3.3V or 5V system rail
 Excellent dynamic response
- Combined voltage feed-forward and current mode 
control
 Power-good signal for each channel
 300kHz switching frequency
- Out-of-phase operation for reduced input ripple
- In-phase operation in DDR mode for reduced channel 
interference
- Out-of-phase operation with 90° phase shift for 
two-stage conversion in DDR mode
 Pb-free plus anneal available (RoHS compliant)
Applications
 Residential and Enterprise Gateways
 DSL Modems
 Routers and Switchers
Ordering Information
PART 
NUMBER
PART 
MARKING
TEMP. 
RANGE 
(°C)
PACKAGE
PKG. 
DWG. #
ISL6444CA*
ISL 6444CA
-10 to +85
28 Ld QSOP M28.15
ISL6444CAZ* 
(Note)
ISL 6444CAZ
-10 to +85
28 Ld QSOP 
(Pb-free)
M28.15
*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.
Data Sheet
April 12, 2007
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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