SC1102 SC1102A SC1102s SC1102 SC1102A

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Synchronous Voltage Mode Controller Distributed Power Supply Applications
SC1102 SC1102A low-cost, full featured, synchronous voltage-mode controllers designed single ended power supply applications where efficiency primary concern. Synchronous operation allows elimination heat sinks many applications. SC1102s ideal implementing DC/DC converters needed power advanced microprocessors cost systems, distributed power applications where efficiency important. Internal level-shift, high-side drive circuitry, preset shoot-thru control, allows inexpensive N-channel power switches. SC1102s features include temperature compensated voltage reference, triangle wave oscillator current sense comparator circuitry. Power good signaling, shutdown, over voltage protection also provided. SC1102 operates fixed frequency 200kHz SC1102A 500kHz, providing choice optimum compromise between efficiency, external component size, cost. SC1102s used together sequence power telecom systems. power good first SC1102 connected enable second SC1102 makes this possible.
SC1102/SC1102A
Features
1.265V reference available Synchronous operation high efficiency (95%) RDS(ON) current sensing On-chip power good functions Small size with minimum external components Soft Start Enable function SOIC lead free package available. Fully WEEE RoHS compliant
Applications
Microprocessor core supply cost synchronous applications Voltage Regulator Modules (VRM) termination supplies Networking power supplies Sequenced power supplies
Typical Application Circuit
Distributed Typical Distribut Supply
opt. SC1102 10.0 680/6.3V 680/6.3V 680/6.3V
PWRGD PWRGD SS/SHDN
SHDN
VREF
VREF 124*
OCSET
SENSE
MBR0520
PHASE
BSTH
+12V STP40NE STP40NE
DRVH
BSTL
180/4V 180/4V 180/4V 180/4V 180/4V
PGND
DRVL
Vout=2.5V*
Figure
NOTE:
Vout 1.265 (1+R8/R7)
Revision: January 2006
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SC1102/SC1102A
POWER MANAGEMENT Absolute Maximum Ratings
Exceeding specifications below result permanent damage device, device malfunction. Operation outside parameters specified Electrical Characteristics section implied. Exposure Absolute Maximum rated conditions extended periods time affect device reliability.
Parameter VCC, BSTL PGND PHASE BSTH PHASE Thermal Resistance Junction Case Thermal Resistance Junction Ambient Operating Temperature Range Maximum Junction Temperature Storage Temperature Range Lead Temperature (Soldering) Sec.
Note: -1.5V 25ns repetitive every cycle.
Symbol
Maximum -1.0 -0.5
Units °C/W °C/W
TSTG TLEAD
+150
Electrical Characteristics
Unless specified: 4.75V 12.6V; PGND VBSTL 12V; VBSTH-PHASE 12V; 25oC
Parameter Supply Supply Voltage Supply Current Line Regulation Error Amplifier Gain (AOL) Input Bias Oscillator Oscillator Frequency
Conditions
Units
2.5V
12.6
SC1102 SC1102A
Oscillator Duty Cycle MOSFET Drivers Source/Sink Source/Sink BSTH 4.5V, PHASE BSTL 4.5V. PGND.
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SC1102/SC1102A
POWER MANAGEMENT Electrical Characteristics (Cont.)
Unless specified: 4.75V 12.6V; PGND VBSTL 12V; VBSTH-PHASE 12V; 25oC
Parameter PROTECTION Threshold Voltage Source Current Power Good Threshold Dead Time Over current Isink Reference Reference Voltage Accuracy Soft Start Charge Current Discharge Current
Conditions
Units
VOVP 2.0V VOCSET
70°C
1.252
1.265
1.278
1.5V 1.5V
NOTES: Specification refers application circuit (Figure This device sensitive. standard handling precautions required.
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SC1102/SC1102A
POWER MANAGEMENT Configuration
View
Ordering Information
Device
Frequency 200kHz
ackag
SC1102CS.TR SC1102CSTRT(2) SC1102ASTR SC1102ASTRT(2) SC1102EVB 500kHz Evaluation Board SO-14
(14-Pin SOIC)
Descriptions
Name PWRGD OCSET PHASE PGND BSTL BSTH SENSE VREF SS/SHDN Function
Notes: Only available tape reel packaging. reel contains 2500 devices. Lead free product. This product fully WEEE RoHS compliant.
Chip supply voltage Logic high indicates correct output voltage Over voltage protection. Sets converter overcurrent trip point Input from phase node between MOSFET'S High side driver output Power ground side driver output Bootstrap, side driver. Bootstrap, high side driver. Voltage sense input Buffered band voltage reference. Soft start. capacitor ground sets slow start time. Signal ground
NOTE: logic level inputs outputs open collector compatible.
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SC1102/SC1102A
POWER MANAGEMENT Block Diagram
Applications Information Theory Operation
Synchronous Buck Converter Primary VCORE power provided synchronous, voltage-mode pulse width modulated (PWM) controller. This section features required build high efficiency synchronous buck converter, including "Power Good" flag, shut-down, cycle-by-cycle current limit. output voltage synchronous converter controlled output error amplifier. external resistive divider reference voltage derived from internal trimmed-bandgap voltage reference (See Fig. inverting input error amplifier receives voltage from SENSE pin. internal oscillator uses on-chip capacitor trimmed precision current sources oscillation frequency 200kHz/500kHz. triangular output oscillator sets reference voltage inverting input comparator. non-inverting input comparator receives it's input voltage from error amplifier. When oscillator output voltage drops below error amplifier output voltage, comparator output goes high. This pulls low, turning low-side FET, pulled high, turning high-side (once cross-current control allows it). When oscillator voltage rises back above error amplifier output voltage, comparator output goes low. This pulls
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low, turning high-side FET, pulled high, turning low-side (once cross-current control allows it). SENSE increases, output voltage error amplifier decreases. This causes reduction ontime high-side MOSFET connected hence lowering output voltage. Under Voltage Lockout under voltage lockout circuit SC1102 assures that high-side MOSFET driver outputs remain state whenever supply voltage drops below parameters. Lockout occurs falls below 4.1V. Normal operation resumes once rises above 4.2V. Over-Voltage Protection over-voltage protection (OVP) high only when voltage SENSE higher than target value programmed external resistor divider. internally connected PNP's collector. Power Good power good function confirm that regulator outputs within +/-10% programmed level. PWRGD remains high long this condition met. PWRGD connected internal open collector transistor.
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SC1102/SC1102A
POWER MANAGEMENT Applications Information (Cont.)
Soft Start Initially, SS/SHDN sources 10µA current charge external capacitor. outputs error amplifiers clamped voltage proportional voltage SS/SHDN. This limits on-time high-side MOSFETs, thus leading controlled ramp-up output voltages. RDS(ON) Current Limiting current limit threshold connecting external resistor from supply OCSET. voltage drop across this resistor 200µA internal sink sets voltage pin. This voltage compared voltage PHASE node. This comparison made only when high-side drive high avoid false current limit triggering uncontributing measurements from MOSFETs off-voltage. When voltage PHASE less than voltage OCSET, overcurrent condition occurs soft start cycle initiated. synchronous switch turns SS/SHDN starts sink 2µA. When SS/SHDN reaches 0.8V, then starts source 10µA cycle begins. Hiccup Mode During power SS/SHDN internally pulled until reaches undervoltage lockout level 4.2V. Once reached 4.2V, SS/SHDN released begins source 10µA current external soft-start capacitor. soft-start voltage rises, output internal error amplifier clamped this voltage. When error signal reaches level internal triangular oscillator, which swings from fixed frequency 200kHz/500kHz, switching occurs. error signal crosses over oscillator signal, duty cycle signal continues increase until output comes into regulation. overcurrent condition occurred soft-start voltage will continue rise level about 2.2V. over-current condition occurs when high-side drive turned PHASE node does reach voltage level OCSET pin. PHASE node sampled only once cycle during valley triangular oscillator. Once over-current occurs, highside drive turned low-side drive turns SS/SHDN begins sink 2uA. soft-start voltage will begin decrease current discharges external capacitor. When soft-start voltage reaches 0.8V, SS/SHDN will begin source 10uA begin charge external capacitor causing soft-start voltage rise again. Again, when softstart voltage reaches level internal oscillator, switching will occur. over-current condition longer present, normal operation will continue. over-current condition still present, SS/SHDN will again begin sink 2uA. This cycle will continue indefinitely until overcurrent condition removed. conclusion, below shown typical "12V Application Circuit" which BSTH voltage derived bootstrapping input voltage PHASE node through diode This circuit very useful cases where only input power available. order prevent substrate glitching, small-signal diode should placed close proximity chip with cathode connected PHASE anode connected PGND.
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SC1102/SC1102A
POWER MANAGEMENT Application Circuit
Typical Application Circuit with Bootstrapped BSTH
1.74k opt. PWRGD PWRGD SS/SHDN SC1102 SHDN 10.0 MBRA130 270/16V 270/16V 270/16V
VREF VREF PHASE BSTH PGND DRVL STP40NE STP40NE
205*
OCSET
SENSE
MBR0520
DRVH
BSTL
MBRD1035 Optional 180/4V 180/4V 180/4V 180/4V 180/4V
Vout=3.3V*
NOTE:
Vout 1.265 (1+R9/R8)
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SC1102/SC1102A
POWER MANAGEMENT Typical Characteristics
Output Ripple Voltage Ch1: Vo_rpl 3.3V; IOUT Wave forms shown SC1102 similiar SC1102A higher frequency. Gate Drive Waveforms Ch1: Ch2: Bottom
Descriptions
Ch1: Vo_rpl VOUT 1.3V; IOUT
Ch1: Ch2: Bottom
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SC1102/SC1102A
POWER MANAGEMENT Typical Characteristics (Cont.)
Ch1: Vo_rpl VOUT 1.3V; IOUT Ch1: Ch2: Bottom
Error Amplifier, Gain Phase
Descriptions
Gain (dB) Gain 100.0E+0 Phase
1.0E+3
10.0E+3
100.0E+3
1.0E+6
10.0E+6
Frequency (Hz)
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Phase (deg)
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SC1102/SC1102A
POWER MANAGEMENT Typical Characteristics (Cont.)
Hiccup Mode
Ch1: Ch2: Ch3: Ch4:
Gate Vout
Vout 3.3V Vbst Iout S.C.
Start Mode
Ch1: Ch2: Ch3: Gate Ch4: Vout Vout 3.3V Iout Vbst
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POWER MANAGEMENT Evaluation Board Schematic
Vbias
PWRGD VREF SS/SHDN SHDN
PWRGD
PHASE BSTH VREF OCSET SENSE DRVH BSTL PGND DRVL
Vout
SC1102/SC1102A
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SC1102/SC1102A
POWER MANAGEMENT Outline Drawing S0IC
DIMENSIONS INCHES MILLIMETERS
.053 .069 .010 .004 .065 .049 .020 .012 .007 .010 .337 .341 .344 .150 .154 .157 .236 .050 .010 .020 .016 .028 .041 (.041) .004 .010 .008 1.35 1.75 0.25 0.10 1.65 1.25 0.31 0.51 0.25 0.17 8.55 8.65 8.75 3.80 3.90 4.00 6.00 1.27 0.25 0.50 0.40 0.72 1.04 (1.04) 0.10 0.25 0.20
TIPS
SEATING PLANE
GAGE PLANE 0.25
SIDE VIEW
NOTES:
DETAIL
(L1) DETAIL
CONTROLLING DIMENSIONS MILLIMETERS (ANGLES DEGREES).
DATUMS DETERMINED DATUM PLANE -H3. DIMENSIONS "E1" INCLUDE MOLD FLASH, PROTRUSIONS GATE BURRS. REFERENCE JEDEC MS-012, VARIATION
Land Pattern SOIC
DIMENSIONS INCHES MILLIMETERS
(.205) .118 .050 .024 .087 .291 (5.20) 3.00 1.27 0.60 2.20 7.40
NOTES: THIS LAND PATTERN REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES MET. REFERENCE IPC-SM-782A, 302A.
Contact Information
Semtech Corporation Power Management Products Division Flynn Road, Camarillo, 93012 Phone: (805)498-2111 (805)498-3804
2006 Semtech Corp. www.semtech.com

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