PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
Preliminary - August 24, 1999
SC1144
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1144 is a high performance, multi-phase
(PWM) controller designed for high power micropro-
cessors requiring ultra fast transient response, such as
®
the Pentium ll and beyond. Utilizing a novel and
unique design, the controller distributes the output load
across (up to) four converter channels by digitally
phase shifting the PWM outputs. This approach
greatly reduces the stress and heat on the output
stage components while lowering input ripple current
by as much as 80%. Accurate current sharing among
the four phases is achieved by precision design tech-
niques and trimming of critical elements.
The high speed transconductance error amplifier is
externally initialized using a soft-start capacitor allow-
ing the controller to “wake-up” without overshoot, thus
protecting the low voltage microprocessor loads. The
output drive voltage to the power MOSFETs is pro-
grammable to minimize switching losses in the drive
circuitry.
The floating feedback ground allows remote sense ca-
pability. The output voltage is digitally programmable
by means of a 5 bit DAC. A single resistor programs
the master clock frequency (8MHz max) or the con-
troller may be synchronized using an external oscilla-
tor. The number of operating phases is programmed
independently of the external clock. The parts features
under-voltage lock-out with hysteresis and over-
current protection.
FEATURES
•
Allows use of small surface mount components
•
Ultra fast transient recovery time
•
Wide, High frequency operating range
•
Selectable 2, 3, 4 phase operation
•
Floating feedback ground for remote sensing
•
Precision load current sharing
•
Selectable internal or external clock
•
Soft start, Over current protection
•
5-bit DAC programmable output
•
programmable clock, 200Khz-2Mhz per phase
APPLICATIONS
•
High end servers and workstations
•
High current/Ultra-fast transient microprocessors
•
Voltage Regulator Modules
ORDERING INFORMATION
DEVICE
(1)
PACKAGE
SO-24
TEMP. (T
J
)
0 - 85°C
SC1144ABCSW
Note:
(1) Add suffix ‘TR’ for tape and reel.
BLOCK DIAGRAM
PIN CONFIGURATION
Top View
(24-Pin SOIC)
The SC1144 is patent pending
Pentium is a registered trademark of Intel Corporation
1
© 1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH [ SEMTECH CORPORATION ]
