VRM9.0 PROGRAMMABLE, MULTI-PHASE,
HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DESCRIPTION
The SC1146 is the latest, high performance, multi-
phase (PWM) controller designed for high power mi-
croprocessors requiring ultra fast transient response.
The SC1146 is programmable for the voltage range
required by the latest Microprocessors . 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 ap-
proach greatly reduces the stress and heat on the out-
put stage components while lowering input ripple cur-
rent by as much as 80%. Accurate current sharing
among the four phases is achieved by precision design
techniques and trimming of critical elements.
The high speed transconductance error amplifier is ex-
ternally initialized using a soft-start capacitor allowing
the controller to “wake-up” without overshoot, thus pro-
tecting the low voltage microprocessor loads. The out-
put drive voltage to the power MOSFETs is pro-
grammable to minimize switching losses in the drive
circuitry.
The output voltage is digitally programmable by means
of a 5 bit DAC (new codes). A single resistor programs
the master clock frequency (8MHz max) or the clock
can be supplied by an external source where exact fre-
quency control is desired. 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
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Allows use of small surface mount components
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Ultra fast transient recovery time
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Dramatic reduction of input ripple current and out-
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put ripple voltage
5-bit programmable DAC for the latest, lower
output voltage Microprocessors
Wide, High frequency operating range
Selectable 2, 3, 4 phase operation
+5 Volt only operation eliminates the need for
+12V supply
Precision load current sharing,1%PWM match
Selectable internal or external clock
Soft start/UVLO/Over current protection
APPLICATIONS
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High end servers and workstations
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High current/Ultra-fast transient microprocessors
ORDERING INFORMATION
DEVICE
(1)
PACKAGE
SO-24
TEMP. (T
J
)
0 - 85°C
SC1146CSW.TR
Note:
(1) Only available in tape and reel packaging. A reel
contains 1000 devices.
BLOCK DIAGRAM
PIN CONFIGURATION
Top View
(24-Pin SOIC)
The SC1146 is patent pending
Pentium is a registered trademark of Intel Corporation
1
© 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
SEMTECH [ SEMTECH CORPORATION ]
