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PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
SC1144
1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
Preliminary - August 24, 1999
1
The SC1144 is patent pending
Pentium is a registered trademark of Intel Corporation
BLOCK DIAGRAM
PIN CONFIGURATION
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
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
DEVICE
(1)
PACKAGE
TEMP. (T
J
)
SC1144ABCSW
SO-24
0 - 85C
ORDERING INFORMATION
Note:
(1) Add suffix `TR' for tape and reel.
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.
(24-Pin SOIC)
Top View
PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
SC1144
1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
Preliminary - August 24, 1999
2
The SC1144 is patent pending
ELECTRICAL CHARACTERISTICS
Unless otherwise noted: T
A
= 25
C, V
CC 5V
= 5V, V
CC 12V
= 12V, 4-Phase operation.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Supply Voltage Range
V
CC12V
10.0
12.0
14.0
V
UVLO Range
V
CC5V
3.9
V
UVLO Hystersis
V
CC5V
50
mV
UVLO Range
V
CC12V
9.0
V
UVLO Hystersis
V
CC12V
100
mV
Supply Voltage Range
V
CC5V
4.5
5.0
5.5
V
Supply Current
V
CC12V
DRV Outputs open
12
20
mA
Supply Current
V
CC5V
V
OUT
= 2.00V, I
O
= 0
40
mA
Reference Current Pin Voltage
V
REF
Iref = 250A
2.05
V
Vid0-4 Clock Select & Divide
V
INL
Logic Low
0.8
V
Select Logic Threshold
V
INH
Logic High
2
V
Vid0-4 Clock Select & Divide
I
INL
Vid0-4=0V
-20
A
Select Input Bias Current
I
INH
Vid0-4=4.5V
+50
A
Enable Pin
V
INL
.8
V
V
INH
2
V
DRV0-3 Output Voltage
V
OL
I
sink
= 1mA
.3
V
V
OH
I
source
=1ma,OUTV=V
cc12
V
CC12
-1
V
DRV0-3 Source Current
I
SRC
V
OUT
= 2.00V
20
mA
DRV0-3 Sink Current
I
SNK
V
OUT
= 2.00V
40
mA
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
Limits
Units
V
CC5V
to GND
V
cc5v
-0.3 to + 12
V
FBG to GND
FBG
1
V
V
CC12V
to GND
V
cc12v
-0.3 to +20
V
Operating Temperature Range
T
A
0 to +70
C
Junction Temperature Range
T
J
0 to +125
C
Storage Temperature Range
T
STG
-55 to +150
C
Thermal Resistance Junction to Case
JC
25
C/W
Thermal Resistance Junction to Ambient
JA
80
C/W
Lead Temperature (Soldering) 10 sec
T
LEAD
300
C
PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
SC1144
1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
Preliminary - August 24, 1999
3
The SC1144 is patent pending
ELECTRICAL CHARACTERISTICS (Cont.)
Unless otherwise noted: T
A
= 25
C, V
CC5V
= 5V, V
CC12V
= 12V, 4-Phase operation.
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX UNITS
Bgout Voltage
V
Bgout
Vid = 00000
2.05
V
Bgout Impedance
R
O_Bg
3
K
External Clock Freq. Range
F
ext_CK
.80
8.0
8.5
MHz
Oscillator Frequency Accuracy
F
OSC
Iref = 250A
7.2
8.0
8.8
MHz
Internal Clock Freq. Range
F
int_CK
.80
8.0
8.5
MHz
Match DRV0-3
D
Duty cycle deviation from Avg.
-1
+1
%
PWM Off Time
Toff
25
%
Drive Voltage Range
OutV
Output Freq. = 2MHz/Phase
V
O
= 2.000V
5
10
12
V
Overcurrent Comparator,
Comparator, Common Mode
Range
OCC_CMR
3
15
V
OC+I/P bias Current
IB_OC+
Vin = 5V,Roc+<20Kohm
+75
185
+250
OC-I/P bias Current
IB_OC-
Vin = 5V,Roc-<20Kohm
+75
125
+250
Input Offset Voltage
VOS_OCC
Vin = 5V
10
mV
Feedback Input Impedance
Ri_FB
V
O
= 2.00V
12
Maximum Duty Cycle
Dmax
FB=0V
75
%
Mimimum Duty Cycle
Dmin
FB=4.0V
0
%
CONVERTER SPECIFICATIONS, Reference Application Circuit
Output Accuracy Over Set
Range
V
OUT
VID 0-4 = 0000-1111
V
CC5V
= 5.0V
-1
+1
%
Load Regulation
V
O
= 2.000V
I
O
= 3A - 20A
.025
.05
%/A
Line Regulation
V
CC5V
= 5V,
V
O
= 2.000V
V
IN
= 4-6V, (vin separated from
Vcc5v) I
O
= 5A , Clk = external
.15
%/V
O
OUT
I
V
IN
OUT
V
V
PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
SC1144
1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
Preliminary - August 24, 1999
4
The SC1144 is patent pending
NOTE: (1) All logic inputs and outputs are open collector TTL compatible.
PIN DESCRIPTION
Pin #
Pin Name
Pin Function
1
V
CC 5V
Supply voltage input (5V nominal)
2
Divsel
Connect to Gnd for four phase operation and to logic High for three Phase
operation.
3
Clksel
Clock Select: Logic high selects internal clock. Logic low selects external
clock.
4
Extclk
External Clock Input. The output frequency is determined by (Clock Input
Freq.)/4. Output freq.= (Clock Input)/4. Pull up to Vcc5v to select internal
clock.
5
R
REF
Connects to external reference resistor. Sets the operating frequency of
the internal clock and the ramp time for the PWM. Reference voltage at
this pin is 2.05V. Trimmed to set 250A at 8MHz.
6
VID0
(1)
Programming Input (LSB)
7
VID1
(1)
Programming Input
8
VID2
(1)
Programming Input
9
VID3
(1)
Programming Input
10
VID4
(1)
Programming Input (MSB)
11
OC+
Over current comparator. Non-Inverting input.
12
OC-
Over current comparator. Inverting input.
13
COMP
Compensation Pin. Compensation is acheived by connecting a capacitor in
series with a resistor between this pin and FBG. A 300k ohm resistor must
also be directly connected between this pin and FBG.
14
FB
Feedback input connected to supply output.
15
B
GOUT
Bandgap Reference Output. Output resistance=3kohm. Must be bypassed
with 4.7nf -100nf capacitor to FBG. This capacitor programs the soft start
time.
16
FBG
Feedback Ground. This pin must be connected to return side of output
caps. This pin is floating, (within one diode drop of GND pin).
17
ENABLE
Connects to 5V to enable. Connect to GND to disable entire device.
18
GND
Ground Pin
19
DRV2
Phase 2 output
20
DRV0
Phase 0 output
21
V
CC12V
Supply voltage for the FET Drivers/DRV0-3
22
DRV1
Phase 1 output
23
DRV3
Phase 3 output
24
OutV
Sets the maximum DRV0-3 drive voltage in order to reduce switching
losses in the external MOSFETs.
PROGRAMMABLE, HIGH PERFORMANCE
MULTI-PHASE, PWM CONTROLLER
SC1144
1999 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
Preliminary - August 24, 1999
5
The SC1144 is patent pending
OUTPUT VOLTAGE
Unless specified: 0 = GND; 1 = High (or Floating).
T
A
= 25
C, V
CC5V
= 5V, V
CC12V
= 12V, 4-Phase operation.
PARAMETER
VID
43210
MIN
TYP
MAX
Output Voltage
01111
1.287
1.300
1.313
01110
1.336
1.350
1.364
01101
1.386
1.400
1.414
01100
1.435
1.450
1.465
01011
1.485
1.500
1.515
01010
1.534
1.550
1.566
01001
1.584
1.600
1.616
01000
1.633
1.650
1.667
00111
1.683
1.700
1.717
00110
1.732
1.750
1.768
00101
1.782
1.800
1.818
00100
1.831
1.850
1.869
00011
1.881
1.900
1.919
00010
1.930
1.950
1.970
00001
1.980
2.000
2.020
00000
2.029
2.050
2.071
11111
1.980
2.000
2.020
11110
2.079
2.100
2.121
11101
2.178
2.200
2.222
11100
2.277
2.300
2.323
11011
2.376
2.400
2.424
11010
2.475
2.500
2.525
11001
2.574
2.600
2.626
11000
2.673
2.700
2.727
10111
2.772
2.800
2.828
10110
2.871
2.900
2.929
10101
2.970
3.000
3.030
10100
3.069
3.100
3.131
10011
3.168
3.200
3.232
10010
3.267
3.300
3.333
10001
3.366
3.400
3.434
10000
3.465
3.500
3.535
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