SC635EVB [SEMTECH]
Charge Pump Flash LED Driver; 电荷泵闪光灯LED驱动器
| 型号： | SC635EVB |
| 厂家： | 
SEMTECH CORPORATION |
| 描述： | Charge Pump Flash LED Driver |
| 文件： | 总12页 (文件大小：363K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SC635
Charge Pump
Flash LED Driver
ꢀ
POWER MANAGEMENT
Description
Features
TheꢁSC635ꢁisꢁaꢁhigh-currentꢁchargeꢁpumpꢁdesignedꢁspe-
cificallyꢀforꢀuseꢀwithꢀwhiteꢀLEDsꢀusedꢀinꢀcameraꢀflashꢀap-
plications.ꢁOnlyꢁtwoꢁsmallꢁbucketꢁcapacitorsꢁareꢁrequiredꢁ
toꢁdevelopꢁtheꢁoutputꢁdrive,ꢁprovidingꢁaꢁlowꢁEMIꢁsolutionꢁ
comparedꢁtoꢁinductiveꢁboostꢁregulators.
uꢁ Twoꢁselectableꢁmodesꢁ-ꢁFlashꢁandꢁSpotlight
uꢁ 200mAꢁmaxꢁoutputꢁ-ꢁFlashꢁMode
uꢁ Spotlightꢁmodeꢁsetꢁtoꢁ40%ꢁofꢁFlashꢁCurrent
uꢁ 3.0Vꢁtoꢁ5.25VꢁInputꢁRange
uꢀ Externalꢀpinsꢀforꢀcontrolꢀofꢀflashꢀandꢀspotlightꢀmodesꢀ
forꢁsynchronizationꢁtoꢁaꢁcameraꢁmoduleꢁorꢁgraphicsꢁ
controller
TheꢁSC635ꢁhasꢁtwoꢁmodesꢁofꢁoperation:ꢁFlashꢁmodeꢁandꢁ
Spotlightꢁmode.ꢁInꢁFlashꢁmode,ꢁtheꢁSC635ꢁisꢁcapableꢁofꢁ
deliveringꢁ 200mAꢁ toꢁ aꢁ high-intensityꢁ LEDꢁ duringꢁ imageꢁ
capture.ꢁꢁInꢁSpotlightꢁmodeꢁtheꢁSC635ꢁoutputsꢁ40%ꢁofꢁtheꢁ
Flashꢁmodeꢁcurrentꢁforꢁgeneralꢁpurposeꢁlightingꢁorꢁstatusꢁ
indication.
uꢁ Shortꢁcircuit,ꢁover-voltage,ꢁandꢁover-temperature
ꢁ
protection
uꢁ Soft-startꢁfunctionality
uꢁ MicroꢁLeadꢁPackageꢁMLPD-ꢀ0,ꢁ3mmꢁxꢁ3mm
AnꢁexternalꢁresistorꢁisꢁconnectedꢁinꢁseriesꢁwithꢁtheꢁLEDꢁtoꢁ
setꢁtheꢁcurrent.ꢁInꢁFlashꢁmode,ꢁthisꢁresistorꢁcanꢁdissipateꢁ
upꢁtoꢁ50mW,ꢁreducingꢁtheꢁpowerꢁdissipationꢁrequirementꢁ
ofꢀtheꢀSC635.ꢀTheꢀflashꢀinputꢀ(FLASH)ꢀoverridesꢀtheꢀcon-
trolꢀinputꢀ(CTRL)ꢀtoꢀmakeꢀsureꢀtheꢀflashꢀfunctionꢀisꢀacti-
vatedꢁwhenꢁcalledꢁfor.
Applications
uꢁ MobileꢁCameraꢁPhones
uꢁ DigitalꢁCameras
uꢁ PDAsꢁwithꢁBuilt-inꢁCameras
TheꢀthermallyꢀefficientꢀMLPD-10ꢀpackageꢀandꢀceramicꢀby-
passꢁandꢁbucketꢁcapacitorsꢁmakeꢁtheꢁSC635ꢁaꢁhighꢁout-
putꢁcurrentꢁdriverꢁthatꢁrequiresꢁminimalꢁPCBꢁarea.ꢁ
TypicalꢁApplicationꢁCircuit
TypicalꢁApplicationꢁCircuit
SC635
1
9
VIN
C1+
C1-
C2+
C2-
VOUT
white LED
10µF
1µF
3
VBAT
8
4
GND
1µF
1µF
6
7
5
ISET
CTRL
10
2
RSET
FLASH
FLASH
CTRL
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Decemberꢁ2,ꢁ2005
ꢀ
SC635
POWER MANAGEMENT
AbsoluteꢁMaximumꢁRatings
Exceedingꢀtheꢀspecificationsꢀbelowꢀmayꢀresultꢀinꢀpermanentꢀdamageꢀtoꢀtheꢀdeviceꢀorꢀdeviceꢀmalfunction.ꢀOperationꢀoutsideꢀofꢀtheꢀparametersꢀspecifiedꢀinꢀtheꢀ
ElectricalꢁCharacteristicsꢁsectionꢁisꢁnotꢁimplied.
Parameter
Symbol
VVIN
Maximum
-0.3 to +6.5
Units
Input Supply Voltage
Output Voltage
V
V
V
V
VVOUT
-0.3 to +6.5
Pin Voltage - FLASH, CTRL, ISET, C1-, C2-
Pin Voltage - C1+, C2+
-0.3 to VVIN + 0.3
-0.3 to VVOUT + 0.3
Thermal Resistance, Junction to Ambient
(JESD51 Standard Method)(1)
49
°C/W
qJA
VOUT Short Circuit Duration
Operating Ambient Temperature Range
Junction Temperature Range
Storage Temperature Range
Peak IR Flow Temperature
ESD Protection Level(2)
SC
TA
Indefinite
-40 to +85
-40 to +150
-60 to +150
260
s
°C
°C
°C
°C
kV
TJ
TSTG
TLEAD
VESD
2
(1)ꢀꢀCalculatedꢀfromꢀpackageꢀinꢀstillꢀair,ꢀmountedꢀtoꢀ3”ꢀxꢀ4.5”,ꢀ4ꢀlayerꢀFR4ꢀPCBꢀwithꢀthermalꢀviasꢀunderꢀtheꢀexposedꢀpadꢀasꢀperꢀJESD51ꢀstandards.
(2)ꢀꢀTestedꢀaccordingꢀtoꢀJEDECꢀstandardꢀJESD22-A114-B.
ElectricalꢁCharacteristics
Unlessꢀotherwiseꢀspecified:ꢀTAꢀ=ꢀ25°CꢀforꢀTYP,ꢀ-40°Cꢀtoꢀ+60°CꢀforꢀMINꢀandꢀMAX;
CBUCKETꢀ=ꢀCOUTꢀ=ꢀ1.0μFꢀ(ESRꢀ<ꢀ0.1Ω);ꢀCINꢀ=ꢀ10.0μF;ꢀVVINꢀ=ꢀ3.0Vꢀtoꢀ5.25V;ꢀVVOUTꢀ=ꢀ2.8Vꢀtoꢀ4.25V;ꢀRSETꢀ=ꢀ0.5Ωꢀ(0.1%).
Parameter
Symbol
Conditions
Min
Typ
Max Units
FLASH high, RISET = 1.25W
3.3V < VVIN < 4.2V
184
200
216
mA
92
2.8V < VVOUT = 4.25V
Output Current
IOUT
FLASH low, CTRL high, RISET = 1.25W
3.0V < VVIN < 4.5V
68
230
85
80
2.8V < VVOUT < 4.5V
FLASH high, RISET = 1.25W
3.3V < VVIN < 4.2V
250
100
270
mV
115
2.8V < VVOUT < 4.25V
ISET Reference Voltage
VISET
FLASH low, CTRL high, RISET = 1.25W
3.0V < VVIN < 4.5V
2.8V < VVOUT < 4.5V
FLASH high
3.4
2.0
0.1
5.0
4.5
2.0
mA
mA
µA
Quiescent Current
IQ
FLASH low, CTRL high
FLASH low, CTRL low
2005ꢁSemtechꢁCorp.
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2
SC635
POWER MANAGEMENT
ElectricalꢀCharacteristicsꢀ(Cont.)
Parameter
Symbol
Conditions
Min
Typ
indefinite
250
Max Units
t = 0 when FLASH goes high to IOUT = 90%
Flash Mode Start-up Time(1)
tF-SU
1
ms
s
of final value
3.3V < VVIN < 4.2V
IOUT = 200mA, VVOUT > 2.8V
Flash Mode Pulse Duration
tFLASH
tS-SU
t = 0 when CTRL goes high to IOUT = 90%
Spotlight Mode Start-up Time(1)
1
ms
of final value
Oscillator Frequency
fOSC
Device enabled
kHz
%
Oscillator Frequency Accuracy
DfOSC
-15
15
465
2.1
Short-circuit Output Current
Limit
ISC
VOUT shorted to GND
3.3V < VVIN < 4.2V
mA
A
Input Current Limit
ILIMIT
1.0
150
10
Over-temperature Protection(1)
TOT
°C
Hysteresis
FLASH, CTRL
Logic Input High Threshold
Logic Input Low Threshold
VIH
VIL
1.5
V
V
FLASH, CTRL
0.4
35
FLASH
1
2
20
40
Logic Input High Current
Logic Input High Current
ISET Ripple Voltage(1)
Notes:
IIH
µA
µA
CTRL
70
IIL
FLASH, CTRL
0.1
25
2.0
Spotlight mode - IOUT = 80mA
FLASH mode - IOUT = 200mA
VISET(P-P)
mV
100
(1)ꢀGuaranteedꢀbyꢀdesignꢀ-ꢀnotꢀtestedꢀinꢀproduction.
2005ꢁSemtechꢁCorp.
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3
SC635
POWER MANAGEMENT
PinꢀConfiguration
OrderingꢁInformation
DEVICE
PACKAGE(1)
SC635MLTRT(1)(2)
(2)
1(
)
MLPD-10 3x3
10
9
VIN
C2-
1
2
3
4
5
C2+
SC635EVB
Evaluation Board
TOPꢀVIEW
VOUT
C1+
Notes:
8
GND
C1-
(1) Available in tape and reel only. A reel contains 3,000 devices.
(2) Available in lead-free package only. Device is WEEE and
RoHS compliant.
7
CTRL
ISET
T
6
FLASH
MLP10:ꢀꢀ3X3ꢀ10ꢀLEAD
PinꢁDescriptions
Pin#
Pin Name Pin Function
1
2
3
4
VIN
C2-
Input voltage.
Negative terminal of bucket capacitor 2.
GND
C1-
Ground - connect to ground plane using multiple vias.
Negative terminal of bucket capacitor 1.
Flash mode enable pin - puts the device in active Flash mode when high and also overrides
CTRL.
5
FLASH
6
7
ISET
CTRL
C1+
Current-setting reference pin - connect to the LED cathode and the current setting resistor.
Control input bit - used to enable and set the output current in Spotlight mode when high.
Positive terminal of bucket capacitor 1.
8
9
VOUT
C2+
Output pin.
10
Positive terminal of bucket capacitor 2.
Thermal
Pad
Pad for heat sinking purposes - not connected internally. Connect to ground plane using
multiple vias.
T
2005ꢁSemtechꢁCorp.
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4
SC635
POWER MANAGEMENT
ApplicationsꢁInformation
GeneralꢀOperation
theꢁoutputꢁcurrentꢁbeingꢁsetꢁtooꢁlow.
Theꢀ SC635ꢀ isꢀ aꢀ powerfulꢀ 2Xꢀ chargeꢀ pumpꢀ designedꢀ toꢀ
driveꢁaꢁhigh-intensityꢁwhiteꢁLEDꢁwithꢁaꢁconstantꢁcurrentꢁ ProtectionꢀCircuitry
(Spotlightꢀmode)ꢀorꢀwithꢀaꢀpulsedꢀcurrentꢀofꢀhigherꢀinten- TheꢁSC635ꢁalsoꢁprovidesꢁprotectionꢁcircuitryꢁthatꢁpreventsꢁ
sityꢀ(Flashꢀmode)ꢀusedꢀforꢀcameraꢀflash.ꢀꢀ
theꢀdeviceꢀfromꢀoperatingꢀinꢀanꢀunspecifiedꢀstate.ꢀꢀTheseꢀ
functionsꢀ includeꢀ Inputꢀ Over-Voltageꢀ Protectionꢀ (IOVP),ꢀ
Inꢁ Flashꢁ modeꢁ theꢁ SC635ꢁ outputꢁ canꢁ driveꢁ 200mAꢁ atꢁ Outputꢀ Over-Voltageꢀ Protectionꢀ (OVP),ꢀ Over-Temperatureꢀ
4.25Vꢁ intoꢁ anꢁ LEDꢁ forꢁ anꢁ unlimitedꢁ durationꢁ underꢁ allꢁ (OT)ꢀProtection,ꢀOver-CurrentꢀProtectionꢀ(OCP),ꢀandꢀShort-
temperatureꢀandꢀinputꢀconditions.ꢀꢀTheꢀFLASHꢀpinꢀisꢀusedꢀ CircuitꢀCurrentꢀProtectionꢀ(SCCP).ꢀ
toꢀtriggerꢀthisꢀmodeꢀ(activeꢀhigh).ꢀInꢀSpotlightꢀmodeꢀtheꢀ
SC635ꢁregulatesꢁtheꢁoutputꢁcurrentꢁtoꢁ40%ꢁofꢁtheꢁFlashꢁ Input Over-Voltage Protection
modeꢁcurrentꢁsettingꢁwhenꢁtheꢁCTRLꢁpinꢁisꢁpulledꢁhighꢁ Inputꢁover-voltageꢁprotectionꢁisꢁincludedꢁtoꢁpreventꢁopera-
andꢀtheꢀFLASHꢀpinꢀisꢀlow.ꢀꢀNoteꢀthatꢀFlashꢀmodeꢀhasꢀprior- tionꢁatꢁhighꢁinputꢁvoltagesꢁthatꢁcouldꢁdamageꢁtheꢁdevice.ꢁ
ityꢀoverꢀSpotlightꢀmode,ꢀi.e.,ꢀtheꢀFLASHꢀpinꢀtriggersꢀFlashꢀ TheꢁIOVPꢁcircuitꢁsensesꢁtheꢁinputꢁvoltageꢁandꢁdeterminesꢁ
modeꢁregardlessꢁofꢁtheꢁstateꢁofꢁtheꢁCTRLꢁpin.
whenꢀtheꢀsupplyꢀexceedsꢀ6V.ꢀHysteresisꢀisꢀincludedꢀinꢀthisꢀ
circuitꢁtoꢁavoidꢁchatteringꢁbetweenꢁstates.ꢁꢁWhenꢁtheꢁvolt-
OutputꢁcurrentꢁisꢁregulatedꢁbyꢁattachingꢁtheꢁISETꢁpinꢁtoꢁ ageꢁrisesꢁaboveꢁthisꢁthreshold,ꢁtheꢁdeviceꢁisꢁdisabledꢁun-
theꢀcathode(s)ꢀofꢀtheꢀLEDꢀpackageꢀandꢀaꢀlowꢀresistanceꢀ tilꢀtheꢀinputꢀvoltageꢀdropsꢀtoꢀaꢀlevelꢀwithinꢀtheꢀspecifiedꢀ
senseꢀresistorꢀ(typicallyꢀ1.25Ω).ꢀꢀTheꢀISETꢀpinꢀmonitorsꢀ range.
theꢁvoltageꢁatꢁtheꢁcathodeꢁandꢁsignalsꢁtheꢁchargeꢁpumpꢁ
toꢁincreaseꢁorꢁdecreaseꢁtheꢁoutputꢁcurrentꢁuntilꢁtheꢁISETꢁ Output Over-Voltage Protection
voltageꢁ reachesꢁ theꢁ programmedꢁ setting.ꢁ ꢁ Theꢁ resistorꢁ Outputꢁover-voltageꢁprotectionꢁisꢁincludedꢁtoꢁpreventꢁtheꢁ
valueꢁisꢁchosenꢁtoꢁsetꢁtheꢁcurrentꢁthroughꢁtheꢁLEDꢁbasedꢁ SC635ꢁfromꢁgeneratingꢁanꢁoutputꢁvoltageꢁthatꢁcouldꢁdam-
onꢁthisꢁreferenceꢁvoltage.ꢁꢁꢁ
ageꢁotherꢁdevicesꢁconnectedꢁtoꢁitꢁsuchꢁasꢁloadꢁLEDsꢁandꢁ
bypassꢁcapacitors.ꢁWhenꢁtheꢁoutputꢁvoltageꢁexceedsꢁ5.5V,ꢁ
theꢁOVPꢁcircuitꢁdisablesꢁtheꢁchargeꢁpumpꢁuntilꢁtheꢁvoltageꢁ
FlashꢀMode
FlashꢀmodeꢀisꢀenabledꢀwheneverꢀtheꢀFLASHꢀpinꢀisꢀpulledꢀ decreasesꢁtoꢁaꢁlevelꢁwithinꢁtheꢁacceptableꢁrange.ꢁꢁThisꢁ
highꢀandꢀremainsꢀactiveꢀuntilꢀtheꢀFLASHꢀpinꢀisꢀreleased.ꢀ circuitꢁallowsꢁtheꢁdeviceꢁtoꢁdriveꢁLEDsꢁwithꢁhighꢁforwardꢁ
ThisꢁmodeꢁhasꢁhigherꢁpriorityꢁthanꢁSpotlightꢁmode,ꢁsoꢁtheꢁ voltagesꢁatꢁaꢁreducedꢁlevelꢁwithoutꢁexceedingꢁtheꢁoutputꢁ
stateꢀofꢀtheꢀCTRLꢀpinꢀisꢀoverriddenꢀwheneverꢀtheꢀFLASHꢀ voltageꢀlimitsꢀspecifiedꢀforꢀtheꢀdevice.ꢀNote,ꢀhowever,ꢀthatꢀ
pinꢁisꢁactivated.ꢁꢁWhileꢁinꢁFlashꢁmodeꢁtheꢁreferenceꢁvolt- thisꢁeffectꢁisꢁaꢁconsequenceꢁofꢁtheꢁOVPꢁcircuitꢁandꢁisꢁnotꢁ
ageꢁonꢁtheꢁISETꢁpinꢁisꢁsetꢁtoꢁ250mV.ꢁꢁꢁ
itsꢁintendedꢁpurpose.
Outputꢁcurrentsꢁotherꢁthanꢁtheꢁratedꢁmaximumꢁofꢁ200mAꢁ Over-Temperature Protection
canꢁbeꢁsetꢁbyꢁchangingꢁtheꢁRISETꢁvalue.ꢁꢁInꢁFlashꢁmode,ꢁ Theꢁ over-temperatureꢁ circuitꢁ helpsꢁ preventꢁ theꢁ deviceꢁ
IOUTꢀ=ꢀ250mV/RISET.ꢁꢁ
fromꢁ overheatingꢁ andꢁ experiencingꢁ aꢁ catastrophicꢁ fail-
ure.ꢀꢀWhenꢀtheꢀjunctionꢀtemperatureꢀexceedsꢀ150°Cꢀtheꢀ
deviceꢁisꢁdisabled.ꢁꢁItꢁremainsꢁdisabledꢁuntilꢁtheꢁjunctionꢁ
SpotlightꢀMode
SpotlightꢁmodeꢁisꢁenabledꢁbyꢁsettingꢁtheꢁCTRLꢁpinꢁhighꢁ temperatureꢁdropsꢁbelowꢁthisꢁthreshold.ꢁꢁAsꢁwithꢁtheꢁUVLOꢁ
andꢀkeepingꢀtheꢀFLASHꢀpinꢀlow.ꢀꢀWhenꢀinꢀSpotlightꢀmode,ꢀ andꢁOVPꢁcircuits,ꢁhysteresisꢁisꢁincludedꢁtoꢁpreventꢁtogglingꢁ
theꢀSC635ꢀcanꢀmaintainꢀaꢀconstantꢀcurrentꢀindefinitelyꢀtoꢀ betweenꢁmodes.
driveꢁanꢁLEDꢁorꢁbankꢁofꢁLEDs.ꢁTheꢁISETꢁreferenceꢁvoltageꢁ
isꢁsetꢁtoꢁꢀ00mVꢁsoꢁthatꢁtheꢁoutputꢁcurrentꢁisꢁmaintainedꢁ Over-Current Protection
atꢀ80mAꢀwhenꢀaꢀ1.25Ωꢀresistorꢀisꢀused.ꢀꢀSpotlightꢀcurrentꢀ Whenꢀ theꢀ SC635ꢀ isꢀ inꢀ 2Xꢀ mode,ꢀ theꢀ inputꢀ currentꢀ willꢀ
isꢀalwaysꢀ40%ꢀofꢀflashꢀcurrentꢀforꢀanyꢀgivenꢀvalueꢀofꢀRISET.ꢁ beꢁapproximatelyꢁdoubleꢁtheꢁrequiredꢁoutput.ꢁꢁWhenꢁtheꢁ
Inꢀspotlightꢀmode,ꢀIOUTꢀ=ꢀ100mV/RISET.ꢁꢁTheꢁresistorꢁval- steady-stateꢁloadꢁrequiresꢁtheꢁmaximumꢁcurrentꢁavailableꢁ
ueꢀshouldꢀnotꢀexceedꢀ2Ω,ꢀhowever,ꢀtoꢀensureꢀtheꢀSC635ꢀ inꢀ2Xꢀmode,ꢀtheꢀOCPꢀcircuitꢀpreventsꢀtheꢀdeviceꢀfromꢀover-
doesꢁnotꢁbecomeꢁunstableꢁwhileꢁinꢁSpotlightꢁmodeꢁdueꢁtoꢁ heatingꢁdueꢁtoꢁexcessiveꢁpowerꢁdissipation.
2005ꢁSemtechꢁCorp.
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5
SC635
POWER MANAGEMENT
ApplicationsꢀInformationꢀ(Cont.)
Short-Circuit Current Protection
ofꢀDCꢀdropꢀacrossꢀtheꢀreturnꢀcopperꢀtraceꢀinꢀflashꢀmode.ꢀ
Short-circuitꢁcurrentꢁprotectionꢁisꢁprovidedꢁtoꢁlimitꢁtheꢁcur- Forꢁthisꢁreason,ꢁitꢁisꢁcrucialꢁtoꢁhaveꢁaꢁlowꢁresistanceꢁreturnꢁ
rentꢁthatꢁcanꢁbeꢁsourcedꢁwhenꢁtheꢁoutputꢁisꢁshortedꢁtoꢁ path.ꢁPlaceꢁandꢁgroundꢁtheꢁresistorꢁasꢁcloseꢁasꢁpossibleꢁ
ground.ꢁWhenꢁaꢁshortꢁcircuitꢁforcesꢁVOUTꢁtoꢁdropꢁbelowꢁ toꢁtheꢁgroundꢁpinꢁofꢁtheꢁSC635.ꢁTheꢁtraceꢁfromꢁtheꢁISETꢁ
2V,ꢁtheꢁSCCPꢁdetectsꢁtheꢁconditionꢁandꢁlimitsꢁtheꢁoutputꢁ pinꢁhasꢁvirtuallyꢁnoꢁcurrent.ꢁTheꢁISETꢁtraceꢁshouldꢁmakeꢁ
current.
contactꢁatꢁtheꢁpadꢁofꢁtheꢁpowerꢁsenseꢁresistorꢁtoꢁminimizeꢁ
theꢁeffectꢁofꢁvoltageꢁdropꢁbetweenꢁtheꢁLEDꢁcathodeꢁandꢁ
theꢁresistor.
ResistorꢀSelection
TheꢁISETꢁresistorꢁselectionꢁisꢁcriticalꢁinꢁgeneratingꢁtheꢁcor-
rectꢁcurrent.ꢁꢁTheꢁvalueꢁcanꢁbeꢁchosenꢁtoꢁsetꢁtheꢁSpotlightꢁ CapacitorꢀSelection
modeꢁcurrentꢁorꢁtheꢁFlashꢁmodeꢁcurrent,ꢁbutꢁitꢁmustꢁbeꢁ TheꢁSC635ꢁisꢁdesignedꢁtoꢁuseꢁlow-ESRꢁceramicꢁcapaci-
notedꢁthatꢁtheꢁtwoꢁcurrentꢁsettingsꢁareꢁdependentꢁonꢁtheꢁ torsꢁforꢁtheꢁinputꢁandꢁoutputꢁbypassꢁcapacitorsꢁasꢁwellꢁasꢁ
sameꢁresistance.ꢁꢁItꢁisꢁrecommendedꢁthatꢁtheꢁresistorꢁbeꢁ theꢁchargeꢁpumpꢁbucketꢁcapacitors.ꢁꢁIdealꢁperformanceꢁ
selectedꢁtoꢁmatchꢁtheꢁdesiredꢁLEDꢁcurrentꢁforꢁFlashꢁmode.ꢁ isꢁachievedꢁwhenꢁCꢀꢁisꢁexactlyꢁequalꢁtoꢁC2.ꢁꢁItꢁisꢁrecom-
ThisꢁallowsꢁtheꢁdesignerꢁtoꢁsetꢁtheꢁSC635’sꢁmaximumꢁcur- mendedꢀthatꢀX5RꢀorꢀX7Rꢀceramicꢀcapacitorsꢀbeꢀusedꢀforꢀ
rentꢁandꢁselectꢁtheꢁresistorꢁpackageꢁsizeꢁnecessaryꢁforꢁ bestꢁperformance.
theꢁpowerꢁdissipationꢁrequiredꢁinꢁFlashꢁmode.ꢁꢁTheꢁtypicalꢁ
applicationꢀshownꢀonꢀpageꢀ1ꢀusesꢀaꢀ1.25Ωꢀresistorꢀtoꢀsetꢀ ThermalꢀResistance
aꢀflashꢀmodeꢀcurrentꢀofꢀ200mAꢀandꢀspotlightꢀmodeꢀcur- TheꢀSC635ꢀpackageꢀisꢀthermallyꢀefficientꢀwhenꢀtheꢀcircuitꢀ
rentꢀofꢀ80mA.ꢀꢀAꢀhighꢀprecisionꢀresistorꢀshouldꢀbeꢀusedꢀtoꢀ boardꢁlayoutꢁconnectsꢁtheꢁthermalꢁpadꢁthoughꢁmultipleꢁ
ensureꢀtheꢀspecifiedꢀaccuracyꢀforꢀLEDꢀcurrent.ꢀꢀ
viasꢁtoꢁtheꢁgroundꢁplane.ꢁꢁTheꢁthermalꢁresistanceꢁisꢁratedꢁ
atꢀ49°C/W,ꢀandꢀthisꢀratingꢀisꢀdependentꢀonꢀtheꢀconnec-
Toꢁ avoidꢁ malfunctionꢁ ofꢁ theꢁ chargeꢁ pump,ꢁ itꢁ isꢁ recom- tionꢁbetweenꢁtheꢁthermalꢁpadꢁandꢁtheꢁgroundꢁplane.ꢁꢁAꢁ
mendedꢁthatꢁtheꢁresistanceꢁseenꢁatꢁtheꢁISETꢁpinꢁremainꢁ layoutꢁthatꢁisꢁdoneꢁcorrectlyꢁshouldꢁkeepꢁtheꢁjunctionꢁtem-
constantꢀ whileꢀ theꢀ deviceꢀ isꢀ activeꢀ (Flashꢀ orꢀ Spotlightꢀ peratureꢁbelowꢁtheꢁOTꢁ limitꢁwhileꢁ operatingꢁtheꢁSC635ꢁ
mode).ꢀꢀChangingꢀtheꢀresistanceꢀvalueꢀorꢀtheꢀloadꢀcur- withinꢀtheꢀspecifiedꢀelectricalꢀconditionsꢀforꢀIOUTꢀandꢀVISET.ꢁ
rentꢁwhileꢁtheꢁdeviceꢁisꢁactiveꢁcouldꢁcauseꢁinstabilityꢁthatꢁ Aꢁpoorꢁlayoutꢁmayꢁallowꢁtheꢁjunctionꢁtemperatureꢁtoꢁreachꢁ
wouldꢁresultꢁinꢁnon-compliantꢁbehavior.ꢁ
theꢁOTꢁlimitꢁwhileꢁinꢁFlashꢁorꢁSpotlightꢁmode.ꢁItꢁisꢁcriticalꢁ
toꢁmaintainꢁadequateꢁgroundꢁplaneꢁaroundꢁtheꢁdeviceꢁtoꢁ
TheꢁloadꢁcurrentꢁreturnꢁpathꢁisꢁfromꢁtheꢁISETꢁsenseꢁpointꢁ maximizeꢁheatꢁtransferꢁandꢁavoidꢁover-temperatureꢁshut-
throughꢁtheꢁresistorꢁandꢁbackꢁtoꢁtheꢁgroundꢁpins.ꢁꢁResis- down.
tanceꢁinꢁthisꢁpathꢁaddsꢁtoꢁtheꢁtotalꢁresistanceꢁandꢁhasꢁtheꢁ
effectꢁofꢁreducingꢁtheꢁLEDꢁcurrentꢁbyꢁaboutꢁ4%ꢁperꢁꢀ0mVꢁ
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6
SC635
POWER MANAGEMENT
TypicalꢁCharacteristics
200mAꢀFlashꢀDuration,ꢀRISETꢀ=ꢀ1.25W,
FlashꢀCurrentꢀatꢀ500ms,ꢀRISETꢀ=ꢀ1.25W,ꢀVOUTꢀ=ꢀ3.25V
VOUTꢀ=ꢀ3.30V(start)ꢀtoꢀ3.25V(LEDꢀheatedꢀ500ms)
205.0
205.0
203.0
203.0
201.0
199.0
197.0
195.0
201.0
VIN = 4.2V
VIN = 3.7V
199.0
VIN = 3.3V
197.0
195.0
0
100
200
300
400
500
3.3
3.45
3.6
3.75
3.9
4.05
4.2
VIN [V]
Pulse Duration [ms]
FlashꢀCurrentꢀatꢀ100ms,ꢀRISETꢀ=ꢀ1.25W,ꢀVOUTꢀ=ꢀ3.28V
FlashꢀCurrentꢀatꢀ10ms,ꢀRISETꢀ=ꢀ1.25W,ꢀVOUTꢀ=ꢀ3.30V
205.0
205.0
203.0
201.0
199.0
197.0
195.0
203.0
201.0
199.0
197.0
195.0
3.3
3.45
3.6
3.75
3.9
4.05
4.2
3.3
3.45
3.6
3.75
3.9
4.05
4.2
VIN [V]
VIN [V]
80mAꢀSpotlightꢀCurrent,ꢀRISETꢀ=ꢀ1.25W,ꢀVOUTꢀ=ꢀ2.96V
85.0
83.0
81.0
79.0
77.0
75.0
3
3.45
3.9
4.35
4.8
5.25
VIN [V]
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7
SC635
POWER MANAGEMENT
TypicalꢀCharacteristicsꢀ(Cont.)
FlashꢀModeꢀRipple,ꢀRISETꢀ=ꢀ1.25W
SpotlightꢀModeꢀRipple,ꢀRISETꢀ=ꢀ1.25W
Ch1ꢀ50mV/div
Ch1ꢀ50mV/div
Ch2ꢀ100mV/div
Ch3ꢀ100mV/div
4us/div
Ch2ꢀ200mV/div
Ch3ꢀ200mV/div
4us/div
StartupꢀFlashꢀModeꢀ200mA
Ch1ꢀ100mV/div
Ch2ꢀ2V/div
Ch3ꢀ2V/div
Ch4ꢀ2V/div
40us/div
2005ꢁSemtechꢁCorp.
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8
SC635
POWER MANAGEMENT
SuggestedꢁLayout
TheꢁsenseꢁtraceꢁbetweenꢁPinꢁ6ꢁandꢁRꢀꢁisꢁroutedꢁaroundꢁ
theꢁgroundꢁvias,ꢁallowingꢁtheꢁshortestꢁgroundꢁreturnꢁpathꢁ
possible.ꢁꢁTheꢁsenseꢁtraceꢁisꢁconnectedꢁtoꢁRꢀꢁatꢁtheꢁposi-
tiveꢁterminalꢁpadꢁforꢁtheꢁmostꢁaccurateꢁoutputꢁpossible.ꢁ
Theꢁbottomꢁcopperꢁlayerꢁisꢁmostlyꢁaꢁgroundꢁplaneꢁwithꢁnoꢁ
obstructionsꢁbetweenꢁtheꢁgroundꢁvias.ꢁꢁTheꢁsmallerꢁrect-
angleꢀtoꢀtheꢀleftꢀconnectsꢀtheꢀinputꢀpowerꢀtoꢀVINꢀpinꢀ1ꢀandꢀ
inputꢁcapacitorꢁC4.ꢁꢁTheꢁtwoꢁtracesꢁatꢁtheꢁlowerꢁleftꢁareꢁforꢁ
logicꢀinputsꢀFLASHꢀandꢀCTRL.ꢀꢀTheꢀtraceꢀtoꢀtheꢀrightꢀisꢀtheꢀ
ISETꢀpinꢀ“sense”ꢀtrace.ꢀꢀTheꢀsenseꢀtraceꢀisꢀroutedꢀoutꢀofꢀ
theꢁpathꢁofꢁtheꢁreturningꢁgroundꢁcurrent.
LayoutꢀGuidelines
Theꢁfollowingꢁlayoutꢁisꢁsuggestedꢁforꢁaꢁtwo-layerꢁdesign.ꢁ
TheꢁcapacitorsꢁCꢀꢁandꢁC2ꢁareꢁtheꢁbucketꢁcapacitorsꢁandꢁ
eachꢁconductsꢁtheꢁfullꢁloadꢁcurrentꢁofꢁupꢁtoꢁ200mAꢁpulsedꢁ
forꢁoneꢁhalfꢁclockꢁcycle.ꢁꢁC3ꢁisꢁtheꢁoutputꢁdecouplingꢁca-
pacitorꢁplacedꢁnearꢁtheꢁSC635ꢁVOUTꢁpin.ꢁꢁC4ꢁisꢁtheꢁin-
putꢀdecouplingꢀcapacitorꢀplacedꢀnearꢀtheꢀSC635ꢀVINꢀpin.ꢀ
Multipleꢁviasꢁshouldꢁbeꢁusedꢁwheneverꢁitꢁisꢁnecessaryꢁtoꢁ
changeꢀlayersꢀonꢀnetsꢀconnectingꢀtoꢀpinsꢀVIN,ꢀVOUT,ꢀGND,ꢀ
C1-,ꢀC1+,ꢀC2-ꢀandꢀC2+.ꢀResistorꢀR1ꢀisꢀroutedꢀwithꢀaꢀveryꢀ
lowꢀresistanceꢀconnectionꢀbetweenꢀR1ꢀandꢀGNDꢀpinꢀ3.ꢀ
BottomꢀCopper
TopꢀCopper
2005ꢁSemtechꢁCorp.
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ꢂ
SC635
POWER MANAGEMENT
BlockꢁDiagram
VIN
1
LDO
8
4
Cꢀ+
250kHz
Cꢀ-
10 C2+
CTRL
7
5
LogicꢁControl
CHARGE
PUMP
2
9
C2-
FLASH
Referenceꢁ
Voltageꢁ
Generator
VOUT
3
6
GND
ISET
2005ꢁSemtechꢁCorp.
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ꢀ0
SC635
POWER MANAGEMENT
OutlineꢁDrawingꢁ-ꢁMLPD-ꢀ0
DIMENSIONS
INCHES MILLIMETERS
A
E
B
E
DIM
MIN NOM MAX MIN NOM MAX
-
-
-
-
A
.031
A1 .000
.039 0.80
.002 0.00
1.00
0.05
-
-
-
-
(.008)
(0.20)
A2
b
C
D
E
e
.007 .009 .011 0.18 0.23 0.30
.074 .079 .083 1.87 2.02 2.12
.042 .048 .052 1.06 1.21 1.31
.114 .118 .122 2.90 3.00 3.10
PIN 1
INDICATOR
.020 BSC
0.50 BSC
(LASER MARK)
L
N
.012 .016 .020 0.30 0.40 0.50
10
10
aaa
bbb
.003
.004
0.08
0.10
A
C
SEATING
PLANE
aaa C
A1
A2
C
1
2
LxN
D
N
bxN
bbb
e
C
A
B
NOTES:
1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES).
2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS.
MarkingꢁInformation
Top Mark
635
yyww
xxxx
yyww = Datecode (Example = 0552)
xxxx = Semtech Lot Number
2005ꢁSemtechꢁCorp.
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ꢀꢀ
SC635
POWER MANAGEMENT
LandꢁPatternꢁ-ꢁMLPD-ꢀ0
DIMENSIONS
K
DIM
INCHES
MILLIMETERS
(.112)
.075
.055
.087
.020
.012
.037
.150
(2.85)
1.90
1.40
2.20
0.50
0.30
0.95
3.80
C
G
H
K
P
X
Y
Z
H
G
Y
(C)
Z
X
P
NOTES:
1. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY.
CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR
COMPANY'S MANUFACTURING GUIDELINES ARE MET.
ContactꢁInformation
SemtechꢁCorporation
PowerꢁManagementꢁProductsꢁDivision
200ꢁFlynnꢁRoad,ꢁCamarillo,ꢁCAꢁꢂ30ꢀ2
Phone:ꢀ(805)ꢀ498-2111ꢀꢀꢀFAX:ꢀ(805)ꢀ498-3804
2005ꢁSemtechꢁCorp.
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ꢀ2
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