DESCRIPTION SC1152 low-cost, full featured, synchronous voltage-m

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DESCRIPTION SC1152 low-cost, full featured, synchronous voltage-m

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SC1152
DESCRIPTION
SC1152 low-cost, full featured, synchronous voltage-mode controller designed single ended power supply applications where efficiency primary concern. Synchronous operation allows elimination heat sinks many applications. SC1152 ideal implementing DC/DC converters needed power advanced microprocessors such Pentium (Klamath), both single multiple processor configurations. Internal level-shift, high-side drive circuitry, preset shoot-thru control, allows inexpensive n-channel power switches. SC1152 features include integrated 5-bit DAC, temperature compensated voltage reference, triangle wave oscillator, current limit comparator, frequency shift over-current protection, accessible, internally compensated error amplifier. Power good signaling, logic compatible shutdown, over voltage protection also provided. SC1152 operates fixed 200KHz, providing optimum compromise between efficiency, external component size, cost.
FEATURES
cost full featured Synchronous operation programmable output On-chip power good functions Designed meet Intel VRM8.1 (Pentium
APPLICATIONS
Pentium® (Klamath) Core Supply Multiple Microprocessor Supplies Voltage Regulator Modules (VRM) Programmable Power Supplies High Efficiency DC/DC Conversion
ORDERING INFORMATION
DEVICE
PACKAGE SO-20
TEMP. RANGE (TJ) 125°C
SC1152CS
Note: suffix `TR' tape reel.
CONFIGURATION
BLOCK DIAGRAM
View
CS(-) CS(+) CURRENT LIMIT VID4 VID3 VID2 VID1 VID0 70mV UPPER LEVEL SHIFT DRIVE BSTH SHUTDOWN
1.25V
SHUTDOWN LOGIC
DECODED SHUTDOWN SIGNAL OSCILLATOR
PGNDH
VOSENSE OPEN COLLECTORS
PWRGOOD SYNCHRONOUS
ERROR
SHOOT-THRU CONTROL BSTL
(20-Pin SOIC)
DRIVE
PGNDL
Pentium registered trademark Intel Corporation
1998 SEMTECH CORP.
MITCHELL ROAD NEWBURY PARK 91320
SC1152
ABSOLUTE MAXIMUM RATINGS
Parameter Symbol PGND Thermal Resistance Junction Case Thermal Resistance Junction Ambient Operating Temperature Range Storage TSTG Temperature Range Lead Temperature TLEAD (Soldering) Maximum -0.3 -0.3 +150 Units °C/W °C/W
ELECTRICAL CHARACTERISTICS
Unless specified: 4.75V 5.25V; PGND (CS(+) CS(-)) 60mV; PARAMETER Output Voltage Supply Voltage Supply Current Load Regulation Line Regulation Gain (AOL) Current Limit Voltage Oscillator Frequency Oscillator Duty Cycle Sink/Source Current Sink/Source Current Threshold Voltage Source Current Power Good Threshold Voltage Dead Time NOTE: Specification refers application circuit (Figure 1.). VOVP BSTH 4.5V, PGNDH BSTL 4.5V, PGNDL 0.3A codes VOSENSE
CONDITIONS
Table
UNITS
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320
SC1152
DESCRIPTION
NOTE: logic level inputs outputs open collector compatible. Name PWRGOOD CS(-) CS(+) PGNDH PGNDL BSTL BSTH SHUTDOWN VOSENSE VID4 VID3 VID2 VID1 VID0
Function Small Signal Analog Digital Ground Chip Supply Voltage High Signal Setpoint Open collector logic output, high within setpoint Current Sense Input (negative) Current Sense Input (positive) Power Ground High Side Switch High Side Driver Output Connected Power Ground Side Switch Side Driver Output Side Driver (Boost) High Side Driver (Boost) Logic shuts down converter internal feedback chain Programming Input (MSB) Programming Input Programming Input Programming Input Programming Input (LSB)
CONFIGURATION
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320
SC1152
APPLICATION CIRCUIT
5mOhm 1000uF 1000uF 1000uF
1000uF 0.1uF 1000uF 1000uF
VCCP
1N5817
1000uF
1000uF
1000uF
0.1uF
VID0 VID1 VID2 VID3 SHUTDOWN PGNDL SC1152CS CS(+) CS(-) 2.32k 0.1uF 1.00k
VID0 VID1 VID2 VID3 VID4
0.1uF
VOSENSE
PWRGOOD VID4 BSTH PGNDH BSTL
SHUTDOWN PWRGOOD
Pentium Power Supply Figure
MATERIALS LIST
Quantity Reference Part/Description Vendor Various SANYO Various Turns 16AWG MICROMETALS T50-52D core notes Various Various Various Various SEMTECH selection requires trade-off between efficiency cost. Absolute maximum RDS(ON) OAR-1 Series MV-GX equiv. Notes C1,C11-C13 0.1µF Ceramic C2-C10 1000µF/6.3V 1N5817 notes 10k, 1/8W 2.32k, 1/8W 1/8W 1/8W SC1152CS
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320
SC1152
OUTPUT VOLTAGE TABLE
Unless specified: 4.75V 5.25V; PGND (CS(+) CS(-)) 60mV; 25°C PARAMETER Output Voltage
CONDITIONS Application Circuit (Figure
43210 00101 00100 00011 00010 00001 00000 11111 11110 11101 11100 11011 11010 11001 11000 10111 10110 10101 10100 10011 10010 10001 10000
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
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
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
UNITS
NOTE: codes specifically listed invalid cause shutdown exactly shutdown been asserted.
THEORY OPERATION
voltage VOSENSE applied, through internal precision resistor feedback chain, inverting input error amplifier. non-inverting input error amplifier supplied with voltage derived from internal trimmed bandgap voltage reference. output error amplifier compared triangular output internal oscillator generate fixed frequency, variable duty cycle pulse train. internal oscillator uses on-chip capacitor precision trimmed current sources frequency kHz. generated pulse train gated with output current limit latch inhibit signal produce drive signal upper FET. also inverted produce drive signal lower FET. These drive signals modified "shoot-through control" circuitry that turn-on delayed until bottom turned off, visa-versa. current limit latch (ending upper drive pulse early) current limit comparator indicates overcurrent condition. latch reset start each oscillator period. PWRGOOD signals derived from voltage VOSENSE comparators from internal feedback chain.
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320
SC1152
CHARACTERISTIC CURVES
SC1152 Efficiency Application Circuit (Figure
95.0%
90.0%
3.50 Volts 3.00 Volts 85.0%
2.00 Volts
2.50 Volts
Efficiency 80.0%
1.80 Volts
75.0%
70.0% 0.000
2.000
4.000
6.000
8.000 Output Current (Amps)
10.000
12.000
14.000
16.000
SC1152 Regulation Application Circuit (Figure
0.000
-0.005
Delta
-0.010
Delta Vout -0.015 Delta
-0.020
Delta Delta -0.025 0.000 2.000 4.000 6.000 8.000 Output Current (Amps) 10.000 12.000 14.000 16.000
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320
SC1152
OUTLINE DRAWING SO-20
Ref. MS-013AC
1998 SEMTECH CORP. MITCHELL ROAD NEWBURY PARK 91320

DESCRIPTION SC1152 low-cost, full featured, synchronous voltage-m

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