SP7661ER/TR [SIPEX]
Wide Input Voltage Range 3A, 600kHz, Buck Regulator; 宽输入电压范围3A ， 600kHz的，降压型稳压器
| 型号： | SP7661ER/TR |
| 厂家： | 
SIPEX CORPORATION |
| 描述： | Wide Input Voltage Range 3A, 600kHz, Buck Regulator |
| 文件： | 总20页 (文件大小：1039K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SP7661
Wide Input Voltage Range
3A, 600kHz, Buck Regulator
TM
Power
Blox
SP7661
DFN PACKAGE
7mm x 4mm (Option 2)
FEATURES
■ꢀ 4.75Vꢀtoꢀ22VꢀInputꢀVoltageꢀRangeꢀusingꢀSingleꢀSupply
■ꢀ 3Vꢀtoꢀ22VꢀInputꢀVoltageꢀRangeꢀusingꢀDualꢀSupply
■ꢀ ±1%ꢀ0.8VꢀReference
26
25
24
23
22
21
P
P
P
1
2
3
LX
LX
LX
GND
BOTTOM VIEW
GND
GND
■ꢀ 3AꢀOutputꢀCapability
Heatsink Pad 1
Connect to Lx
■ꢀ CurrentꢀLimitingꢀusingꢀInductorꢀDCR
■ꢀ BuiltꢀinꢀLowꢀRDS(ON) ꢀPowerꢀSwitches
■ꢀ 600kHzꢀFixedꢀFrequencyꢀOperation
■ꢀ OverꢀTemperatureꢀProtection
P
4
5
LX
CC
GND
Pin 27
GND
V
6
7
UV
V
FB
IN
COMP
SS
20
19
18
17
GND
GND
■ꢀ ShortꢀCircuitꢀProtectionꢀwithꢀAuto-Restart
■ꢀ WideꢀBWꢀAmpꢀAllowsꢀTypeꢀIIꢀorꢀIIIꢀCompensation
■ꢀ ProgrammableꢀSoftꢀStart
Heatsink Pad 2
Connect to GND
8
9
GND
ISN
V
IN
Pin 28
10
■ꢀ FastꢀTransientꢀResponse
BST
LX
■ꢀ HighꢀEfficiency:ꢀGreaterꢀthanꢀ93%ꢀPossible
■ꢀ NonsynchronousꢀStart-UpꢀintoꢀaꢀPre-ChargedꢀOutput
■ꢀ AvailableꢀinꢀRoHSꢀCompliant,ꢀLeadꢀFreeꢀPackaging:
Heatsink Pad 3
Connect to VINP
11
12
13
16
ISP
SWN
LX 15
14
Pin 29
LX
VINP
ꢀ
Smallꢀ7mmꢀxꢀ4mmꢀDFNꢀ
■ꢀ U.S.ꢀPatentꢀ#6,922,041
DESCRIPTION
TheꢀSP7661ꢀisꢀaꢀsynchronousꢀstep-downꢀswitchingꢀregulatorꢀꢀoptimizedꢀforꢀhighꢀefficiency.ꢀꢀTheꢀpartꢀisꢀdesignedꢀ
forꢀuseꢀwithꢀaꢀsingleꢀ4.75Vꢀtoꢀ22Vꢀsingleꢀsupplyꢀorꢀ3Vꢀtoꢀ22VꢀinputꢀifꢀanꢀexternalꢀVccꢀisꢀprovided.ꢀTheꢀSP7661ꢀ
providesꢀaꢀfullyꢀintegratedꢀbuckꢀregulatorꢀsolutionꢀusingꢀaꢀfixedꢀ600kHzꢀfrequency,ꢀPWMꢀvoltageꢀmodeꢀarchitecture.ꢀ
ProtectionꢀfeaturesꢀincludeꢀUVLO,ꢀthermalꢀshutdown,ꢀoutputꢀcurrentꢀlimitꢀandꢀshortꢀcircuitꢀprotection.ꢀTheꢀSP7661ꢀ
isꢀavailableꢀinꢀtheꢀspaceꢀsavingꢀDFNꢀpackage.
TYPICAL APPLICATION CIRCUIT
VIN 12V (9.6V-22V)
ꢀ
VOUT
ꢀ
3.30V, 0-3A
C2
Cꢀ
L1,ꢀWurthꢀ-744311220
2.2uH,ꢀ14ꢀmOhm,ꢀ7x7mm,ꢀ9A
22uF 22uF
LX
ꢀ
3
ꢀ
R3
5.11k
R4
5.11k
2
GND
C5
C4 47nF
ꢀ
2
26
25
24
23
22
2ꢀ
20
19
18
ꢀ7
ꢀ6
15
14
PGND
PGND
PGND
PGND
GND
VFB
LX
100uF
R9
ISP
61.9k
VFB
LX
LX
ISN
RZ3
ꢀ
RZ2
4.02k
56pF
3
CZ2
U1
400
4
Rꢀ
4
CVCC
ꢀ0k
SP7661
LX
6800pF
4.7uF
GND
5
VCC
UVIN
GND
GND
VIN
BST
LX
CZ3
1500pF
CPꢀ
6
NC
7
COMP
SS
VFB
CSS 47nF
R2
CF1
100pF
8
3.16k
9
GND
ISN
ꢀ0
ꢀꢀ
ꢀ2
ꢀ3
ISP
SD101AWS
DBST
C9 6.8nF
SWN
VIN
LX
22nF
LX
CBST
ISN
ISP
LX
LX
Rs2
Cs2
1ꢀOhm 2.2nF
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ
StorageꢀTemperature
PowerꢀDissipation........................................InternallyꢀLimitedꢀviaꢀOTP
LeadꢀTemperatureꢀ(Soldering,ꢀ10ꢀsec)ꢀ.......................................300°C
ESDꢀRating........................................................................... 2kV HBM
................................................... -65°Cꢀtoꢀ150°C
ABSOLUTE MAXIMUM RATINGS
Theseꢀareꢀstressꢀratingsꢀonlyꢀandꢀfunctionalꢀoperationꢀofꢀtheꢀdeviceꢀatꢀtheseꢀratingsꢀorꢀanyꢀotherꢀaboveꢀthoseꢀindicatedꢀinꢀtheꢀoperationꢀsectionsꢀ
ofꢀtheꢀspecificationsꢀbelowꢀisꢀnotꢀimplied.ꢀExposureꢀtoꢀabsoluteꢀmaximumꢀratingꢀconditionsꢀforꢀextendedꢀperiodsꢀofꢀtimeꢀmayꢀaffectꢀreliability.
VCCꢀ...................................................................................................7V
ViNꢀꢀ.................................................................................................25V
BST................................................................................................ 30V
LX-BSTꢀ...............................................................................-0.3Vꢀtoꢀ7V
LXꢀ........................................................................................-ꢀV to 30V
Allꢀotherꢀpins..........................................................-0.3VꢀtoꢀVCC +ꢀ0.3V
ThermalꢀResistanceꢀθJCꢀ........................................................... ꢀ5°C/Wꢀ
ELECTRICAL SPECIFICATIONS
SpecificationsꢀareꢀforꢀTAMB =ꢀTJ =ꢀ25°C,ꢀandꢀthoseꢀdenotedꢀbyꢀ♦ꢀapplyꢀoverꢀtheꢀfullꢀoperatingꢀrange,ꢀ-40°C<ꢀTj<ꢀ125°C.ꢀꢀUnlessꢀ
otherwiseꢀspecified:ꢀ4.5Vꢀ<ꢀVccꢀ<ꢀ5.5V,ꢀ3Vꢀ<ꢀViNꢀ<ꢀ22V,ꢀBSTꢀ=ꢀLXꢀ+ꢀ5V,ꢀUVINꢀ=ꢀ3V,ꢀCVCCꢀ=ꢀ1µF,ꢀCCOMPꢀ=ꢀ0.1µF,ꢀCssꢀ=ꢀ50nF.ꢀ
UNITS
PARAMETER
QUIESCENT CURRENT
MIN TYP MAX
♦
♦
CONDITIONS
V
iNꢀSupplyꢀCurrentꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀ
(Noꢀswitching)
iNꢀSupplyꢀCurrentꢀ
1.5
8
3.0
14
0.4
6
mA
mA
V
V
fB=ꢀ0.9V
V
(switching)
BSTꢀSupplyꢀCurrentꢀꢀꢀꢀꢀꢀꢀꢀꢀ
(Noꢀswitching)
0.2
3
fB=ꢀ0.9V
mA ♦
BSTꢀSupplyꢀCurrentꢀ
(switching)
mA
PROTECTION: UVLO
VccꢀUVLOꢀStartꢀThreshold 4.00 4.25 4.50
V
mV
V
♦
♦
♦
VccꢀUVLOꢀHysteresis
UVINꢀStartꢀThreshold
UVINꢀꢀHysteresis
ꢀ00 200
300
2.30 2.50 2.65
200 300
400
1.0
mV ♦
♦
UVINꢀInputꢀCurrent
UVIN=3.0V
µ
A
ERROR AMPLIFIER REFERENCE
2XꢀGainꢀConfig.,ꢀMeasureꢀ
fB;ꢀVcc=5V
ErrorꢀAmplifierꢀReference 0.792 0.800 0.808
V
V
ErrorꢀAmplifierꢀ
0.784 0.800 0.816
ReferenceꢀOverꢀLine
V
µ
♦
70
150
230
V
fB=0.9V,ꢀCOMP=0.9V
fB=0.9V,ꢀCOMP=0.9V
COMPꢀSinkꢀCurrent
ꢀCOMPꢀSourceꢀCurrent
VfBꢀInputꢀBiasꢀCurrent
ꢀCOMPꢀClamp
A
♦
♦
♦
-230 -150 -70
V
µ
A
50
200
nA
V
V
fB=0.8V
3.2
4.7
3.5
3.8
V
fB=0.7V,ꢀTA=25°C
ꢀCOMPꢀClampꢀTemp.ꢀꢀ
ꢀCoefficient
-2.0
mV/°C
VCC LINEAR REGULATOR
ViN = 6 to 23V,
ILOADꢀ=ꢀ0mAꢀtoꢀ30mA
5.0
5.3
♦
♦
VCCꢀOutputꢀVoltage
V
4.51 4.73
250 500
ViNꢀ=ꢀ5V,ꢀ20mA
Vin-Voutꢀ=ꢀDropoutꢀvoltageꢀwhenꢀ
Vccꢀregulatedꢀdropsꢀbyꢀ2%.ꢀꢀ
ꢀIVCCꢀ=ꢀ30ꢀmA.ꢀ
♦
DropoutꢀVoltage
750
mV
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
2
ELECTRICAL SPECIFICATIONS
SpecificationsꢀareꢀforꢀTAMB =ꢀTJ =ꢀ25°C,ꢀandꢀthoseꢀdenotedꢀbyꢀ♦ꢀapplyꢀoverꢀtheꢀfullꢀoperatingꢀrange,ꢀ-40°C<ꢀTj<ꢀ125°C.ꢀꢀUnlessꢀ
otherwiseꢀspecified:ꢀ4.5Vꢀ<ꢀVccꢀ<ꢀ5.5V,ꢀ3Vꢀ<ꢀViNꢀ<ꢀ22V,ꢀBSTꢀ=ꢀLXꢀ+ꢀ5V,ꢀUVINꢀ=ꢀ3V,ꢀCVCCꢀ=ꢀ1 F,ꢀCCOMPꢀ=ꢀ0.1 F,ꢀCssꢀ=ꢀ50nF.ꢀ
µ
µ
UNITS
PARAMETER
MIN TYP MAX
♦
CONDITIONS
CONTROL LOOP: PWM COMPARATOR, RAMP & LOOP DELAY PATH
RampꢀAmplitude
RAMPꢀOffset
0.80 1.00 1.20
V
V
♦
♦
1.7
2.0
2.3
RampꢀoffsetꢀTemperatureꢀ
Coefficient
-2
mV/°C
ns
GHꢀMinimumꢀPulseꢀWidth
150
97
180
♦
♦
MaximumꢀControllableꢀ
DutyꢀRatio
92
%
MaximumꢀDutyꢀRatio
InternalꢀOscillatorꢀRatio
TIMERS: SOFTSTART
SSꢀChargeꢀCurrent:
ꢀ00
%
Validꢀforꢀ20ꢀcycles
♦
♦
510 600
690
kHZ
-ꢀ6
-ꢀ0
-4.0
3.0
µ
A
♦
♦
FaultꢀPresent,ꢀ
SS=0.2V
SSꢀDischargeꢀCurrent:
1.0
2.0
mA
PROTECTION: SHORT CIRCUIT, OVERCURRENT & THERMAL
ShortꢀCircuitꢀThresholdꢀ
Voltage
0.2 0.25
0.3
ꢀ30
66
V
♦
♦
90
54
ꢀꢀ0
60
ms
mV
VfB=0.5V
HiccupꢀTimeout
OvercurrentꢀThresholdꢀ
Voltage
MeasuredꢀISPꢀ-ꢀISN
ISP,ꢀISNꢀCommonꢀModeꢀ
Range
0
3.6
V
ThermalꢀShutdownꢀ
Temperature
135 145
155
Guaranteedꢀbyꢀdesign
°C
ThermalꢀRecoveryꢀ
Temperature
ThermalꢀHysteresis
135
°C
°C
ꢀ0
OUTPUT: POWER STAGE
VGS=4.5V;ꢀ
IDrAiN=4.1A;ꢀꢀꢀꢀ
TAMB=25°C
35
75
75
mΩ
HighꢀSideꢀSwitchꢀRDSON
VGS=4.5V;ꢀ
IDrAiN=4.1A;ꢀꢀꢀꢀ
TAMB=25°C
SynchronousꢀLowꢀSideꢀ
SwitchꢀRDSON
35
mΩ
MaximumꢀOutputꢀ
Current
3
A
♦
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
3
CONTROLLER BLOCK DIAGRAM
C OMP
VC C
AS Y NC. S TAR TUP
COMP AR ATOR
SS
GL HOLD OFF
V FB INT
1.6 V
B S T
P W M LO O P
VFB
VC C
GmER R OR A MP LIFIE R
Gm
R E S E T
VC C
DOMINANT
GH
FAULT
10 uA
R
VPOS
S Y NCHR O NO US
QP WM
S OFTS TAR T INP UT
S S
Q
S WN
GL
0.1V
DR IV E R
P OS R E F
S
FAULT
FAULT
kHZ
600
P GND
R AMP =1V
C LK
CLOC K P ULS E GEN E R ATOR
FAULT
2.8 V
1.3 V
0.8V
R E FE R E NC E
C OR E
V CC
R E F OK
PO WE R
FAULT
THE R MAL
S HUTDOWN
S E T
DOMINANT
145ºC ON
135ºC OFF
S
4.25 V ON
4.05 V OFF
VC C UVLO
HICC UP FAULT
Q
0.25V
R
S HOR TC IR CUIT
DE TE C TION
VP OS
VFB INT
5V
GND
LINE AR
R E GULATOR
C LK
C OUNTER
C LR
200ms Delay
OV E R C UR R E NT
DE TE C TION
VIN
R E F OK
60 mV
140K
UV IN
IS N
IS P
2.50 V ON
2.20 V O FF
VIN UV LO
T HE R MAL AND O VE R C UR R E NT P R O T E CT IO N
50K
UV LO CO MP AR AT O R S
Note:ꢀTheꢀSP7661ꢀusesꢀtheꢀSipexꢀPWMꢀcontrollerꢀSP6136
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
4
PIN DESCRIPTION
SP7661
DFN PACKAGE
7mm x 4mm (Option 2)
26
25
24
23
22
21
P
P
P
1
2
3
LX
LX
LX
GND
GND
GND
BOTTOM VIEW
Heatsink Pad 1
Connect to Lx
P
4
5
LX
CC
GND
Pin 27
GND
V
6
7
UV
V
FB
IN
COMP
SS
20
19
18
17
GND
GND
Heatsink Pad 2
Connect to GND
8
9
GND
ISN
V
IN
Pin 28
10
BST
LX
Heatsink Pad 3
Connect to VINP
11
12
13
16
ISP
SWN
LX 15
14
Pin 29
LX
VINP
Pin
Pin # Name
Description
1-4
PGND Groundꢀconnectionꢀforꢀtheꢀsynchronousꢀrectifier.
GroundꢀPin.ꢀTheꢀcontrolꢀcircuitryꢀofꢀtheꢀICꢀandꢀlowerꢀpowerꢀdriverꢀareꢀreferencedꢀtoꢀthisꢀ
pin.ꢀReturnꢀseparatelyꢀfromꢀotherꢀgroundꢀtracesꢀtoꢀtheꢀ(-)ꢀterminalꢀofꢀCOut
5,ꢀ9,
ꢀ19,ꢀ20
GND
.
FeedbackꢀVoltageꢀandꢀShortꢀCircuitꢀDetectionꢀpin.ꢀItꢀisꢀtheꢀinvertingꢀinputꢀofꢀtheꢀ
Errorꢀ Amplifierꢀ andꢀ servesꢀ asꢀ theꢀ outputꢀ voltageꢀ feedbackꢀ pointꢀ forꢀ theꢀ Buckꢀ
6
VFB Converter.ꢀTheꢀoutputꢀvoltageꢀisꢀsensedꢀandꢀcanꢀbeꢀadjustedꢀthroughꢀanꢀexternalꢀ
resistorꢀdivider.ꢀꢀWheneverꢀVFBꢀdropsꢀ0.25Vꢀbelowꢀtheꢀpositiveꢀreference,ꢀaꢀshortꢀ
circuitꢀfaultꢀisꢀdetectedꢀandꢀtheꢀICꢀentersꢀhiccupꢀmode.
OutputꢀofꢀtheꢀErrorꢀAmplifier.ꢀItꢀisꢀinternallyꢀconnectedꢀtoꢀtheꢀinvertingꢀinputꢀofꢀtheꢀ
COMP PWMꢀcomparator.ꢀꢀAnꢀoptimalꢀfilterꢀcombinationꢀisꢀchosenꢀandꢀconnectedꢀtoꢀthisꢀ
pinꢀandꢀeitherꢀgroundꢀorꢀVFBꢀtoꢀstabilizeꢀtheꢀvoltageꢀmodeꢀloop.
7
SoftꢀStart.ꢀConnectꢀanꢀexternalꢀcapacitorꢀbetweenꢀSSꢀandꢀGNDꢀtoꢀsetꢀtheꢀsoftꢀstartꢀ
8
SS
rateꢀbasedꢀonꢀtheꢀ10µAꢀsourceꢀcurrent.ꢀTheꢀSSꢀpinꢀisꢀheldꢀlowꢀviaꢀaꢀ1mAꢀ(min)ꢀ
currentꢀduringꢀallꢀfaultꢀconditions.
ꢀ0
ꢀꢀ
ISN
ISP
Currentꢀsenseꢀnegativeꢀinput.ꢀRail-to-railꢀinputꢀforꢀovercurrentꢀdetection.
Currentꢀsenseꢀpositiveꢀinput.ꢀRail-to-railꢀinputꢀforꢀovercurrentꢀdetection.
LowerꢀsupplyꢀrailꢀforꢀtheꢀGHꢀhigh-sideꢀgateꢀdriver.ꢀConnectꢀthisꢀpinꢀtoꢀtheꢀswitchingꢀ
nodeꢀasꢀcloseꢀasꢀpossibleꢀtoꢀpinsꢀ23-ꢀ27.ꢀDoꢀnotꢀconnectꢀthisꢀpinꢀtoꢀpinsꢀ14ꢀ–ꢀ16.
ꢀ2
ꢀ3
SWN
VINP InputꢀconnectionꢀtoꢀtheꢀhighꢀsideꢀN-channelꢀMOSFET.ꢀ
14-16,ꢀ
23-26
LX
ConnectꢀanꢀinductorꢀbetweenꢀthisꢀpinꢀandꢀVOut.
Highꢀsideꢀdriverꢀsupplyꢀpin.ꢀꢀConnectꢀBSTꢀtoꢀtheꢀexternalꢀboostꢀdiodeꢀandꢀcapacitorꢀ
ꢀ7
BST asꢀ shownꢀ inꢀ theꢀTypicalꢀApplicationꢀ Circuitꢀ onꢀ pageꢀ 1.ꢀ ꢀTheꢀ highꢀ sideꢀ driverꢀ isꢀ
connectedꢀbetweenꢀBSTꢀpinꢀandꢀSWNꢀpin.ꢀ
18
2ꢀ
22
VIN
V
iNꢀconnectionꢀforꢀinternalꢀLDOꢀandꢀPWMꢀController.ꢀ
UVLOꢀinputꢀforꢀViNꢀvoltage.ꢀConnectꢀaꢀresistorꢀdividerꢀbetweenꢀViNꢀandꢀUVINꢀ
UVIN toꢀsetꢀminimumꢀoperatingꢀvoltage.ꢀꢀUseꢀresistorꢀvaluesꢀbelowꢀ20kΩꢀtoꢀoverrideꢀ
internalꢀresistorꢀdivider.ꢀꢀ
Outputꢀofꢀinternalꢀregulator.ꢀꢀMayꢀbeꢀexterinallyꢀbiasedꢀifꢀVinꢀ<ꢀ5V.
VCC
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
5
THEORY OF OPERATION
Soft Start
General Overview
“SoftꢀStart”ꢀisꢀachievedꢀwhenꢀaꢀpowerꢀcon-
verterꢀ rampsꢀ upꢀ theꢀ outputꢀ voltageꢀ whileꢀ
controllingꢀtheꢀmagnitudeꢀofꢀtheꢀinputꢀsup-
plyꢀsourceꢀcurrent.ꢀInꢀaꢀmodernꢀstepꢀdownꢀ
converter,ꢀrampingꢀupꢀtheꢀpositiveꢀterminalꢀ
ofꢀtheꢀerrorꢀamplifierꢀcontrolsꢀsoftꢀstart.ꢀAsꢀaꢀ
result,ꢀexcessꢀsourceꢀcurrentꢀcanꢀbeꢀdefinedꢀ
asꢀtheꢀcurrentꢀrequiredꢀtoꢀchargeꢀtheꢀoutputꢀ
capacitor.
Theꢀ SP7661ꢀ isꢀ aꢀ fixedꢀ frequency,ꢀ volt-
ageꢀ mode,ꢀ synchronousꢀ PWMꢀ regulatorꢀ
optimizedꢀforꢀhighꢀefficiency.ꢀTheꢀpartꢀhasꢀ
beenꢀspecificallyꢀdesignedꢀforꢀsingleꢀsupplyꢀ
operationꢀfromꢀaꢀ5Vꢀtoꢀ22Vꢀinput.
TheꢀheartꢀofꢀtheꢀSP7661ꢀisꢀaꢀwideꢀbandwidthꢀ
transconductanceꢀamplifierꢀdesignedꢀtoꢀac-
commodateꢀTypeꢀIIꢀandꢀTypeꢀIIIꢀcompensa-
tionꢀschemes.ꢀAꢀprecisionꢀ0.8Vꢀreference,ꢀ
presentꢀonꢀtheꢀpositiveꢀterminalꢀofꢀtheꢀerrorꢀ
amplifier,ꢀpermitsꢀtheꢀprogrammingꢀofꢀtheꢀ
outputꢀvoltageꢀdownꢀtoꢀ0.8VꢀviaꢀtheꢀVFBꢀ
pin.ꢀꢀTheꢀoutputꢀofꢀtheꢀerrorꢀamplifier,ꢀCOMP,ꢀ
isꢀcomparedꢀtoꢀaꢀ1.1Vꢀpeak-to-peakꢀramp,ꢀ
whichꢀisꢀresponsibleꢀforꢀtrailingꢀedgeꢀPWMꢀ
control.ꢀThisꢀvoltageꢀrampꢀandꢀPWMꢀcontrolꢀ
logicꢀareꢀgovernedꢀbyꢀtheꢀinternalꢀoscillatorꢀ
thatꢀaccuratelyꢀsetsꢀtheꢀPWMꢀfrequencyꢀtoꢀ
600kHz.
IViN = COutꢀ•ꢀ(∆VOutꢀ/ꢀ∆TSOft-StArt)
TheꢀSP7661ꢀprovidesꢀtheꢀuserꢀwithꢀtheꢀop-
tionꢀtoꢀprogramꢀtheꢀsoftꢀstartꢀrateꢀbyꢀtyingꢀ
aꢀcapacitorꢀfromꢀtheꢀSSꢀpinꢀtoꢀGND.ꢀTheꢀ
selectionꢀofꢀthisꢀcapacitorꢀisꢀbasedꢀonꢀtheꢀ
10µAꢀpullꢀupꢀcurrentꢀpresentꢀatꢀtheꢀSSꢀpinꢀ
andꢀtheꢀ0.8Vꢀreferenceꢀvoltage.ꢀTherefore,ꢀ
theꢀexcessꢀsourceꢀcanꢀbeꢀredefinedꢀas:
IViN = COut • [∆VOutꢀ•10µAꢀ/ꢀ(CSSꢀ•ꢀ0.8V)]
Under Voltage Lock Out (UVLO)
Theꢀ SP7661ꢀ containsꢀ twoꢀ uniqueꢀ controlꢀ
featuresꢀthatꢀareꢀveryꢀpowerfulꢀinꢀdistributedꢀ
applications.ꢀFirst,ꢀnonsynchronousꢀdriverꢀ
controlꢀisꢀenabledꢀduringꢀstartup,ꢀtoꢀprohibitꢀ
theꢀlowꢀsideꢀswitchꢀfromꢀpullingꢀdownꢀtheꢀ
outputꢀ untilꢀ theꢀ highꢀ sideꢀ switchꢀ hasꢀ at-
temptedꢀtoꢀturnꢀon.ꢀSecond,ꢀaꢀ100%ꢀdutyꢀ
cycleꢀtimeoutꢀensuresꢀthatꢀtheꢀꢀlowꢀsideꢀswitchꢀ
isꢀ periodicallyꢀ enhancedꢀ duringꢀ extendedꢀ
periodsꢀatꢀ100%ꢀdutyꢀcycle.ꢀThisꢀguaran-
teesꢀ theꢀ synchronizedꢀ refreshingꢀ ofꢀ theꢀ
BSTꢀcapacitorꢀduringꢀveryꢀlargeꢀdutyꢀratios.ꢀ
TheꢀSP7661ꢀhasꢀtwoꢀseparateꢀUVLOꢀcom-
paratorsꢀtoꢀmonitorꢀtheꢀbiasꢀ(Vcc)ꢀandꢀInputꢀ
(ViN)ꢀvoltagesꢀindependently.ꢀTheꢀVccꢀUVLOꢀ
isꢀinternallyꢀsetꢀtoꢀ4.25V.ꢀTheꢀViNꢀUVLOꢀisꢀ
programmableꢀ throughꢀ UViNꢀ pin.ꢀ Whenꢀ
UVINꢀpinꢀisꢀgreaterꢀthanꢀ2.5VꢀtheꢀSP7661ꢀ
isꢀpermittedꢀtoꢀstartꢀupꢀpendingꢀtheꢀremovalꢀ
ofꢀallꢀotherꢀfaults.ꢀAꢀpairꢀofꢀinternalꢀresistorsꢀ
isꢀconnectedꢀtoꢀUVINꢀasꢀshownꢀinꢀtheꢀfigureꢀ
below.ꢀ
SP7661
VIN
TheꢀSP7661ꢀalsoꢀcontainsꢀaꢀnumberꢀofꢀvalu-
ableꢀprotectionꢀfeatures.ꢀProgrammableꢀVIN
UVLOꢀallowsꢀtheꢀuserꢀtoꢀsetꢀtheꢀexactꢀvalueꢀ
atꢀwhichꢀtheꢀconversionꢀvoltageꢀcanꢀsafelyꢀ
beginꢀdown-conversion,ꢀandꢀanꢀinternalꢀVCC
UVLOꢀwhichꢀensuresꢀthatꢀtheꢀcontrollerꢀitselfꢀ
hasꢀ enoughꢀ voltageꢀ toꢀ properlyꢀ operate.ꢀ
Otherꢀ protectionꢀ featuresꢀ includeꢀ thermalꢀ
shutdownꢀandꢀshort-circuitꢀdetection.ꢀInꢀtheꢀ
eventꢀthatꢀeitherꢀaꢀthermal,ꢀshort-circuit,ꢀorꢀ
UVLOꢀfaultꢀisꢀdetected,ꢀtheꢀSP7661ꢀisꢀforcedꢀ
intoꢀanꢀidleꢀstateꢀwhereꢀtheꢀoutputꢀdriversꢀ
areꢀheldꢀoffꢀforꢀaꢀfiniteꢀperiodꢀbeforeꢀaꢀrestartꢀ
isꢀattempted.
R6
R7
140KΩ
UVIN
GND
+
-
2.5V ON
2.2V OFF
50KΩ
Internal and external bias of UVIN
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
6
THEORY OF OPERATION
ThereforeꢀwithoutꢀexternalꢀbiasingꢀtheꢀViN
startꢀthresholdꢀisꢀ9.5V.Aꢀsmallꢀcapacitorꢀmayꢀ
acrossꢀ theꢀ inductor.ꢀ Over-currentꢀ isꢀ de-
tectedꢀbyꢀmonitoringꢀaꢀdifferentialꢀvoltageꢀ
acrossꢀtheꢀoutputꢀinductorꢀasꢀshownꢀinꢀtheꢀ
nextꢀfigure.
beꢀrequiredꢀbetweenꢀUVINꢀandꢀGNDꢀtoꢀfilterꢀ
outꢀnoise.ꢀꢀForꢀapplicationsꢀwithꢀViNꢀofꢀ5Vꢀ
orꢀ3.3V,ꢀconnectꢀUVINꢀdirectlyꢀtoꢀViN.ꢀꢀToꢀ
programꢀtheꢀViN startꢀthreshold,ꢀꢀuseꢀaꢀpairꢀ
ofꢀexternalꢀresistorsꢀasꢀshown.ꢀIfꢀexternalꢀ
resistorsꢀareꢀanꢀorderꢀofꢀmagnitudeꢀsmallerꢀ
thanꢀinternalꢀresistors,ꢀꢀthenꢀtheꢀViNꢀstartꢀ
thresholdꢀisꢀgivenꢀby:
SP7661
Lꢀ=ꢀ2.7uH,ꢀDCRꢀ=ꢀ4.1mΩ
VOUT
SWN
R3
5.11KΩ
R4
5.11KΩ
ViN(start)ꢀ=ꢀ2.5ꢀ•ꢀ(R6+R7)/R7
Forꢀexample,ꢀꢀifꢀitꢀisꢀrequiredꢀtoꢀhaveꢀaꢀViN
startꢀthresholdꢀofꢀ7V,ꢀꢀthenꢀletꢀR7ꢀ=ꢀ5KΩꢀandꢀ
usingꢀtheꢀViN startꢀthresholdꢀequationꢀweꢀgetꢀ
R6ꢀ=ꢀ9.09KΩ.ꢀ
ISP
ISN
CSP
6.8nF
CS
0.1uF
Thermal and Short-Circuit Protection
BecauseꢀtheꢀSP7661ꢀisꢀdesignedꢀtoꢀdriveꢀ
largeꢀoutputꢀcurrent,ꢀthereꢀisꢀaꢀchanceꢀthatꢀ
theꢀpowerꢀconverterꢀwillꢀbecomeꢀtooꢀhot.ꢀ
Therefore,ꢀ anꢀ internalꢀ thermalꢀ shutdownꢀ
(145°C)ꢀhasꢀbeenꢀincludedꢀtoꢀpreventꢀtheꢀ
ICꢀ fromꢀ malfunctioningꢀ atꢀ extremeꢀ tem-
peratures.
Over-current detection circuit
Inputsꢀ toꢀ anꢀ over-currentꢀ detectionꢀ com-
parator,ꢀsetꢀtoꢀtriggerꢀatꢀ60ꢀmVꢀnominal,ꢀareꢀ
connectedꢀtoꢀtheꢀinductorꢀasꢀshown.ꢀꢀSinceꢀ
theꢀ averageꢀ voltageꢀ sensedꢀ byꢀ theꢀ com-
paratorꢀisꢀequalꢀtoꢀtheꢀproductꢀofꢀinductorꢀ
currentꢀandꢀinductorꢀDCꢀresistanceꢀ(DCR),ꢀ
thenꢀIMAxꢀ=ꢀ60mVꢀ/ꢀDCR.ꢀSolvingꢀthisꢀequa-
tionꢀforꢀtheꢀspecificꢀinductorꢀinꢀcircuitꢀ1,ꢀꢀIMAx
=ꢀ14.6A.ꢀWhenꢀIMAxꢀisꢀreached,ꢀaꢀ220ꢀmsꢀ
time-outꢀisꢀinitiated,ꢀduringꢀwhichꢀtopꢀandꢀ
bottomꢀdriversꢀareꢀturnedꢀoff.ꢀFollowingꢀtheꢀ
time-out,ꢀaꢀrestartꢀisꢀattempted.ꢀIfꢀtheꢀfaultꢀ
conditionꢀpersists,ꢀꢀthenꢀtheꢀtime-outꢀisꢀre-
peatedꢀ(referredꢀtoꢀasꢀhiccup).ꢀ
Aꢀ short-circuitꢀ detectionꢀ comparatorꢀ hasꢀ
alsoꢀbeenꢀincludedꢀinꢀtheꢀSP7661ꢀtoꢀprotectꢀ
againstꢀanꢀaccidentalꢀshortꢀatꢀtheꢀoutputꢀofꢀ
theꢀpowerꢀconverter.ꢀThisꢀcomparatorꢀcon-
stantlyꢀmonitorsꢀtheꢀpositiveꢀandꢀnegativeꢀ
terminalsꢀofꢀtheꢀerrorꢀamplifier,ꢀandꢀifꢀtheꢀVfB
pinꢀfallsꢀmoreꢀthanꢀ250mVꢀ(typical)ꢀbelowꢀ
theꢀpositiveꢀreference,ꢀaꢀshort-circuitꢀfaultꢀ
isꢀ set.ꢀ Becauseꢀ theꢀ SSꢀ pinꢀ overridesꢀ theꢀ
internalꢀ0.8Vꢀreferenceꢀduringꢀsoftꢀstart,ꢀtheꢀ
SP7661ꢀisꢀcapableꢀofꢀdetectingꢀshort-circuitꢀ
faultsꢀthroughoutꢀtheꢀdurationꢀofꢀsoftꢀstartꢀasꢀ
wellꢀasꢀinꢀregularꢀoperation.
Increasing the Current Limi
t
IfꢀꢀitꢀisꢀdesiredꢀtoꢀsetꢀIMAxꢀꢀ>ꢀ{60mVꢀ/ꢀDCR}ꢀ(inꢀ
thisꢀcaseꢀlargerꢀthanꢀ14.6A),ꢀthenꢀaꢀresistorꢀ
R9 shouldꢀbeꢀaddedꢀasꢀshownꢀinꢀtheꢀnextꢀ
figure.ꢀꢀꢀR9ꢀformsꢀaꢀresistorꢀdividerꢀandꢀre-
ducesꢀtheꢀvoltageꢀseenꢀbyꢀtheꢀcomparator.ꢀ
Over-Current Protection
Theꢀ Over-currentꢀ protectionꢀ featureꢀ canꢀ
onlyꢀbeꢀusedꢀonꢀoutputꢀvoltagesꢀ≤ꢀ3.3ꢀvolts.ꢀ
Itꢀ isꢀ limitedꢀ byꢀ theꢀ commonꢀ modeꢀ ratingꢀ
ofꢀtheꢀop-ampꢀusedꢀtoꢀsenseꢀtheꢀvoltageꢀ
(IMAx •ꢀꢀDCR)
R9ꢀꢀꢀ ꢀ{R3ꢀ+ꢀR4ꢀ+ꢀR9}ꢀꢀ
Since:ꢀꢀ60mV
=
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
7
THEORY OF OPERATION
SolvingꢀforꢀR9ꢀweꢀget:
R8ꢀ=ꢀ
ꢀꢀꢀ[60mVꢀ•ꢀ(R3ꢀ+ꢀR4)]ꢀꢀꢀꢀꢀꢀ
R9ꢀ=
R4 • [VOut -ꢀ60mVꢀ+ꢀ(IMAXꢀ• DCR)]
60mVꢀ-ꢀ(IMAX •ꢀDCR)
[(IMAx •ꢀDCR)ꢀ–ꢀ60mV]
Asꢀanꢀexample:ꢀifꢀdesiredꢀIMAxꢀisꢀ17A,ꢀthenꢀ
R9ꢀ=ꢀ63.4KΩ.
Asꢀanꢀexample:ꢀꢀforꢀIMAxꢀofꢀ4AꢀandꢀVOutꢀofꢀ3.3V,ꢀ
calculatedꢀR8ꢀisꢀ381kΩ.
SP7661
SP7661
Lꢀ=ꢀ2.7uH,ꢀDCRꢀ=ꢀ4.1mΩ
Lꢀ=ꢀ2.7uH,ꢀDCRꢀ=ꢀ4.1mΩ
VOUT
VOUT
SWN
SWN
R3
5.11KΩ
R4
5.11KΩ
R3
5.11KΩ
R4
5.11KΩ
R9
63.4KΩ
ISP
ISN
ISP
ISN
CSP
6.8nF
CSP
6.8nF
CS
0.1uF
R8
1.5MΩ
CS
0.1uF
Over-current detection circuit for
Over-current detection circuit for
Imax > 60mV / DCR
Imax < {60mV / DCR}
Decreasing the Current Limit
Handling of Faults
Uponꢀtheꢀdetectionꢀofꢀpowerꢀ(UVLO),ꢀther-
mal,ꢀorꢀshort-circuitꢀfaults,ꢀtheꢀSP7661ꢀisꢀ
forcedꢀintoꢀanꢀidleꢀstateꢀwhereꢀtheꢀSSꢀꢀandꢀ
COMPꢀpinsꢀareꢀpulledꢀlowꢀandꢀbothꢀswitchesꢀ
areꢀheldꢀoff.ꢀInꢀtheꢀeventꢀofꢀUVLOꢀfault,ꢀtheꢀ
SP7661ꢀremainsꢀinꢀthisꢀidleꢀstateꢀuntilꢀtheꢀ
UVLOꢀfaultꢀisꢀremoved.ꢀꢀUponꢀtheꢀdetectionꢀ
ofꢀaꢀthermalꢀorꢀshort-circuitꢀfault,ꢀanꢀinternalꢀ
100msꢀꢀtimerꢀisꢀactivated.ꢀInꢀtheꢀeventꢀofꢀaꢀ
short-circuitꢀfault,ꢀaꢀrestartꢀisꢀattemptedꢀim-
mediatelyꢀafterꢀtheꢀ100msꢀtimeoutꢀexpires.ꢀ
Whereas,ꢀwhenꢀaꢀthermalꢀfaultꢀisꢀdetectedꢀ
theꢀ100msꢀdelayꢀcontinuouslyꢀrecyclesꢀandꢀaꢀ
restartꢀcannotꢀbeꢀattemptedꢀuntilꢀtheꢀthermalꢀ
faultꢀisꢀremovedꢀandꢀtheꢀtimerꢀexpires.
IfꢀꢀitꢀisꢀrequiredꢀtoꢀsetꢀIMAxꢀ<ꢀ{60mVꢀ/ꢀDCR, a
resistorꢀisꢀaddedꢀasꢀshownꢀinꢀtheꢀfollowingꢀ
figure.ꢀR8ꢀincreasesꢀtheꢀnetꢀvoltageꢀdetectedꢀ
byꢀtheꢀcurrent-senseꢀcomparator.ꢀVoltageꢀatꢀ
theꢀpositiveꢀandꢀnegativeꢀterminalꢀofꢀcom-
paratorꢀisꢀgivenꢀby:
VSP = VOutꢀ+ꢀ(IMAx •ꢀDCR)
VSN = VOut • {R8ꢀ/ꢀ(R4ꢀ+R8)}
Sinceꢀtheꢀcomparatorꢀisꢀtriggeredꢀatꢀ60mV:
VSP-VSNꢀ=ꢀ60ꢀmV
Combiningꢀtheꢀaboveꢀequationsꢀandꢀsolv-
ingꢀforꢀR8:
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
8
APPLICATIONS INFORMATION
Error Amplifier and Voltage Loop
Theꢀsecondꢀfeatureꢀisꢀaꢀ100%ꢀdutyꢀcycleꢀ
timeoutꢀthatꢀensuresꢀsynchronizedꢀrefresh-
ingꢀofꢀtheꢀBSTꢀcapacitorꢀatꢀveryꢀhighꢀdutyꢀ
ratios.ꢀInꢀtheꢀeventꢀthatꢀtheꢀhighꢀsideꢀNFETꢀ
isꢀonꢀforꢀ20ꢀcontinuousꢀclockꢀcycles,ꢀaꢀresetꢀ
isꢀgivenꢀtoꢀtheꢀPWMꢀflipꢀflopꢀhalfꢀwayꢀthroughꢀ
TheꢀheartꢀofꢀtheꢀSP7661ꢀvoltageꢀerrorꢀloopꢀ
isꢀ aꢀ highꢀ performance,ꢀ wideꢀ bandwidth
transconductanceꢀ amplifier.ꢀ Becauseꢀ ofꢀ
theꢀꢀamplifier’sꢀcurrentꢀlimitedꢀꢀ(+/-150µA)ꢀ
transconductance,ꢀthereꢀareꢀmanyꢀwaysꢀtoꢀ
compensateꢀtheꢀvoltageꢀloopꢀorꢀtoꢀcontrolꢀtheꢀ
COMPꢀpinꢀexternally.ꢀꢀIfꢀaꢀsimple,ꢀsingle-pole,ꢀ
single-zeroꢀresponseꢀisꢀdesired,ꢀthenꢀcom-
pensationꢀcanꢀbeꢀasꢀsimpleꢀasꢀanꢀRCꢀcircuitꢀ
toꢀGround.ꢀIfꢀaꢀmoreꢀcomplexꢀcompensationꢀ
isꢀrequired,ꢀthenꢀtheꢀamplifierꢀhasꢀenoughꢀ
bandwidthꢀ(45°ꢀatꢀ4ꢀMHz),ꢀandꢀenoughꢀgainꢀ
(60dB)ꢀtoꢀrunꢀTypeꢀIIIꢀcompensationꢀschemesꢀ
withꢀadequateꢀgainꢀandꢀphaseꢀmarginsꢀatꢀ
crossoverꢀfrequenciesꢀgreaterꢀthanꢀ50kHz.ꢀ
st
theꢀ21 ꢀcycle.ꢀThisꢀforcesꢀGLꢀtoꢀriseꢀforꢀꢀtheꢀ
cycle,ꢀinꢀturnꢀrefreshingꢀtheꢀBSTꢀcapacitor.ꢀ
Theꢀboostꢀcapacitorꢀisꢀusedꢀtoꢀgenerateꢀaꢀ
highꢀvoltageꢀdriveꢀsupplyꢀforꢀtheꢀhighꢀsideꢀ
switch,ꢀwhichꢀisꢀVccꢀaboveꢀViN.
Power MOSFETs
TheꢀSP7661ꢀcontainsꢀaꢀpairꢀofꢀintegratedꢀlowꢀ
resistanceꢀN-channelꢀswitchesꢀdesignedꢀtoꢀ
driveꢀupꢀtoꢀ3Aꢀofꢀoutputꢀcurrent.ꢀCareꢀshouldꢀ
beꢀtakenꢀtoꢀde-rateꢀtheꢀoutputꢀcurrentꢀbasedꢀ
onꢀtheꢀthermalꢀconditionsꢀinꢀtheꢀsystemꢀsuchꢀ
asꢀambientꢀtemperature,ꢀairflowꢀandꢀheatꢀ
sinking.ꢀMaximumꢀoutputꢀcurrentꢀcouldꢀbeꢀ
limitedꢀbyꢀthermalꢀlimitationsꢀofꢀaꢀparticularꢀ
applicationꢀbyꢀtakingꢀadvantageꢀofꢀtheꢀinte-
grated-over-temperatureꢀprotectiveꢀschemeꢀ
employedꢀinꢀtheꢀSP7661.ꢀꢀTheꢀSP7661ꢀincor-
poratesꢀaꢀbuilt-inꢀovertemperature protection
toꢀpreventꢀinternalꢀoverheating.
Theꢀcommonꢀmodeꢀoutputꢀofꢀtheꢀerrorꢀam-
plifierꢀꢀisꢀ0.9Vꢀtoꢀ2.2V.ꢀTherefore,ꢀtheꢀPWMꢀ
voltageꢀrampꢀhasꢀbeenꢀsetꢀbetweenꢀ1.1Vꢀandꢀ
2.2Vꢀtoꢀensureꢀproperꢀ0%ꢀtoꢀ100%ꢀdutyꢀcycleꢀ
capability.ꢀTheꢀ voltageꢀ loopꢀ alsoꢀ includesꢀ
twoꢀotherꢀveryꢀimportantꢀfeatures.ꢀOneꢀisꢀaꢀ
nonsynchronousꢀstartupꢀmode.ꢀBasically,ꢀtheꢀ
synchronousꢀrectifierꢀcannotꢀturnꢀonꢀunlessꢀ
theꢀhighꢀsideꢀswitchꢀhasꢀattemptedꢀtoꢀturnꢀ
onꢀorꢀtheꢀSSꢀpinꢀhasꢀexceededꢀ1.7V.ꢀThisꢀ
featureꢀpreventsꢀtheꢀcontrollerꢀfromꢀ“draggingꢀ
down”ꢀtheꢀoutputꢀvoltageꢀduringꢀstartupꢀorꢀ
inꢀfaultꢀmodes.ꢀ
Setting Output Voltages
TheꢀSP7661ꢀcanꢀbeꢀsetꢀtoꢀdifferentꢀoutputꢀ
voltages.ꢀTheꢀrelationshipꢀinꢀtheꢀfollowingꢀ
formulaꢀisꢀbasedꢀonꢀaꢀvoltageꢀdividerꢀfromꢀ
theꢀoutputꢀtoꢀtheꢀfeedbackꢀpinꢀVfB,ꢀwhichꢀisꢀ
setꢀtoꢀanꢀinternalꢀreferenceꢀvoltageꢀofꢀ0.80V.ꢀ
Standardꢀ1%ꢀmetalꢀfilmꢀresistorsꢀofꢀsurfaceꢀ
mountꢀsizeꢀ0603ꢀareꢀrecommended.
V
BST
GH
Voltage
V
SWN
V(V
CC)
GL
Voltage
VOutꢀ=ꢀꢀ0.80Vꢀ[R1ꢀ/ꢀR2ꢀ+ꢀ1ꢀ] =>
ꢀR2ꢀ=ꢀR1ꢀ/ꢀ[ (ꢀVOutꢀ/ꢀ0.80Vꢀ)ꢀ–ꢀ1ꢀ]
0V
V(V
)
IN
SWN
Voltage
ꢀWhereꢀR1ꢀ=ꢀ10KΩꢀandꢀforꢀVOutꢀ=ꢀ0.80Vꢀ
setting,ꢀsimplyꢀremoveꢀR2ꢀfromꢀtheꢀboard.ꢀ
Furthermore,ꢀoneꢀcouldꢀselectꢀtheꢀvalueꢀofꢀ
theꢀR1ꢀandꢀR2ꢀcombinationꢀtoꢀmeetꢀtheꢀexactꢀ
outputꢀvoltageꢀsettingꢀbyꢀrestrictingꢀtheꢀR1ꢀ
resistanceꢀrangeꢀsuchꢀthatꢀ10KΩꢀ<ꢀR1ꢀ<ꢀ
100KΩꢀforꢀoverallꢀsystemꢀloopꢀstability.ꢀꢀ
-0V
-V(Diode) V
V(V )+V(V
)
IN
CC
BST
Voltage
V(V
)
CC
TIME
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
9
APPLICATIONS INFORMATION
andꢀprovideꢀlowꢀcoreꢀlossꢀatꢀtheꢀhighꢀ
switchingꢀfrequency.ꢀꢀLowꢀcostꢀpowdered-
ironꢀcoresꢀhaveꢀaꢀgradualꢀsaturationꢀchar-
acteristicꢀbutꢀcanꢀintroduceꢀconsiderableꢀ
ACꢀcoreꢀloss,ꢀespeciallyꢀwhenꢀtheꢀinduc-
torꢀvalueꢀisꢀrelativelyꢀlowꢀandꢀtheꢀrippleꢀ
currentꢀisꢀhigh.ꢀFerriteꢀmaterials,ꢀalthoughꢀ
moreꢀexpensive,ꢀꢀhaveꢀanꢀabruptꢀsatura-
tionꢀcharacteristicꢀwithꢀtheꢀinductanceꢀ
droppingꢀsharplyꢀwhenꢀtheꢀpeakꢀdesignꢀ
currentꢀisꢀexceeded.ꢀNevertheless,ꢀtheyꢀ
areꢀpreferredꢀatꢀhighꢀswitchingꢀfrequen-
ciesꢀbecauseꢀtheyꢀpresentꢀveryꢀlowꢀcoreꢀ
lossꢀwhileꢀtheꢀdesignerꢀisꢀonlyꢀrequiredꢀ
to preventꢀsaturation.ꢀInꢀgeneral,ꢀferriteꢀ
orꢀmolypermalloyꢀmaterialsꢀareꢀaꢀbetterꢀ
choiceꢀforꢀallꢀbutꢀtheꢀmostꢀcostꢀsensitiveꢀ
applications.
Inductor Selection
Thereꢀareꢀmanyꢀfactorsꢀtoꢀconsiderꢀinꢀse-
lectingꢀtheꢀinductorꢀincludingꢀcoreꢀmaterial,ꢀ
inductanceꢀvs.ꢀfrequency,ꢀcurrentꢀhandlingꢀ
capability,ꢀefficiency,ꢀsizeꢀandꢀEMI.ꢀInꢀaꢀtypi-
calꢀSP7661ꢀcircuit,ꢀtheꢀinductorꢀisꢀchosenꢀ
primarilyꢀforꢀvalue,ꢀsaturationꢀcurrentꢀandꢀDCꢀ
resistance.ꢀIncreasingꢀtheꢀinductorꢀvalueꢀwillꢀ
decreaseꢀoutputꢀvoltageꢀripple,ꢀbutꢀdegradeꢀ
transientꢀresponse.ꢀLowꢀinductorꢀvaluesꢀpro-
videꢀtheꢀsmallestꢀsize,ꢀbutꢀcauseꢀlargeꢀrippleꢀ
currents,ꢀpoorꢀefficiencyꢀandꢀrequireꢀmoreꢀ
outputꢀcapacitanceꢀtoꢀsmoothꢀoutꢀtheꢀlargerꢀ
rippleꢀ current.ꢀTheꢀ inductorꢀ mustꢀ beꢀ ableꢀ
toꢀhandleꢀtheꢀpeakꢀcurrentꢀatꢀtheꢀswitchingꢀ
frequencyꢀwithoutꢀsaturating,ꢀandꢀtheꢀcopperꢀ
resistanceꢀinꢀtheꢀwindingꢀshouldꢀbeꢀkeptꢀasꢀ
lowꢀasꢀpossibleꢀtoꢀminimizeꢀresistiveꢀpowerꢀ
loss.ꢀAꢀgoodꢀcompromiseꢀbetweenꢀsize,ꢀlossꢀ
andꢀcostꢀisꢀtoꢀsetꢀtheꢀinductorꢀrippleꢀcurrentꢀ
toꢀbeꢀwithinꢀ20%ꢀtoꢀ40%ꢀofꢀtheꢀmaximumꢀ
outputꢀcurrent.
Optimizing Efficiency
Theꢀpowerꢀdissipatedꢀinꢀtheꢀinductorꢀisꢀequalꢀ
toꢀtheꢀsumꢀofꢀtheꢀcoreꢀandꢀcopperꢀlosses.ꢀ
Toꢀ minimizeꢀ copperꢀ losses,ꢀ theꢀ windingꢀ
resistanceꢀneedsꢀtoꢀbeꢀminimized,ꢀbutꢀthisꢀ
usuallyꢀcomesꢀatꢀtheꢀexpenseꢀofꢀaꢀlargerꢀ
inductor.ꢀCoreꢀlossesꢀhaveꢀaꢀmoreꢀsignificantꢀ
contributionꢀatꢀlowꢀoutputꢀcurrentꢀwhereꢀtheꢀ
copperꢀlossesꢀareꢀatꢀaꢀminimum,ꢀandꢀcanꢀ
typicallyꢀbeꢀneglectedꢀatꢀhigherꢀoutputꢀcur-
rentsꢀ whereꢀ theꢀ copperꢀ lossesꢀ dominate.ꢀ
Coreꢀ lossꢀ informationꢀ isꢀ usuallyꢀ availableꢀ
fromꢀtheꢀmagneticsꢀvendor.ꢀProperꢀinduc-
torꢀselectionꢀcanꢀaffectꢀtheꢀresultingꢀpowerꢀ
supplyꢀefficiencyꢀbyꢀmoreꢀthanꢀ15%!
Theꢀswitchingꢀfrequencyꢀandꢀtheꢀinductorꢀ
operatingꢀpointꢀdetermineꢀtheꢀinductorꢀvalueꢀ
asꢀfollows:
.
VOutꢀꢀ•ꢀ(ViN(MAx) - VOut)ꢀꢀꢀ
Lꢀꢀꢀꢀꢀ=
ƒ
ViN(MAx) • sꢀ•ꢀKr • IOut(MAx)
where:
ƒ
sꢀꢀ=ꢀswitchingꢀfrequency
ꢀKrꢀꢀ=ꢀratioꢀofꢀtheꢀACꢀinductorꢀrippleꢀcurrentꢀ
toꢀtheꢀmaximumꢀoutputꢀcurrent
Theꢀcopperꢀlossꢀinꢀtheꢀinductorꢀcanꢀbeꢀcal-
culatedꢀusingꢀtheꢀfollowingꢀequation:
Theꢀpeak-to-peakꢀinductorꢀrippleꢀcurrentꢀis:
.
VOutꢀ•ꢀ(ViN(MAx) - VOut)
=
IPP
PL(Cu) = I2L(rMS) • rwiNDiNg
whereꢀIL(rMS)ꢀisꢀtheꢀRMSꢀinductorꢀcurrentꢀ
thatꢀcanꢀbeꢀcalculatedꢀasꢀfollows:
ƒ
ViN(MAx) • sꢀ•L
Onceꢀtheꢀrequiredꢀinductorꢀvalueꢀisꢀselected,ꢀ
theꢀproperꢀselectionꢀofꢀcoreꢀmaterialꢀisꢀbasedꢀ
onꢀpeakꢀinductorꢀcurrentꢀandꢀefficiencyꢀre-
quirements.ꢀTheꢀcoreꢀmustꢀbeꢀlargeꢀenoughꢀ
notꢀtoꢀsaturateꢀatꢀtheꢀpeakꢀinductorꢀcurrentꢀ
2
.
I
PP
IL(rMS) = IOut(MAx) •
ꢀ
3
ꢀ +
(
)
I
Out(MAx)
√ꢀ
IPP
ꢀ
I
PeAk = IOut(MAx)
+
2
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ0
APPLICATIONS INFORMATION
2 +ꢀ(IPP •ReSr)2
Output Capacitor Selection
PP •ꢀ(1ꢀ–ꢀD)
I
ꢀ∆VOut =
(
)
ƒ
sꢀ•ꢀCOut
TheꢀrequiredꢀESRꢀ(EquivalentꢀSeriesꢀRe-
sistance)ꢀandꢀcapacitanceꢀdriveꢀtheꢀselec-
tionꢀofꢀtheꢀtypeꢀandꢀquantityꢀofꢀtheꢀoutputꢀ
capacitors.ꢀTheꢀESRꢀmustꢀbeꢀsmallꢀenoughꢀ
thatꢀbothꢀtheꢀresistiveꢀvoltageꢀdeviationꢀdueꢀ
toꢀaꢀstepꢀchangeꢀinꢀtheꢀloadꢀcurrentꢀandꢀ
theꢀ outputꢀ rippleꢀ voltageꢀ doꢀ notꢀ exceedꢀ
theꢀtoleranceꢀlimitsꢀexpectedꢀonꢀtheꢀoutputꢀ
voltage.ꢀ Duringꢀ anꢀ outputꢀ loadꢀ transient,ꢀ
theꢀoutputꢀcapacitorꢀmustꢀsupplyꢀallꢀtheꢀad-
ditionalꢀcurrentꢀdemandedꢀbyꢀtheꢀloadꢀuntilꢀ
theꢀSP7661ꢀadjustsꢀtheꢀinductorꢀcurrentꢀtoꢀ
theꢀnewꢀvalue.
√ꢀ
ƒ
sꢀ=ꢀSwitchingꢀFrequency
Dꢀ=ꢀDutyꢀCycle
COut = Output Capacitance Value
Input Capacitor Selection
Theꢀinputꢀcapacitorꢀshouldꢀbeꢀselectedꢀforꢀ
ripple current rating, capacitance and volt-
ageꢀrating.ꢀTheꢀinputꢀcapacitorꢀmustꢀmeetꢀ
theꢀrippleꢀcurrentꢀrequirementꢀimposedꢀ
byꢀtheꢀswitchingꢀcurrent.ꢀInꢀcontinuousꢀ
conductionꢀmode,ꢀtheꢀsourceꢀcurrentꢀofꢀ
theꢀhigh-sideꢀMOSFETꢀisꢀapproximatelyꢀaꢀ
squareꢀwaveꢀofꢀdutyꢀcycleꢀVOut/ViN.ꢀMoreꢀ
accurately,ꢀtheꢀcurrentꢀwaveꢀformꢀisꢀtrap-
ezoidal,ꢀgivenꢀaꢀfiniteꢀturn-onꢀandꢀturn-off,ꢀ
switchꢀtransitionꢀslope.ꢀMostꢀofꢀthisꢀcurrentꢀ
isꢀsuppliedꢀbyꢀtheꢀinputꢀbypassꢀcapaci-
tors.ꢀTheꢀRMSꢀcurrentꢀhandlingꢀcapabilityꢀ
ofꢀtheꢀinputꢀcapacitorsꢀisꢀdeterminedꢀatꢀꢀ
maximumꢀoutputꢀcurrentꢀandꢀunderꢀtheꢀ
assumptionꢀthatꢀtheꢀpeak-to-peakꢀinductorꢀ
rippleꢀcurrentꢀisꢀlow,ꢀitꢀisꢀgivenꢀby:
InꢀorderꢀtoꢀmaintainꢀVOut,theꢀcapacitanceꢀ
mustꢀbeꢀlargeꢀenoughꢀsoꢀthatꢀtheꢀoutputꢀ
voltageꢀisꢀheldꢀupꢀwhileꢀtheꢀinductorꢀcur-
rentꢀ rampsꢀ toꢀ theꢀ valueꢀ correspondingꢀ
toꢀ theꢀ newꢀ loadꢀ current.ꢀAdditionally,ꢀ theꢀ
ESRꢀinꢀtheꢀoutputꢀcapacitorꢀcausesꢀaꢀstepꢀ
inꢀtheꢀoutputꢀvoltageꢀequalꢀtoꢀtheꢀcurrent.ꢀ
Becauseꢀofꢀtheꢀfastꢀtransientꢀresponseꢀandꢀ
inherentꢀ100%ꢀtoꢀ0%ꢀdutyꢀcycleꢀcapabilityꢀ
providedꢀbyꢀtheꢀSP7661ꢀwhenꢀexposedꢀtoꢀ
outputꢀloadꢀtransients,ꢀtheꢀoutputꢀcapacitorꢀ
isꢀtypicallyꢀchosenꢀforꢀESR,ꢀnotꢀforꢀcapaci-
tanceꢀvalue.
TheꢀESRꢀofꢀtheꢀoutputꢀcapacitor,ꢀcombinedꢀ
withꢀtheꢀinductorꢀrippleꢀcurrent,ꢀisꢀtypicallyꢀ
theꢀmainꢀcontributorꢀtoꢀoutputꢀvoltageꢀripple.ꢀ
TheꢀmaximumꢀallowableꢀESRꢀrequiredꢀtoꢀ
maintainꢀaꢀspecifiedꢀoutputꢀvoltageꢀrippleꢀcanꢀ
I
CiN(rMS) = IOut(MAx) • D(1 - D)
√
Theꢀworstꢀcaseꢀoccursꢀwhenꢀtheꢀdutyꢀcycleꢀ
Dꢀisꢀ50%ꢀandꢀgivesꢀanꢀRMSꢀcurrentꢀvalueꢀ
equalꢀtoꢀIOUT/2.ꢀꢀSelectꢀinputꢀcapacitorsꢀwithꢀ
adequateꢀrippleꢀcurrentꢀratingꢀtoꢀensureꢀreli-
ableꢀoperation.
beꢀcalculatedꢀby
:
∆VOut
ReSr ≤
IPk-Pk
Theꢀpowerꢀdissipatedꢀinꢀtheꢀinputꢀcapaci-
torꢀis:
where:
∆VOut = Peak-to-Peak Output Voltage Ripple
Pk = Peak-to-Peak Inductor Ripple Current
PCiN = I2CiN(rMS) • reSr(CiN)
IPk-
Thisꢀcanꢀbecomeꢀaꢀsignificantꢀpartꢀofꢀpowerꢀ
lossesꢀinꢀaꢀconverterꢀandꢀhurtꢀtheꢀoverallꢀ
energyꢀ transferꢀ efficiency.ꢀ Theꢀ inputꢀ volt-
ageꢀrippleꢀprimarilyꢀdependsꢀonꢀtheꢀinputꢀ
Theꢀtotalꢀoutputꢀrippleꢀisꢀaꢀcombinationꢀofꢀ
theꢀESRꢀandꢀtheꢀoutputꢀcapacitanceꢀvalueꢀ
andꢀcanꢀbeꢀcalculatedꢀasꢀfollows:
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀꢀ
APPLICATIONS INFORMATION
Loop Compensation Design
capacitorꢀ ESRꢀ andꢀ capacitance.ꢀ Ignoringꢀ
theꢀinductorꢀrippleꢀcurrent,ꢀtheꢀinputꢀvoltageꢀ
rippleꢀcanꢀbeꢀdeterminedꢀby:
Theꢀopenꢀloopꢀgainꢀofꢀtheꢀwholeꢀsystemꢀcanꢀ
beꢀdividedꢀintoꢀtheꢀgainꢀofꢀtheꢀerrorꢀampli-
fier,ꢀPWMꢀmodulator,ꢀbuckꢀconverterꢀoutputꢀ
stage,ꢀandꢀfeedbackꢀresistorꢀdivider.ꢀInꢀorderꢀ
toꢀcrossꢀoverꢀatꢀtheꢀdesiredꢀfrequencyꢀcut-offꢀ
(FCO),ꢀtheꢀgainꢀofꢀtheꢀerrorꢀamplifierꢀmustꢀ
compensateꢀforꢀtheꢀattenuationꢀcausedꢀbyꢀ
theꢀrestꢀofꢀtheꢀloopꢀatꢀthisꢀfrequency.ꢀTheꢀ
goalꢀ ofꢀ loopꢀ compensationꢀ isꢀ toꢀ manipu-
lateꢀloopꢀfrequencyꢀresponseꢀsuchꢀthatꢀitsꢀ
crossoverꢀgainꢀatꢀ0db,ꢀresultsꢀinꢀaꢀslopeꢀofꢀ
-20db/decade.ꢀ
∆ViN =
I
Out(MAx)•reSr(CiN) +
I
Out(MAx)•VOut•(ViN - VOut)
2
ƒ
V iN • sꢀ•ꢀCiN
Theꢀcapacitorꢀtypeꢀsuitableꢀforꢀtheꢀoutputꢀ
capacitorsꢀcanꢀalsoꢀbeꢀusedꢀforꢀtheꢀinputꢀ
capacitors.ꢀꢀHowever,ꢀexerciseꢀextraꢀcautionꢀ
whenꢀtantalumꢀcapacitorsꢀareꢀused.ꢀTantalumꢀ
capacitorsꢀareꢀknownꢀforꢀcatastrophicꢀfailureꢀ
whenꢀexposedꢀtoꢀsurgeꢀcurrent,ꢀandꢀinputꢀ
capacitorsꢀareꢀproneꢀtoꢀsuchꢀsurgeꢀcurrentꢀ
whenꢀpowerꢀsuppliesꢀareꢀconnectedꢀ“live”ꢀ
toꢀlowꢀimpedanceꢀpowerꢀsources.ꢀAlthoughꢀ
tantalumꢀcapacitorsꢀhaveꢀbeenꢀsuccessfullyꢀ
employedꢀ atꢀ theꢀ input,ꢀ itꢀ isꢀ generallyꢀ notꢀ
recommended.
Theꢀ firstꢀ stepꢀ ofꢀ compensationꢀ designꢀ isꢀ
toꢀpickꢀtheꢀloopꢀcrossoverꢀfrequency.ꢀHighꢀ
crossoverꢀ frequencyꢀ isꢀ desirableꢀ forꢀ fastꢀ
transientꢀresponse,ꢀbutꢀoftenꢀjeopardizesꢀtheꢀ
powerꢀsupplyꢀstability.ꢀCrossoverꢀfrequencyꢀ
shouldꢀ beꢀ higherꢀ thanꢀ theꢀ ESRꢀ zeroꢀ butꢀ
lessꢀthanꢀ1/5ꢀofꢀtheꢀswitchingꢀfrequencyꢀorꢀ
Type III Voltage Loop
Compensation
GAMP (s) Gain Block
PWM Stage
GPWM Gain
Block
Output Stage
GOUT (s) Gain
Block
VIN
(SRz2Cz2+1)(SR1Cz3+1)
(SRESRCOUT+ 1)
VREF
(Volts)
VOUT
VRAMP_PP
SR1Cz2(SRz3Cz3+1)(SRz2Cp1+1)
[S^2LCOUT+S(RESR+RDC) COUT+1]
(Volts)
Notes:
RESR = Output Capacitor Equivalent Series Resistance.
RDC = Output Inductor DC Resistance.
VRAMP_PP = SP7662 Internal Ramp Amplitude Peak-to-Peak Voltage.
Voltage Feedback
GFBK Gain Block
Condition:
Cz2 >> Cp1 & R1 >> Rz3
Output Load Resistance >> RESR & RDC
R2
VREF
or
VOUT
(R1 R2)
+
VFBK
SP7661 Voltage Mode Control Loop with Loop Dynamic
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ2
APPLICATIONS INFORMATION
.
ꢀ
120kHz.ꢀTheꢀESRꢀzeroꢀisꢀcontributedꢀbyꢀtheꢀ
ESRꢀassociatedꢀwithꢀtheꢀoutputꢀcapacitorsꢀ
andꢀcanꢀbeꢀdeterminedꢀby:
ƒP(LC)
=
2πꢀ• ꢀLꢀ• COut
√
ꢀ
WhenꢀtheꢀoutputꢀcapacitorsꢀareꢀofꢀaꢀCeramicꢀ
Type,ꢀtheꢀSP7661ꢀEvaluationꢀBoardꢀrequiresꢀ
aꢀTypeꢀIIIꢀcompensationꢀcircuitꢀtoꢀgiveꢀaꢀphaseꢀ
boostꢀofꢀ180°ꢀinꢀorderꢀtoꢀcounteractꢀtheꢀeffectsꢀ
ofꢀanꢀunderdampedꢀresonanceꢀofꢀtheꢀoutputꢀ
filterꢀatꢀtheꢀdoubleꢀpoleꢀfrequency.
ƒꢁ(ESR)
=
2πꢀ• COut • ReSr
Theꢀnextꢀstepꢀisꢀtoꢀcalculateꢀtheꢀcomplexꢀ
conjugateꢀ polesꢀ contributedꢀ byꢀ theꢀ LCꢀ
outputꢀfilter,
Gain
(dB)
Error Amplifier
Gain Bandwidth Product
Condition:
C22 >> CP1, R1 >> RZ3
20 Log (RZ2/R1)
Frequency
(Hz)
Bode Plot of Type III Error Amplifier Compensation.
CP1
CZ3
RZ2
RZ3
CZ2
OUT
V
V
FB
-
COMP
R1
+
68.1kΩ, 1%
R
SET
CF1
+
0.8V
-
54.48
(VOUT -0.8)
SET
R
=
(kΩ)
Type III Error Amplifier Compensation Circuit
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ3
APPLICATIONS INFORMATION
VOUT
L1,Wurth -744311220
2.2uH, 14 mOhm, 7x7mm, 9A
3.30V, 0-3A
LX
1
3
R3
5.11K
R4
5.11K
R11
0 Ohm
C4 47nF
C5
C7
NP
C6
NP
1
2
26
25
24
23
22
21
20
19
18
17
16
15
14
PGND
PGND
PGND
PGND
GND
VFB
LX
LX
100uF
R9
61.9k
ISN
ISP
RZ3
400
3
1
4
RZ2
CZ2
U1
LX
R1
10k
4
CVCC
4.7uF
SP7661
LX
4.02k
6800pF
CP1
R12
NP
GND
5
VCC
UVIN
CZ3
56pF
6
1500pF
7
COMP
SS
GND
GND
VIN
BST
LX
R7
NP
C8
NP
CSS
47nF
R14
NP
R2
CF1
8
100pF
R6
NP
3160
9
GND
ISN
R8 NP
10
11
12
13
RBST
ISP
0 Ohm
SD101AWS
DBST
C9 6.8nF
SWN
VIN
LX
22nF
CBST
LX
ISN
ISP
LX
LX
Rs2
Cs2
Rs1
Cs1
NP
VIN
1
12V (9.6V-22V)
NP
1 Ohm
2.2nF
1
C3
NP
C2
22uF
C1
22uF
1
2
GND
Evaluation Board Schematic
Parts shown for 9.6V-22V input, 3.3V Output
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
14
TYPICAL PERFORMANCE CHARACTERISTICS
IN
IN
Efficiency vs Load at 12V
Efficiency vs. Load at 22V
ꢀ00
90
80
70
60
50
40
ꢀ00
90
80
70
60
50
40
Vout=5.0V
Vout=3.3V
Vout=2.5V
Vout=1.8V
Vout=1.5V
Vout=1.2V
Vout=5.0V
Vout=3.3V
Vout=2.5V
Vout=1.8V
0.5
1.0
1.5
2.0
2.5
3.0
0.5
1.0
1.5
2.0
2.5
3.0
Output Load (A)
Output Load (A)
IN
Efficiency vs. Load at 3.3V
IN
Efficiency vs. Load at 5.0V
ꢀ00
95
90
85
80
75
70
ꢀ00
95
90
85
80
75
70
Vout=3.3V
Vout=2.5V
Vout=1.8V
Vout=1.5V
Vout=1.2V
Vout=0.8V
Vout=2.5V
Vout=1.8V
Vout=1.5V
Vout=1.2V
Vout=0.8V
0.5
1.0
1.5
2.0
2.5
3.0
ꢀ
ꢀ
2
2
3
3
Output Load (A)
Output Load (A)
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
15
TYPICAL PERFORMANCE CHARACTERISTICS
TransientꢀResponse:ꢀ
CH1:ꢀVOut. ꢀCH4:ꢀIOutꢀ1A/div.
TransientꢀResponse:ꢀCH1:ꢀVOut.ꢀꢀCH4:ꢀ
IOutꢀ1A/div.ꢀꢀꢁoomꢀshowingꢀ~1.5A/usꢀIrate
TransientꢀResponse:ꢀ
CH1:ꢀVOut. ꢀCH4:ꢀIOutꢀ1A/div.
ShortꢀCircuitꢀProtection:ꢀCH1:VOut.
ꢀCH2:Sstart.ꢀꢀCH4:IOut(10A/div).
ShortꢀCircuitꢀProtection:ꢀCH1:VOut.
CH2:Sstart.ꢀꢀCH4:ꢀInputꢀCurrentꢀ(5A/div).
ShortꢀCircuitꢀProtection:ꢀCH1:VOut.ꢀCH2:
Sstart.ꢀCH4:InputꢀCurrentꢀ(5A/div).
ꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀꢀ104msꢀrestartꢀrateꢀshown.ꢀ
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ6
TYPICAL PERFORMANCE CHARACTERISTICS
Start-upꢀinꢀtoꢀ3AꢀLoad:ꢀꢀꢀCH1:VOut.
CH2:SS.ꢀꢀCH3:ViN. ꢀCH4:ꢀIoutꢀ(2A/div).
CurrentꢀLimit:ꢀCH1:ꢀVOut. ꢀCH2:SoftStart.ꢀ
CH4ꢀIOutꢀ(2A/div).ꢀꢀCurrentꢀisꢀreachingꢀ
approximtelyꢀ6Aꢀbeforeꢀaꢀ
shutdownꢀ&ꢀrestart
CurrentꢀLimit:ꢀCH1:ꢀVOut. ꢀCH2:SoftStart.ꢀ
CH4ꢀIOutꢀ(2A/div).
12VinꢀOutputꢀRipple:ꢀCH1:VOut.ꢀCH2:
SwitchꢀNodeꢀꢀtakenꢀatꢀ3AꢀOut.
ꢀOCPꢀRepeatꢀrateꢀisꢀ107ms
12VinꢀOutputꢀRipple:ꢀCH1:ꢀVOut.
ꢀCH2:ꢀSwitchꢀNodeꢀꢀtakenꢀatꢀ0AꢀOut.
22VinꢀOutputꢀRipple:ꢀCH1:ꢀVOut.
ꢀCH2:ꢀSwitchꢀNodeꢀꢀtakenꢀatꢀ0Aꢀout.
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
ꢀ7
TYPICAL PERFORMANCE CHARACTERISTICS
Operationꢀfromꢀexernalꢀbias:ꢀ
22VinꢀTransientꢀResponseꢀ
CH2:ꢀSwitchnodeꢀ@ꢀ2.34ViN.
CH1:ꢀVOut. ꢀCH4:ꢀIOutꢀ(1A/div).
Operationꢀfromꢀexernalꢀbias:ꢀ
CH2:ꢀSwitchnodeꢀ@ꢀ3ViN, IOutꢀ=ꢀ3A.
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
18
PACKAGE: 26 PIN DFN
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
19
ORDERING INFORMATION
Part Number
Junction Temperature
Package
SP7661ER/TR..................................-40°Cꢀtoꢀ+125°C............ꢀ.......................................26ꢀPinꢀꢀ7ꢀXꢀ4ꢀDFNꢀ
(Optionꢀ2)
SP7661ER-L/TR...............................-40°Cꢀtoꢀ+125°C.........................(LeadꢀFree)ꢀ26ꢀPinꢀꢀ7ꢀXꢀ4ꢀDFNꢀ
(Optionꢀ2)
/TRꢀ=ꢀTapeꢀandꢀReel
Packꢀquantityꢀisꢀ3,000ꢀ26ꢀpinꢀDFN.
Sipex Corporation
Headquarters and
Sales Office
233ꢀSouthꢀHillviewꢀDrive
Milpitas,ꢀCAꢀ95035
TEL:ꢀ(408)ꢀ934-7500
FAX:ꢀ(408)ꢀ935-7600
SipexꢀCorporationꢀreservesꢀtheꢀrightꢀtoꢀmakeꢀchangesꢀtoꢀanyꢀproductsꢀdescribedꢀherein.ꢀSipexꢀdoesꢀnotꢀassumeꢀanyꢀliabilityꢀarisingꢀoutꢀofꢀtheꢀ
applicationꢀorꢀuseꢀofꢀanyꢀproductꢀorꢀcircuitꢀdescribedꢀherein;ꢀneitherꢀdoesꢀitꢀconveyꢀanyꢀlicenseꢀunderꢀitsꢀpatentꢀrightsꢀnorꢀtheꢀrightsꢀofꢀothers.
Mar ꢀ-07 Rev N
SP766ꢀ Wide Input Voltage Range 3A, 600kHz Buck Regulator
© 2007 Sipex Corporation
20
相关型号：
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