sc1152 Semtech Corporation, sc1152 Datasheet - Page 5

• Manufacturer Part Number: sc1152
• Description: Programmable Synchronous Dc/dc Controller For Advanced Processors
• Manufacturer: Semtech Corporation

OUTPUT VOLTAGE TABLE
Unless specified: V
PARAMETER
Output Voltage
April 28, 1998
NOTE:
(1) All VID codes not specifically listed are invalid and cause shutdown exactly as if the shutdown pin had been
asserted.
THEORY OF OPERATION
The voltage at the V
input of the error amplifier. The non-inverting input of the error amplifier is supplied with a DC voltage derived by
the DAC from the internal trimmed bandgap voltage reference. The output of the error amplifier is compared to
the triangular output of the internal oscillator to generate a fixed frequency, variable duty cycle pulse train. The
internal oscillator uses an on-chip capacitor and precision trimmed current sources to set the frequency to 200
kHz.
The generated pulse train is gated with the output of the current limit latch and the inhibit signal to produce a
drive signal for the upper FET. It is also inverted to produce a drive signal for the lower FET. These FET drive
signals are modified by the “shoot-through control” circuitry so that the top FET turn-on is delayed until the bottom
FET has turned off, and visa-versa.
The current limit latch is set (ending the upper FET drive pulse early) if the current limit comparator indicates an
overcurrent condition. The latch is reset at the start of each oscillator period.
The PWRGOOD and OVP signals are derived from the voltage at the V
internal feedback chain.
© 1998 SEMTECH CORP.
(1)
CC
OSENSE
= 4.75V to 5.25V; GND = PGND = 0V; FB = V
pin is applied, through the internal precision resistor feedback chain, to the inverting
I
(Figure 1)
O
= 2A in Application Circuit
CONDITIONS
PROGRAMMABLE SYNCHRONOUS DC/DC
CONTROLLER FOR ADVANCED PROCESSORS
652 MITCHELL ROAD NEWBURY PARK CA 91320
43210
00101
00100
00011
00010
00001
00000
11111
11110
11101
11100
11011
11010
11001
11000
10111
10110
10101
10100
10011
10010
10001
10000
VID
O
; 0mV < (CS(+) - CS(-)) < 60mV; T
OSENSE
1.782
1.832
1.881
1.931
1.980
2.030
1.980
2.079
2.178
2.277
2.376
2.475
2.574
2.673
2.772
2.871
2.970
3.069
3.168
3.267
3.366
3.465
MIN
pin by comparators fed from the
1.800
1.850
1.900
1.950
2.000
2.050
2.000
2.100
2.200
2.300
2.400
2.500
2.600
2.700
2.800
2.900
3.000
3.100
3.200
3.300
3.400
3.500
TYP
1.818
1.868
1.919
1.969
2.020
2.070
2.020
2.121
2.222
2.323
2.424
2.525
2.626
2.727
2.828
2.929
3.030
3.131
3.232
3.333
3.434
3.535
MAX
SC1152
J
= 25° C
UNITS
V
5