LTC3526LB_15 [Linear]
550mA 1MHz Synchronous Step-Up DC/DC Converters;
| 型号： | LTC3526LB_15 |
| 厂家： | 
Linear |
| 描述： | 550mA 1MHz Synchronous Step-Up DC/DC Converters |
| 文件： | 总16页 (文件大小：349K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3526L/LTC3526LB
550mA 1MHz Synchronous
Step-Up DC/DC Converters
in 2mm × 2mm DFN
Description
FeAtures
ꢀ Delivers 3.3V at 100mA from a Single Alkaline/
Theꢀ LTC®3526L/LTC3526LBꢀ areꢀ synchronous,ꢀ fixedꢀ
frequencyꢀstep-upꢀDC/DCꢀconvertersꢀwithꢀoutputꢀdiscon-
nect.ꢀSynchronousꢀrectificationꢀenablesꢀhighꢀefficiencyꢀinꢀ
theꢀlowꢀprofileꢀ2mmꢀ×ꢀ2mmꢀDFNꢀpackage.ꢀBatteryꢀlifeꢀinꢀ
singleꢀAA/AAAꢀpoweredꢀproductsꢀisꢀextendedꢀfurtherꢀwithꢀ
aꢀ680mVꢀstart-upꢀvoltageꢀandꢀoperationꢀdownꢀtoꢀ500mVꢀ
onceꢀstarted.
n
NiMH Cell or 3.3V at 200mA from Two Cells
IN
n
ꢀ V Start-Up Voltage: 680mV
n
n
n
n
n
n
n
n
n
n
n
n
n
ꢀ 1.5V to 5.25V V
Range
OUT
ꢀ Up to 94% Efficiency
ꢀ Output Disconnect
ꢀ 1MHz Fixed Frequency Operation
ꢀ V > V
Operation
IN
OUT
Aꢀswitchingꢀfrequencyꢀofꢀ1MHzꢀminimizesꢀsolutionꢀfoot-
printꢀbyꢀallowingꢀtheꢀuseꢀofꢀtiny,ꢀlowꢀprofileꢀinductorsꢀ
andꢀceramicꢀcapacitors.ꢀTheꢀcurrentꢀmodeꢀPWMꢀdesignꢀ
isꢀinternallyꢀcompensated,ꢀreducingꢀexternalꢀpartsꢀcount.ꢀ
TheꢀLTC3526LꢀfeaturesꢀBurstꢀModeꢀoperationꢀatꢀlightꢀloadꢀ
conditionsꢀallowingꢀitꢀtoꢀmaintainꢀhighꢀefficiencyꢀoverꢀaꢀ
wideꢀrangeꢀofꢀload.ꢀTheꢀLTC3526LBꢀfeaturesꢀfixedꢀfrequencyꢀ
operationꢀforꢀlowꢀnoiseꢀapplications.ꢀAnti-ringꢀcircuitryꢀ
reducesꢀEMIꢀbyꢀdampingꢀtheꢀinductorꢀinꢀdiscontinuousꢀ
mode.ꢀAdditionalꢀfeaturesꢀincludeꢀaꢀlowꢀshutdownꢀcurrentꢀ
ofꢀunderꢀ1µAꢀandꢀthermalꢀshutdown.
ꢀ Integrated Soft-Start
ꢀ CurrentꢀModeꢀControlꢀwithꢀInternalꢀCompensation
®
ꢀ BurstꢀMode ꢀOperationꢀwithꢀ9µAꢀI ꢀ(LTC3526L)
Q
ꢀ LowꢀNoiseꢀPWMꢀOperationꢀ(LT3526LB)
ꢀ InternalꢀSynchronousꢀRectifier
ꢀ LogicꢀControlledꢀShutdownꢀ(I ꢀ<ꢀ1µA)
Q
ꢀ Anti-RingꢀControl
ꢀ LowꢀProfileꢀ(2mmꢀ×ꢀ2mmꢀ×ꢀ0.75mm)ꢀꢀ
DFN-6ꢀPackage
ApplicAtions
TheꢀLTC3526L/LTC3526LBꢀareꢀhousedꢀinꢀaꢀ2mmꢀ×ꢀ2mmꢀ
×ꢀ0.75mmꢀDFNꢀpackage.
L,ꢀLT,ꢀLTC,ꢀLTM,ꢀLinearꢀTechnology,ꢀtheꢀLinearꢀlogoꢀandꢀBurstꢀModeꢀareꢀregisteredꢀtrademarksꢀ
andꢀThinSOTꢀisꢀaꢀtrademarkꢀofꢀLinearꢀTechnologyꢀCorporation.ꢀAllꢀotherꢀtrademarksꢀareꢀtheꢀ
propertyꢀofꢀtheirꢀrespectiveꢀowners.
n
ꢀ MedicalꢀInstruments
n
ꢀ NoiseꢀCancelingꢀHeadphones
n
ꢀ WirelessꢀMice
n
ꢀ BluetoothꢀHeadsets
typicAl ApplicAtion
Efficiency and Power Loss vs Load Current
100
1000
100
10
V
= 2.4V
IN
4.7µH
90
EFFICIENCY
80
SW
70
V
OUT
V
IN
3.3V
V
IN
V
OUT
60
50
1.6V TO 3.2V
200mA
4.7µF
LTC3526L
SHDN FB
GND
1.78M
1M
POWER LOSS
4.7µF
OFF ON
40
30
20
10
0
1
3526l TA01a
0.1
0.01
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA01b
3526lfc
ꢀ
DC
............................................................ –0.3Vꢀtoꢀ6Vꢀ
V
............................................................. –0.3Vꢀtoꢀ6V
(Notesꢀ2,ꢀ5)..............................................–40°Cꢀtoꢀ85°C
StorageꢀTemperatureꢀRangeꢀ.................. –65°Cꢀtoꢀ150°C
V ꢀVoltage................................................... –0.3Vꢀtoꢀ6V
LTC3526L/LTC3526LB
Absolute MAxiMuM rAtings
pin conFigurAtion
(Note 1)
TOP VIEW
IN
SWꢀVoltageꢀ
SW
1
2
3
6
5
4
V
OUT
GND
7
FB
Pulsedꢀ<100nsꢀ......................................... –0.3Vꢀtoꢀ7V
SHDN,ꢀFBꢀVoltageꢀ........................................ –0.3Vꢀtoꢀ6V
V
SHDN
IN
DC PACKAGE
6-LEAD (2mm s 2mm) PLASTIC DFN
ꢀ=ꢀ125°C,ꢀθ ꢀ=ꢀ102°C/Wꢀ(NOTEꢀ6)ꢀ
JA
EXPOSEDꢀPADꢀ(PINꢀ7)ꢀISꢀGND,ꢀMUSTꢀBEꢀSOLDEREDꢀTOꢀPCꢀBOARD
OUT
ꢀ
OperatingꢀTemperatureꢀRange
T
JMAX
orDer inForMAtion
LEAD FREE FINISH
LTC3526LEDC#PBF
LTC3526LBEDC#PBF
TAPE AND REEL
PART MARKING
LCSS
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3526LEDC#TRPBF
LTC3526LBEDC#TRPBF
–40°Cꢀtoꢀ85°C
–40°Cꢀtoꢀ85°C
6-Leadꢀ(2mmꢀ×ꢀ2mm)ꢀPlasticꢀDFN
6-Leadꢀ(2mmꢀ×ꢀ2mm)ꢀPlasticꢀDFN
LCST
ConsultꢀLTCꢀMarketingꢀforꢀpartsꢀspecifiedꢀwithꢀwiderꢀoperatingꢀtemperatureꢀranges.ꢀ
ConsultꢀLTCꢀMarketingꢀforꢀinformationꢀonꢀnon-standardꢀleadꢀbasedꢀfinishꢀparts.
Forꢀmoreꢀinformationꢀonꢀleadꢀfreeꢀpartꢀmarking,ꢀgoꢀto:ꢀhttp://www.linear.com/leadfree/ꢀꢀ
Forꢀmoreꢀinformationꢀonꢀtapeꢀandꢀreelꢀspecifications,ꢀgoꢀto:ꢀhttp://www.linear.com/tapeandreel/
The l denotes the specifications which apply over the specified operating
electricAl chArActeristics
temperature range of –40°C to 85°C, otherwise specifications are at TA = 25°C. VIN = 1.2V, VOUT = 3.3V unless otherwise noted.
PARAMETER
CONDITIONS
ꢀ=ꢀ1mA
MIN
TYP
MAX
0.8
5
UNITS
V
MinimumꢀStart-UpꢀInputꢀVoltage
InputꢀVoltageꢀRange
I
0.68
LOAD
l
l
l
AfterꢀStart-Up.ꢀ(MinimumꢀVoltageꢀisꢀLoadꢀDependent)
0.5
1.5
V
OutputꢀVoltageꢀAdjustꢀRange
FeedbackꢀPinꢀVoltage
5.25
1.225
50
V
1.165
1.195
1
V
FeedbackꢀPinꢀInputꢀCurrentꢀ
QuiescentꢀCurrent—Shutdown
QuiescentꢀCurrent—Active
QuiescentꢀCurrent—Burst
V
V
ꢀ=ꢀ1.30V
nA
µA
µA
µA
µA
µA
Ω
FB
ꢀ=ꢀ0V,ꢀNotꢀIncludingꢀSwitchꢀLeakage,ꢀV ꢀ=ꢀ0V
SHDN
0.01
250
9
1
OUT
MeasuredꢀonꢀV ,ꢀNonswitching
500
18
OUT
MeasuredꢀonꢀV ,ꢀFBꢀ>ꢀ1.230Vꢀ(LTC3526LꢀOnly)
OUT
N-ChannelꢀMOSFETꢀSwitchꢀLeakageꢀCurrent
P-ChannelꢀMOSFETꢀSwitchꢀLeakageꢀCurrent
N-ChannelꢀMOSFETꢀSwitchꢀOnꢀResistance
P-ChannelꢀMOSFETꢀSwitchꢀOnꢀResistance
N-ChannelꢀMOSFETꢀCurrentꢀLimit
CurrentꢀLimitꢀDelayꢀtoꢀOutput
MaximumꢀDutyꢀCycle
V
V
V
V
ꢀ=ꢀ5V
0.1
0.1
0.4
0.6
750
60
5
SW
SW
ꢀ=ꢀ5V,ꢀV ꢀ=ꢀ0V
10
OUT
ꢀ=ꢀ3.3V
OUT
OUT
ꢀ=ꢀ3.3V
Ω
l
550
87
mA
ns
%
(Noteꢀ3)
l
l
l
V
V
ꢀ=ꢀ1.15V
FB
ꢀ=ꢀ1.3V
FB
90
MinimumꢀDutyꢀCycle
0
%
SwitchingꢀFrequency
0.75
0.8
1
1.25
MHz
V
SHDNꢀPinꢀInputꢀHighꢀVoltage
SHDNꢀPinꢀInputꢀLowꢀVoltage
0.3
V
3526lfc
ꢁ
LTC3526L/LTC3526LB
electricAl chArActeristics
Note 1:ꢀStressesꢀbeyondꢀthoseꢀlistedꢀunderꢀAbsoluteꢀMaximumꢀRatingsꢀ
mayꢀcauseꢀpermanentꢀdamageꢀtoꢀtheꢀdevice.ꢀExposureꢀtoꢀanyꢀAbsoluteꢀ
MaximumꢀRatingꢀconditionꢀforꢀextendedꢀperiodsꢀmayꢀaffectꢀdeviceꢀ
reliabilityꢀandꢀlifetime.
Note 4:ꢀCurrentꢀmeasurementsꢀareꢀmadeꢀwhenꢀtheꢀoutputꢀisꢀnotꢀswitching.
Note 5:ꢀThisꢀICꢀincludesꢀovertemperatureꢀprotectionꢀthatꢀisꢀintendedꢀ
toꢀprotectꢀtheꢀdeviceꢀduringꢀmomentaryꢀoverloadꢀconditions.ꢀJunctionꢀ
temperatureꢀwillꢀexceedꢀ125°Cꢀwhenꢀovertemperatureꢀprotectionꢀisꢀactive.ꢀ
Continuousꢀoperationꢀaboveꢀtheꢀspecifiedꢀmaximumꢀoperatingꢀjunctionꢀ
temperatureꢀmayꢀresultꢀinꢀdeviceꢀdegradationꢀorꢀfailure.
Note 6:ꢀFailureꢀtoꢀsolderꢀtheꢀexposedꢀbacksideꢀofꢀtheꢀpackageꢀtoꢀtheꢀPCꢀ
boardꢀgroundꢀplaneꢀwillꢀresultꢀinꢀaꢀthermalꢀresistanceꢀmuchꢀhigherꢀthanꢀ
102°C/W.
Note 2:ꢀTheꢀLTC3526LE/LTC3526LBEꢀareꢀguaranteedꢀtoꢀmeetꢀperformanceꢀ
specificationsꢀfromꢀ0°Cꢀtoꢀ85°C.ꢀSpecificationsꢀoverꢀ–40°Cꢀtoꢀ85°Cꢀ
operatingꢀtemperatureꢀrangeꢀareꢀassuredꢀbyꢀdesign,ꢀcharacterizationꢀandꢀ
correlationꢀwithꢀstatisticalꢀprocessꢀcontrols.
Note 3:ꢀSpecificationꢀisꢀguaranteedꢀbyꢀdesignꢀandꢀnotꢀ100%ꢀtestedꢀinꢀ
production.
typicAl perForMAnce chArActeristics
Efficiency vs Load Current and VIN
for VOUT = 1.8V (LTC3526L)
Efficiency vs Load Current and VIN
for VOUT = 3.3V (LTC3526L)
No-Load Input Current vs VIN
(LTC3526L)
100
90
1000
100
10
100
90
1000
100
10
100
90
80
70
60
50
40
30
20
10
V
= 5V
OUT
80
80
V
V
V
V
= 1.2V
= 1.8V
= 2.4V
= 3.0V
IN
IN
IN
IN
V
V
V
= 1.0V
= 1.2V
= 1.5V
70
70
IN
IN
IN
V
= 3.3V
OUT
V
60
50
60
50
= 2.5V
OUT
V
= 1.8V
OUT
40
30
20
10
0
1
40
30
20
10
0
1
PLOSS AT V = 1.2V
IN
0.1
0.01
0.1
0.01
PLOSS AT V = 1.0V
PLOSS AT V = 1.8V
IN
IN
PLOSS AT V = 1.2V
IN
PLOSS AT V = 2.4V
IN
PLOSS AT V = 1.5V
IN
PLOSS AT V = 3.0V
IN
2.5 3.0
(V)
0.5 1.0 1.5 2.0
3.5 4.0 4.5
0.01
0.1
1
10
100
1000
0.01
0.1
1
10
100
1000
V
LOAD CURRENT (mA)
LOAD CURRENT (mA)
IN
3526l G01
3526l G02
3526l G04
Efficiency vs Load Current and VIN
for VOUT = 5V (LTC3526L)
Minimum Load Resistance
During Start-Up vs VIN
Maximum Output Current vs VIN
100
90
1000
100
10
400
350
300
250
200
150
100
50
10000
1000
V
= 3.3V
OUT
V
OUT
= 3.3V
V
= 2.5V
OUT
80
V
= 1.8V
OUT
70
60
50
V
V
V
V
= 1.2V
= 2.4V
= 3.6V
= 4.2V
IN
IN
IN
IN
V
= 5V
OUT
40
30
20
10
0
1
100
PLOSS AT V = 1.2V
IN
0.1
0.01
PLOSS AT V = 2.4V
IN
PLOSS AT V = 3.6V
IN
PLOSS AT V = 4.2V
IN
L = 4.7µH
0
10
2.5 3.0
(V)
0.01
0.1
1
10
100
1000
0.5 1.0 1.5 2.0
3.5 4.0 4.5
0.65
0.75
0.85
0.95
(V)
1.05
1.15
LOAD CURRENT (mA)
V
IN
V
IN
3526l G03
3526l G05
3526l G06
3526lfc
ꢂ
LTC3526L/LTC3526LB
typicAl perForMAnce chArActeristics
Burst Mode Threshold Current
Burst Mode Threshold Current
vs VIN (LTC3526L)
Start-Up Delay Time vs VIN
vs VIN (LTC3526L)
100
90
80
70
60
50
40
30
20
10
0
30
25
20
15
10
5
30
V
C
= 1.8V
= 10µF
V
C
= 2.5V
= 10µF
OUT
OUT
OUT
OUT
LEAVE BURST
LEAVE BURST
25
L = 4.7µH
L = 4.7µH
20
15
ENTER BURST
ENTER BURST
10
5
0
0
1.0
2.0 2.5 3.0
(V)
3.5 4.0 4.5
1.5
1.25
1.5
(V)
1.0
1.25
(V)
1.5
1.0
1.75
2.0
V
V
V
IN
IN
IN
3526l G07
3526l G08a
3526l G08b
Burst Mode Threshold Current
vs VIN (LTC3526L)
Burst Mode Threshold Current
vs VIN (LTC3526L)
Oscillator Frequency Change
vs VOUT
40
35
30
25
20
15
10
5
50
40
30
20
10
0
3
2
1
0
NORMALIZED TO V
= 3.3V
V
C
= 3.3V
= 10µF
V
C
= 5V
OUT
OUT
OUT
OUT
OUT
= 10µF
LEAVE BURST
L = 4.7µH
L = 4.7µH
LEAVE BURST
ENTER BURST
ENTER BURST
–1
–2
–3
0
3.5
(V)
4.5
5.0
1.5 2.0
2.5 3.0
V
4.0
1.0
1.5
2.0
(V)
2.5
3.0
3.0
(V)
4.0
4.5
1.0 1.5
2.0 2.5
3.5
V
V
IN
OUT
IN
3526l G09
3526l G08c
3526l G08d
Oscillator Frequency Change
vs Temperature
RDS(ON) vs VOUT
RDS(ON) Change vs Temperature
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
0.35
0.30
1.3
1.2
1.1
1.0
0.9
0.8
0.7
10
8
NORMALIZED TO 25°C
NORMALIZED TO 25°C
6
4
2
PMOS
NMOS
(V)
0
–2
–4
–6
–8
–10
–50 –30 –10 10
30
50
70
90
–50 –30 –10 10
30
50
70
90
1.5
2.5 3.0 3.5
4.0 4.5 5.0
2.0
V
TEMPERATURE (°C)
TEMPERATURE (°C)
OUT
3526l G12
3526l G11
3526l G10
3526lfc
ꢃ
LTC3526L/LTC3526LB
typicAl perForMAnce chArActeristics
Burst Mode Quiesent Current
VFB vs Temperature
Start-Up Voltage vs Temperature
vs VOUT (LTC3526L)
0.80
0.75
0.70
0.65
0.60
0.55
0.50
10.0
0.50
0.25
NORMALIZED TO 25°C
9.5
9.0
8.5
8.0
7.5
7.0
1mA LOAD
0
–0.25
–0.50
–0.75
–1.00
NO LOAD
40 60
TEMPERATURE (°C)
–60 –40 –20
0
20
80 100
–50
0
25
50
75
100
3.5
(V)
5.0
25
1.5 2.0 2.5 3.0
4.0 4.5
TEMPERATURE (°C)
V
OUT
3526l G13
3526l G14
3526l G15
Fixed Frequency Switching
Waveform and VOUT Ripple
Burst Mode Waveforms
(LTC3526L)
VOUT and IIN During Soft-Start
V
SW PIN
2V/DIV
OUT
SW PIN
2V/DIV
1V/DIV
V
OUT
INPUT
CURRENT
0.2A/DIV
SHDN PIN
1V/DIV
20mV/DIV
V
OUT
AC-COUPLED
10mV/DIV
INDUCTOR
CURRENT
0.2A/DIV
AC-COUPLED
3526l G18
3526l G16
3526l G17
V
C
= 3.3V
= 10µF
200µs/DIV
V
V
C
= 1.2V
500ns/DIV
V
V
C
= 1.2V
IN
OUT
OUT
10µs/DIV
OUT
OUT
IN
= 3.3V AT 100mA
= 3.3V
= 10µF
OUT
OUT
= 10µF
Load Step Response (from Burst
Mode Operation) (LTC3526L)
Load Step Response
(Fixed Frequency)
V
V
OUT
OUT
100mV/DIV
100mV/DIV
AC-COUPLED
AC-COUPLED
LOAD
CURRENT
50mA/DIV
LOAD
CURRENT
50mA/DIV
3526l G19
3526l G20
V
V
= 3.6V
OUT
100µs/DIV
V
V
= 3.6V
OUT
100µs/DIV
IN
IN
= 5V
= 5V
20mA TO 170mA STEP
50mA TO 150mA STEP
C
= 10µF
C
= 10µF
OUT
OUT
3526lfc
ꢄ
LTC3526L/LTC3526LB
typicAl perForMAnce chArActeristics
Load Step Response
(Fixed Frequency)
Load Step Response (from Burst
Mode Operation) (LTC3526L)
V
OUT
V
OUT
100mV/DIV
100mV/DIV
AC-COUPLED
AC-COUPLED
LOAD
CURRENT
50mA/DIV
LOAD
CURRENT
50mA/DIV
3526l G21
3526l G22
V
V
= 1.2V
100µs/DIV
V
V
= 1.2V
50µs/DIV
IN
OUT
IN
OUT
= 3.3V
= 3.3V
50mA TO 100mA STEP
= 10µF
5mA TO 100mA STEP
= 10µF
C
C
OUT
OUT
pin Functions
SW(Pin1):ꢀSwitchꢀPin.ꢀConnectꢀinductorꢀbetweenꢀSWꢀandꢀ
SHDN (Pin 4):ꢀLogicꢀControlledꢀShutdownꢀInput.ꢀThereꢀ
isꢀanꢀinternalꢀ4MΩꢀpull-downꢀonꢀthisꢀpin.
V .ꢀKeepꢀPCBꢀtraceꢀlengthsꢀasꢀshortꢀandꢀwideꢀasꢀpossibleꢀ
IN
toꢀreduceꢀEMI.ꢀIfꢀtheꢀinductorꢀcurrentꢀfallsꢀtoꢀzeroꢀorꢀSHDNꢀ
ꢀ •ꢀSHDNꢀ=ꢀHigh:ꢀNormalꢀoperation
ꢀ •ꢀSHDNꢀ=ꢀLow:ꢀShutdown,ꢀquiescentꢀcurrentꢀ<ꢀ1µA
isꢀlow,ꢀanꢀinternalꢀanti-ringingꢀswitchꢀisꢀconnectedꢀfromꢀ
SWꢀtoꢀV ꢀtoꢀminimizeꢀEMI.
IN
FB (Pin 5):ꢀFeedbackꢀInputꢀtoꢀtheꢀg ꢀErrorꢀAmplifier.ꢀCon-
m
GND(Pin2,ExposedPadPin7):ꢀSignalꢀandꢀPowerꢀGround.ꢀ
ProvideꢀaꢀshortꢀdirectꢀPCBꢀpathꢀbetweenꢀGNDꢀandꢀtheꢀ
(–)ꢀsideꢀofꢀtheꢀinputꢀandꢀoutputꢀcapacitors.ꢀThe Exposed
Pad must be soldered to the PCB ground plane.ꢀItꢀservesꢀ
asꢀanꢀadditionalꢀgroundꢀconnectionꢀandꢀasꢀaꢀmeansꢀofꢀ
conductingꢀheatꢀawayꢀfromꢀtheꢀpackage.
nectꢀresistorꢀdividerꢀtapꢀtoꢀthisꢀpin.ꢀTheꢀtopꢀofꢀtheꢀdividerꢀ
connectsꢀtoꢀtheꢀoutputꢀcapacitor,ꢀtheꢀbottomꢀofꢀtheꢀdividerꢀ
connectsꢀtoꢀGND.ꢀReferringꢀtoꢀtheꢀBlockꢀDiagram,ꢀtheꢀoutputꢀ
voltageꢀcanꢀbeꢀadjustedꢀfromꢀ1.5Vꢀtoꢀ5.25Vꢀby:ꢀ
R2
R1
VOUT =1.195V • 1+
V (Pin 3):ꢀInputꢀSupplyꢀPin.ꢀConnectꢀaꢀminimumꢀofꢀ1µFꢀ
IN
ꢀ
ceramicꢀ decouplingꢀ capacitorꢀ fromꢀ thisꢀ pinꢀ toꢀ groundꢀ
V
(Pin6):ꢀOutputꢀvoltageꢀsenseꢀandꢀdrainꢀofꢀtheꢀinternalꢀ
OUT
usingꢀshortꢀdirectꢀPCBꢀtraces.
synchronousꢀrectifier.ꢀPCBꢀtraceꢀfromꢀV ꢀtoꢀtheꢀoutputꢀ
OUT
filterꢀcapacitorꢀ(4.7µFꢀminimum)ꢀshouldꢀbeꢀasꢀshortꢀandꢀ
3526lfc
ꢅ
LTC3526L/LTC3526LB
block DiAgrAM
L1
4.7µH
V
IN
0.8V
TO 5V
C
IN
2.2µF
3
1
V
SW
IN
V
OUT
V
SEL
WELL
SWITCH
V
BEST
V
B
V
OUT
V
OUT
FB
1.5V
6
5
TO 5.25V
ANTI-RING
GATE DRIVERS
AND
R2
R1
ANTI-CROSS
CONDUCTION
SHDN
C
OUT
SHUTDOWN
4
SHUTDOWN
+
–
4.7µF
I
ZERO
COMP
4M
SLOPE
COMP
I
PK
COMP
V
V
REF
REF
–
+
I
PK
UVLO
ERROR AMP
SLEEP COMP
I
ZERO
START-UP
V
+
–
REF
LOGIC
MODE
CLK
TSD
CONTROL
1MHz
OSC
CLAMP
WAKE
THERMAL
SHUTDOWN
C
SS
EXPOSED
PAD
GND
2
7
3526l BD
operAtion
(Refer to Block Diagram)
TheꢀLTC3526L/LTC3526LBꢀareꢀ1MHzꢀsynchronousꢀboostꢀ rangeꢀofꢀloadꢀcurrents.ꢀBurstꢀModeꢀoperationꢀmaintainsꢀ
convertersꢀhousedꢀinꢀaꢀ6-leadꢀ2mmꢀ×ꢀ2mmꢀDFNꢀpackage.ꢀ highꢀefficiencyꢀatꢀveryꢀlightꢀloads,ꢀreducingꢀtheꢀquiescentꢀ
Withꢀaꢀguaranteedꢀabilityꢀtoꢀstartꢀupꢀandꢀoperateꢀfromꢀinputsꢀ currentꢀtoꢀjustꢀ9µA.ꢀOperationꢀcanꢀbeꢀbestꢀunderstoodꢀbyꢀ
lessꢀthanꢀ0.8V,ꢀthisꢀdeviceꢀfeaturesꢀfixedꢀfrequency,ꢀcurrentꢀ referringꢀtoꢀtheꢀBlockꢀDiagram.
modeꢀPWMꢀcontrolꢀforꢀexceptionalꢀlineꢀandꢀloadꢀregula-
tion.ꢀTheꢀcurrentꢀmodeꢀarchitectureꢀwithꢀadaptiveꢀslopeꢀ
LOW VOLTAGE START-UP
compensationꢀprovidesꢀexcellentꢀtransientꢀloadꢀresponse,ꢀ
TheꢀLTC3526L/LTC3526LBꢀincludeꢀanꢀindependentꢀstart-
requiringꢀminimalꢀoutputꢀfiltering.ꢀInternalꢀsoft-startꢀandꢀ
upꢀoscillatorꢀdesignedꢀtoꢀstartꢀupꢀatꢀanꢀinputꢀvoltageꢀofꢀ
internalꢀloopꢀcompensationꢀsimplifiesꢀtheꢀdesignꢀprocessꢀ
0.68Vꢀ(typical).ꢀSoft-startꢀandꢀinrushꢀcurrentꢀlimitingꢀareꢀ
whileꢀminimizingꢀtheꢀnumberꢀofꢀexternalꢀcomponents.
providedꢀduringꢀstart-up,ꢀasꢀwellꢀasꢀnormalꢀmode.
WithꢀitsꢀlowꢀR ꢀandꢀlowꢀgateꢀchargeꢀinternalꢀN-chan-
DS(ON)
Whenꢀ eitherꢀ V ꢀ orꢀ V ꢀ exceedsꢀ 1.3Vꢀ typical,ꢀ theꢀ ICꢀ
IN
OUT
nelꢀMOSFETꢀswitchꢀandꢀP-channelꢀMOSFETꢀsynchronousꢀ
rectifier,ꢀtheꢀLTC3526Lꢀachievesꢀhighꢀefficiencyꢀoverꢀaꢀwideꢀ
entersꢀnormalꢀoperatingꢀmode.ꢀWhenꢀtheꢀoutputꢀvoltageꢀ
3526lfc
ꢆ
LTC3526L/LTC3526LB
operAtion
(Refer to Block Diagram)
exceedsꢀ theꢀ inputꢀ byꢀ 0.24V,ꢀ theꢀ ICꢀ powersꢀ itselfꢀ fromꢀ
LTC3526L/LTC3526LB
4M
LTC3526L/LTC3526LB
4M
V
IN
V
ꢀinsteadꢀofꢀV .ꢀAtꢀthisꢀpointꢀtheꢀinternalꢀcircuitryꢀhasꢀ
OUT
IN
noꢀdependencyꢀonꢀtheꢀV ꢀinputꢀvoltage,ꢀeliminatingꢀtheꢀ
30ꢀ
30ꢀ
IN
SHDN
SHDN
requirementꢀforꢀaꢀlargeꢀinputꢀcapacitor.ꢀTheꢀinputꢀvoltageꢀ
canꢀdropꢀasꢀlowꢀasꢀ0.5V.ꢀTheꢀlimitingꢀfactorꢀforꢀtheꢀap-
plicationꢀbecomesꢀtheꢀavailabilityꢀofꢀtheꢀpowerꢀsourceꢀtoꢀ
supplyꢀsufficientꢀenergyꢀtoꢀtheꢀoutputꢀatꢀlowꢀvoltages,ꢀandꢀ
maximumꢀdutyꢀcycle,ꢀwhichꢀisꢀclampedꢀatꢀ90%ꢀtypical.ꢀ
Noteꢀthatꢀatꢀlowꢀinputꢀvoltages,ꢀsmallꢀvoltageꢀdropsꢀdueꢀ
toꢀseriesꢀresistanceꢀbecomeꢀcritical,ꢀandꢀgreatlyꢀlimitꢀtheꢀ
powerꢀdeliveryꢀcapabilityꢀofꢀtheꢀconverter.
V
CNTRL
R
ZETEX ZC2811E
1M
V
CNTRL
1M
R > (V
/(V + 0.4) – 1)MΩ
CNTRL IN
3526l F01
Figure 1. Recommended Shutdown Circuits when Driving
SHDN above VIN
Error Amplifier
LOW NOISE FIXED FREQUENCY OPERATION
Soft-Start
Theꢀpositiveꢀinputꢀofꢀtheꢀtransconductanceꢀerrorꢀamplifierꢀ
isꢀinternallyꢀconnectedꢀtoꢀtheꢀ1.195Vꢀreferenceꢀandꢀtheꢀ
negativeꢀinputꢀisꢀconnectedꢀtoꢀFB.ꢀClampsꢀlimitꢀtheꢀmini-
mumꢀandꢀmaximumꢀerrorꢀampꢀoutputꢀvoltageꢀforꢀimprovedꢀ
large-signalꢀtransientꢀresponse.ꢀPowerꢀconverterꢀcontrolꢀ
loopꢀ compensationꢀ isꢀ providedꢀ internally.ꢀ Anꢀ externalꢀ
Theꢀ LTC3526L/LTC3526LBꢀ containꢀ internalꢀ circuitryꢀ toꢀ
provideꢀsoft-startꢀoperation.ꢀTheꢀsoft-startꢀcircuitryꢀslowlyꢀ
rampsꢀtheꢀpeakꢀinductorꢀcurrentꢀfromꢀzeroꢀtoꢀitsꢀpeakꢀvalueꢀ
ofꢀ750mAꢀ(typical)ꢀinꢀapproximatelyꢀ0.5ms,ꢀallowingꢀstart-
upꢀintoꢀheavyꢀloads.ꢀTheꢀsoft-startꢀcircuitryꢀisꢀresetꢀinꢀtheꢀ
eventꢀofꢀaꢀshutdownꢀcommandꢀorꢀaꢀthermalꢀshutdown.
resistiveꢀvoltageꢀdividerꢀfromꢀV ꢀtoꢀgroundꢀprogramsꢀ
OUT
theꢀoutputꢀvoltageꢀviaꢀFBꢀfromꢀ1.5Vꢀtoꢀ5.25V.
R2
R1
VOUT =1.195V • 1+
Oscillator
ꢀ
Anꢀ internalꢀ oscillatorꢀ setsꢀ theꢀ switchingꢀ frequencyꢀ toꢀ
1MHz.
Current Sensing
Losslessꢀcurrentꢀsensingꢀconvertsꢀtheꢀpeakꢀcurrentꢀsignalꢀofꢀ
theꢀN-channelꢀMOSFETꢀswitchꢀintoꢀaꢀvoltageꢀthatꢀisꢀsummedꢀ
withꢀtheꢀinternalꢀslopeꢀcompensation.ꢀTheꢀsummedꢀsignalꢀ
isꢀcomparedꢀtoꢀtheꢀerrorꢀamplifierꢀoutputꢀtoꢀprovideꢀaꢀpeakꢀ
currentꢀcontrolꢀcommandꢀforꢀtheꢀPWM.
Shutdown
Shutdownꢀ isꢀ accomplishedꢀ byꢀ pullingꢀ theꢀ SHDNꢀ pinꢀ
belowꢀ0.3VꢀandꢀenabledꢀbyꢀpullingꢀtheꢀSHDNꢀpinꢀaboveꢀ
0.8V.ꢀAlthoughꢀSHDNꢀcanꢀbeꢀdrivenꢀaboveꢀV ꢀorꢀV
ꢀ
IN
OUT
(upꢀtoꢀtheꢀabsoluteꢀmaximumꢀrating)ꢀwithoutꢀdamage,ꢀ
theꢀLTC3526L/LTC3526LBꢀhaveꢀaꢀproprietaryꢀtestꢀmodeꢀ
thatꢀmayꢀbeꢀengagedꢀifꢀSHDNꢀisꢀheldꢀinꢀtheꢀrangeꢀofꢀ0.5Vꢀ
Current Limit
Theꢀ currentꢀ limitꢀ comparatorꢀ shutsꢀ offꢀ theꢀ N-channelꢀ
MOSFETꢀswitchꢀonceꢀitsꢀthresholdꢀisꢀreached.ꢀTheꢀcur-
rentꢀlimitꢀcomparatorꢀdelayꢀtoꢀoutputꢀisꢀtypicallyꢀ60ns.ꢀ
Peakꢀswitchꢀcurrentꢀisꢀlimitedꢀtoꢀapproximatelyꢀ750mA,ꢀ
independentꢀofꢀinputꢀorꢀoutputꢀvoltage,ꢀunlessꢀV ꢀfallsꢀ
belowꢀ0.7V,ꢀinꢀwhichꢀcaseꢀtheꢀcurrentꢀlimitꢀisꢀcutꢀinꢀhalf.
toꢀ1VꢀhigherꢀthanꢀtheꢀgreaterꢀofꢀV ꢀorꢀV .ꢀIfꢀtheꢀtestꢀ
IN
OUT
modeꢀisꢀengaged,ꢀnormalꢀPWMꢀswitchingꢀactionꢀisꢀinter-
rupted,ꢀwhichꢀcanꢀcauseꢀundesirableꢀoperationꢀinꢀsomeꢀ
applications.ꢀTherefore,ꢀinꢀapplicationsꢀwhereꢀSHDNꢀmayꢀ
OUT
beꢀdrivenꢀaboveꢀV ,ꢀaꢀresistorꢀdividerꢀorꢀotherꢀmeansꢀ
IN
mustꢀbeꢀemployedꢀtoꢀkeepꢀtheꢀSHDNꢀvoltageꢀbelowꢀ(V ꢀ
IN
Zero Current Comparator
+ꢀ0.4V)ꢀtoꢀpreventꢀtheꢀpossibilityꢀofꢀtheꢀtestꢀmodeꢀbeingꢀ
engaged.ꢀPleaseꢀreferꢀtoꢀFigureꢀ1ꢀforꢀtwoꢀpossibleꢀimple-
mentations.
Theꢀzeroꢀcurrentꢀcomparatorꢀmonitorsꢀtheꢀinductorꢀcur-
rentꢀtoꢀtheꢀoutputꢀandꢀshutsꢀoffꢀtheꢀsynchronousꢀrectifierꢀ
3526lfc
ꢇ
LTC3526L/LTC3526LB
operAtion
(Refer to Block Diagram)
whenꢀthisꢀcurrentꢀreducesꢀtoꢀapproximatelyꢀ30mA.ꢀThisꢀ Burst Mode OPERATION
preventsꢀtheꢀinductorꢀcurrentꢀfromꢀreversingꢀinꢀpolarity,ꢀ
TheꢀLTC3526LꢀwillꢀenterꢀBurstꢀModeꢀoperationꢀatꢀlightꢀloadꢀ
improvingꢀefficiencyꢀatꢀlightꢀloads.
currentꢀandꢀreturnꢀtoꢀfixedꢀfrequencyꢀPWMꢀmodeꢀwhenꢀtheꢀ
loadꢀincreases.ꢀReferꢀtoꢀtheꢀTypicalꢀPerformanceꢀCharacter-
isticsꢀtoꢀseeꢀtheꢀoutputꢀloadꢀBurstꢀModeꢀthresholdꢀcurrentꢀ
Synchronous Rectifier
Toꢀ controlꢀ inrushꢀ currentꢀ andꢀ toꢀ preventꢀ theꢀ inductorꢀ
currentꢀfromꢀrunningꢀawayꢀwhenꢀV ꢀisꢀcloseꢀtoꢀV ,ꢀtheꢀ
vsꢀV .ꢀTheꢀloadꢀcurrentꢀatꢀwhichꢀBurstꢀModeꢀoperationꢀisꢀ
IN
enteredꢀcanꢀbeꢀchangedꢀbyꢀadjustingꢀtheꢀinductorꢀvalue.ꢀ
Raisingꢀtheꢀinductorꢀvalueꢀwillꢀlowerꢀtheꢀloadꢀcurrentꢀatꢀ
whichꢀBurstꢀModeꢀoperationꢀisꢀentered.
OUT
IN
P-channelꢀMOSFETꢀsynchronousꢀrectifierꢀisꢀonlyꢀenabledꢀ
whenꢀV ꢀ>ꢀ(V ꢀ+ꢀ0.24V).
OUT
IN
InꢀBurstꢀModeꢀoperation,ꢀtheꢀLTC3526Lꢀstillꢀswitchesꢀatꢀaꢀ
fixedꢀfrequencyꢀofꢀ1MHz,ꢀusingꢀtheꢀsameꢀerrorꢀamplifierꢀ
andꢀloopꢀcompensationꢀforꢀpeakꢀcurrentꢀmodeꢀcontrol.ꢀ
Thisꢀ controlꢀ methodꢀ eliminatesꢀ anyꢀ outputꢀ transientꢀ
whenꢀswitchingꢀbetweenꢀmodes.ꢀInꢀBurstꢀModeꢀopera-
tion,ꢀenergyꢀisꢀdeliveredꢀtoꢀtheꢀoutputꢀuntilꢀitꢀreachesꢀtheꢀ
nominalꢀregulationꢀvalue,ꢀthenꢀtheꢀLTC3526Lꢀtransitionsꢀ
toꢀsleepꢀmodeꢀwhereꢀtheꢀoutputsꢀareꢀoffꢀandꢀtheꢀLTC3526Lꢀ
Anti-Ringing Control
Theꢀanti-ringꢀcircuitꢀconnectsꢀaꢀresistorꢀacrossꢀtheꢀin-
ductorꢀtoꢀpreventꢀhighꢀfrequencyꢀringingꢀonꢀtheꢀSWꢀpinꢀ
duringꢀdiscontinuousꢀcurrentꢀmodeꢀoperation.ꢀAlthoughꢀ
theꢀringingꢀofꢀtheꢀresonantꢀcircuitꢀformedꢀbyꢀLꢀandꢀC
(capacitanceꢀonꢀSWꢀpin)ꢀisꢀlowꢀenergy,ꢀitꢀcanꢀcauseꢀEMIꢀ
radiation.
ꢀ
SW
consumesꢀonlyꢀ9µAꢀofꢀquiescentꢀcurrentꢀfromꢀV .ꢀWhenꢀ
OUT
Output Disconnect
theꢀoutputꢀvoltageꢀdroopsꢀslightly,ꢀswitchingꢀresumes.ꢀ
TheꢀLTC3526L/LTC3526LBꢀareꢀdesignedꢀtoꢀallowꢀtrueꢀoutputꢀ Thisꢀmaximizesꢀefficiencyꢀatꢀveryꢀlightꢀloadsꢀbyꢀminimizingꢀ
disconnectꢀbyꢀeliminatingꢀbodyꢀdiodeꢀconductionꢀofꢀtheꢀ switchingꢀandꢀquiescentꢀlosses.ꢀBurstꢀModeꢀoutputꢀvoltageꢀ
internalꢀP-channelꢀMOSFETꢀrectifier.ꢀThisꢀallowsꢀforꢀV
ꢀ
ripple,ꢀwhichꢀisꢀtypicallyꢀ1%ꢀpeak-to-peak,ꢀcanꢀbeꢀreducedꢀ
OUT
toꢀgoꢀtoꢀzeroꢀvoltsꢀduringꢀshutdown,ꢀdrawingꢀnoꢀcurrentꢀ byꢀusingꢀmoreꢀoutputꢀcapacitanceꢀ(10µFꢀorꢀgreater),ꢀorꢀ
fromꢀtheꢀinputꢀsource.ꢀItꢀalsoꢀallowsꢀforꢀinrushꢀcurrentꢀ withꢀaꢀsmallꢀcapacitorꢀ(10pFꢀtoꢀ50pF)ꢀconnectedꢀbetweenꢀ
limitingꢀatꢀturn-on,ꢀminimizingꢀsurgeꢀcurrentsꢀseenꢀbyꢀtheꢀ
inputꢀsupply.ꢀNoteꢀthatꢀtoꢀobtainꢀtheꢀadvantagesꢀofꢀoutputꢀ
disconnect,ꢀthereꢀmustꢀnotꢀbeꢀanꢀexternalꢀSchottkyꢀdiodeꢀ
V
ꢀandꢀFB.
OUT
Asꢀtheꢀloadꢀcurrentꢀincreases,ꢀtheꢀLTC3526Lꢀwillꢀauto-
maticallyꢀleaveꢀBurstꢀModeꢀoperation.ꢀNoteꢀthatꢀlargerꢀ
outputꢀ capacitorꢀ valuesꢀ mayꢀ causeꢀ thisꢀ transitionꢀ toꢀ
occurꢀatꢀlighterꢀloads.ꢀOnceꢀtheꢀLTC3526LꢀhasꢀleftꢀBurstꢀ
Modeꢀoperationꢀandꢀreturnedꢀtoꢀnormalꢀoperation,ꢀitꢀwillꢀ
remainꢀthereꢀuntilꢀtheꢀoutputꢀloadꢀisꢀreducedꢀbelowꢀtheꢀ
burstꢀthresholdꢀcurrent.
connectedꢀbetweenꢀSWꢀandꢀV .ꢀTheꢀoutputꢀdisconnectꢀ
OUT
featureꢀalsoꢀallowsꢀV ꢀtoꢀbeꢀpulledꢀhigh,ꢀwithoutꢀanyꢀ
OUT
reverseꢀcurrentꢀintoꢀaꢀbatteryꢀconnectedꢀtoꢀV .
IN
Thermal Shutdown
Ifꢀtheꢀdieꢀtemperatureꢀexceedsꢀ160°C,ꢀtheꢀLTC3526L/LT-
C3526LBꢀwillꢀgoꢀintoꢀthermalꢀshutdown.ꢀAllꢀswitchesꢀwillꢀ
beꢀoffꢀandꢀtheꢀsoft-startꢀcapacitorꢀwillꢀbeꢀdischarged.ꢀTheꢀ
deviceꢀwillꢀbeꢀenabledꢀagainꢀwhenꢀtheꢀdieꢀtemperatureꢀ TheꢀLTC3526LBꢀfeaturesꢀcontinuousꢀPWMꢀoperationꢀatꢀ
dropsꢀbyꢀaboutꢀ15°C.
BurstꢀModeꢀoperationꢀisꢀinhibitedꢀduringꢀstart-upꢀandꢀsoft-
startꢀandꢀuntilꢀV ꢀisꢀatꢀleastꢀ0.24VꢀgreaterꢀthanꢀV .
OUT
IN
1MHz.ꢀ Atꢀ veryꢀ lightꢀ loads,ꢀ theꢀ LTC3526LBꢀ willꢀ exhibitꢀ
pulse-skipꢀoperation.
3526lfc
ꢈ
LTC3526L/LTC3526LB
ApplicAtions inForMAtion
V > V
OPERATION
COMPONENT SELECTION
Inductor Selection
IN
OUT
TheꢀLTC3526L/LTC3526LBꢀwillꢀmaintainꢀvoltageꢀregulationꢀ
evenꢀwhenꢀtheꢀinputꢀvoltageꢀisꢀaboveꢀtheꢀdesiredꢀoutputꢀ
voltage.ꢀNoteꢀthatꢀtheꢀefficiencyꢀisꢀmuchꢀlowerꢀinꢀthisꢀmode,ꢀ
andꢀtheꢀmaximumꢀoutputꢀcurrentꢀcapabilityꢀwillꢀbeꢀless.ꢀ
ReferꢀtoꢀtheꢀTypicalꢀPerformanceꢀCharacteristics.
TheꢀLTC3526L/LTC3526LBꢀcanꢀutilizeꢀsmallꢀsurfaceꢀmountꢀ
chipꢀinductorsꢀdueꢀtoꢀtheirꢀfastꢀ1MHzꢀswitchingꢀfrequency.ꢀ
Inductorꢀvaluesꢀbetweenꢀ3.3µHꢀandꢀ6.8µHꢀareꢀsuitableꢀforꢀ
mostꢀapplications.ꢀLargerꢀvaluesꢀofꢀinductanceꢀwillꢀallowꢀ
slightlyꢀgreaterꢀoutputꢀcurrentꢀcapabilityꢀ(andꢀlowerꢀtheꢀ
BurstꢀModeꢀthreshold)ꢀbyꢀreducingꢀtheꢀinductorꢀrippleꢀcur-
rent.ꢀIncreasingꢀtheꢀinductanceꢀaboveꢀ10µHꢀwillꢀincreaseꢀ
componentꢀ sizeꢀ whileꢀ providingꢀ littleꢀ improvementꢀ inꢀ
outputꢀcurrentꢀcapability.
SHORT-CIRCUIT PROTECTION
TheꢀLTC3526L/LTC3526LBꢀoutputꢀdisconnectꢀfeatureꢀal-
lowsꢀoutputꢀshortꢀcircuitꢀwhileꢀmaintainingꢀaꢀmaximumꢀ
internallyꢀsetꢀcurrentꢀlimit.ꢀToꢀreduceꢀpowerꢀdissipationꢀ
underꢀshort-circuitꢀconditions,ꢀtheꢀpeakꢀswitchꢀcurrentꢀ
limitꢀisꢀreducedꢀtoꢀ400mAꢀ(typical).
Theꢀminimumꢀinductanceꢀvalueꢀisꢀgivenꢀby:
V
• VOUT(MAX) – V
(
)
IN(MIN)
IN(MIN)
L >
SCHOTTKY DIODE
Ripple• VOUT(MAX)
ꢀ
Althoughꢀnotꢀrecommended,ꢀaddingꢀaꢀSchottkyꢀdiodeꢀfromꢀ
where:
SWꢀtoꢀV ꢀwillꢀimproveꢀefficiencyꢀbyꢀaboutꢀ2%.ꢀNoteꢀ
OUT
thatꢀthisꢀdefeatsꢀtheꢀoutputꢀdisconnectꢀandꢀshort-circuitꢀ
Rippleꢀ=ꢀAllowableꢀinductorꢀcurrentꢀrippleꢀ(ampsꢀpeak-
peak)
protectionꢀfeatures.
V
V
ꢀ=ꢀMinimumꢀinputꢀvoltage
IN(MIN)
PCB LAYOUT GUIDELINES
ꢀ=ꢀMaximumꢀoutputꢀvoltage
OUT(MAX)
TheꢀhighꢀspeedꢀoperationꢀofꢀtheꢀLTC3526L/LTC3526LBꢀ
demandsꢀ carefulꢀ attentionꢀ toꢀ boardꢀ layout.ꢀ Aꢀ carelessꢀ
layoutꢀwillꢀresultꢀinꢀreducedꢀperformance.ꢀFigureꢀ2ꢀshowsꢀ
theꢀrecommendedꢀcomponentꢀplacement.ꢀAꢀlargeꢀgroundꢀ
pinꢀcopperꢀareaꢀwillꢀhelpꢀtoꢀlowerꢀtheꢀdieꢀtemperature.ꢀAꢀ
multilayerꢀboardꢀwithꢀaꢀseparateꢀgroundꢀplaneꢀisꢀideal,ꢀbutꢀ
notꢀabsolutelyꢀnecessary.
Theꢀinductorꢀcurrentꢀrippleꢀisꢀtypicallyꢀsetꢀforꢀ20%ꢀtoꢀ
40%ꢀofꢀtheꢀmaximumꢀinductorꢀcurrent.ꢀHighꢀfrequencyꢀ
ferriteꢀcoreꢀinductorꢀmaterialsꢀreduceꢀfrequencyꢀdependentꢀ
powerꢀlossesꢀcomparedꢀtoꢀcheaperꢀpowderedꢀironꢀtypes,ꢀ
improvingꢀefficiency.ꢀTheꢀinductorꢀshouldꢀhaveꢀlowꢀESRꢀ
(seriesꢀresistanceꢀofꢀtheꢀwindings)ꢀtoꢀreduceꢀtheꢀI2Rꢀpowerꢀ
LTC3526L
SW
V
OUT
1
2
3
6
5
4
MINIMIZE
TRACE ON FB
AND SW
GND
FB
V
SHDN
IN
+
V
IN
MULTIPLE VIAS
TO GROUND PLANE
3526l F02
Figure 2. Recommended Component Placement for Single Layer Board
3526lfc
ꢀ0
LTC3526L/LTC3526LB
ApplicAtions inForMAtion
losses,ꢀandꢀmustꢀbeꢀableꢀtoꢀsupportꢀtheꢀpeakꢀinductorꢀ
currentꢀ withoutꢀ saturating.ꢀ Moldedꢀ chokesꢀ andꢀ someꢀ
chipꢀinductorsꢀusuallyꢀdoꢀnotꢀhaveꢀenoughꢀcoreꢀareaꢀtoꢀ
supportꢀtheꢀpeakꢀinductorꢀcurrentꢀofꢀ750mAꢀseenꢀonꢀtheꢀ
LTC3526L/LTC3526LB.ꢀToꢀminimizeꢀradiatedꢀnoise,ꢀuseꢀaꢀ
shieldedꢀinductor.ꢀSeeꢀTableꢀ1ꢀforꢀsuggestedꢀcomponentsꢀ
andꢀsuppliers.
Output and Input Capacitor Selection
LowꢀESRꢀ(equivalentꢀseriesꢀresistance)ꢀcapacitorsꢀshouldꢀ
beꢀusedꢀtoꢀminimizeꢀtheꢀoutputꢀvoltageꢀripple.ꢀMultilayerꢀ
ceramicꢀcapacitorsꢀareꢀanꢀexcellentꢀchoiceꢀasꢀtheyꢀhaveꢀ
extremelyꢀlowꢀESRꢀandꢀareꢀavailableꢀinꢀsmallꢀfootprints.ꢀAꢀ
4.7µFꢀtoꢀ10µFꢀoutputꢀcapacitorꢀisꢀsufficientꢀforꢀmostꢀap-
plications.ꢀLargerꢀvaluesꢀmayꢀbeꢀusedꢀtoꢀobtainꢀextremelyꢀ
lowꢀoutputꢀvoltageꢀrippleꢀandꢀimproveꢀtransientꢀresponse.ꢀ
X5RꢀandꢀX7Rꢀdielectricꢀmaterialsꢀareꢀpreferredꢀforꢀtheirꢀ
abilityꢀ toꢀ maintainꢀ capacitanceꢀ overꢀ wideꢀ voltageꢀ andꢀ
temperatureꢀranges.ꢀY5Vꢀtypesꢀshouldꢀnotꢀbeꢀused.
Table 1. Recommended Inductors
VENDOR
PART/STYLE
Coilcraftꢀ
(847)ꢀ639-6400ꢀ
www.coilcraft.com
LPO4815ꢀ
LPS4012,ꢀLPS4018ꢀ
MSS5131ꢀ
MSS4020ꢀ
Theꢀ internalꢀ loopꢀ compensationꢀ ofꢀ theꢀ LTC3526L/LT-
C3526LBꢀareꢀdesignedꢀtoꢀbeꢀstableꢀwithꢀoutputꢀcapaci-
torꢀvaluesꢀofꢀ4.7µFꢀorꢀgreaterꢀ(withoutꢀtheꢀneedꢀforꢀanyꢀ
externalꢀ seriesꢀ resistor).ꢀ Althoughꢀ ceramicꢀ capacitorsꢀ
areꢀrecommended,ꢀlowꢀESRꢀtantalumꢀcapacitorsꢀmayꢀbeꢀ
usedꢀasꢀwell.
MOS6020ꢀ
ME3220ꢀ
DS1605,ꢀDO1608
Coiltronicsꢀ
www.cooperet.com
SD10,ꢀSD12,ꢀSD14,ꢀSD18,ꢀSD20,ꢀ
SD52,ꢀSD3114,ꢀSD3118
FDKꢀ
(408)ꢀ432-8331ꢀ
www.fdk.com
MIP3226D4R7M,ꢀMIP3226D3R3Mꢀ
MIPF2520D4R7ꢀ
MIPWT3226D3R0
Aꢀsmallꢀceramicꢀcapacitorꢀinꢀparallelꢀwithꢀaꢀlargerꢀtantalumꢀ
capacitorꢀmayꢀbeꢀusedꢀinꢀdemandingꢀapplicationsꢀthatꢀhaveꢀ
largeꢀloadꢀtransients.ꢀAnotherꢀmethodꢀofꢀimprovingꢀtheꢀ
transientꢀresponseꢀisꢀtoꢀaddꢀaꢀsmallꢀfeed-forwardꢀcapacitorꢀ
acrossꢀtheꢀtopꢀresistorꢀofꢀtheꢀfeedbackꢀdividerꢀ(fromꢀV
toꢀFB).ꢀAꢀtypicalꢀvalueꢀofꢀ22pFꢀwillꢀgenerallyꢀsuffice.
Murataꢀ
(714)ꢀ852-2001ꢀ
www.murata.com
LQH43Cꢀ
LQH32Cꢀ(-53ꢀseries)ꢀ
301015
Sumidaꢀ
(847)ꢀ956-0666ꢀ
www.sumida.com
CDRH5D18ꢀ
CDRH2D14ꢀ
CDRH3D16ꢀ
CDRH3D11ꢀ
CR43ꢀ
ꢀ
OUT
LowꢀESRꢀinputꢀcapacitorsꢀreduceꢀinputꢀswitchingꢀnoiseꢀ
andꢀreduceꢀtheꢀpeakꢀcurrentꢀdrawnꢀfromꢀtheꢀbattery.ꢀItꢀ
followsꢀthatꢀceramicꢀcapacitorsꢀareꢀalsoꢀaꢀgoodꢀchoiceꢀ
forꢀinputꢀdecouplingꢀandꢀshouldꢀbeꢀlocatedꢀasꢀcloseꢀasꢀ
possibleꢀtoꢀtheꢀdevice.ꢀAꢀ2.2µFꢀinputꢀcapacitorꢀisꢀsufficientꢀ
forꢀ mostꢀ applications,ꢀ althoughꢀ largerꢀ valuesꢀ mayꢀ beꢀ
usedꢀwithoutꢀlimitations.ꢀTableꢀ2ꢀshowsꢀaꢀlistꢀofꢀseveralꢀ
ceramicꢀcapacitorꢀmanufacturers.ꢀConsultꢀtheꢀmanufactur-
ersꢀdirectlyꢀforꢀdetailedꢀinformationꢀonꢀtheirꢀselectionꢀofꢀ
ceramicꢀcapacitors.
CMD4D06-4R7MCꢀ
CMD4D06-3R3MC
Taiyo-Yudenꢀ
www.t-yuden.com
NP03SBꢀ
NR3015Tꢀ
NR3012T
TDKꢀ
VLPꢀ
VLF,ꢀVLCF
(847)ꢀ803-6100ꢀ
www.component.tdk.com
Tokoꢀ
(408)ꢀ432-8282ꢀ
www.tokoam.com
D412Cꢀ
D518LCꢀ
D52LCꢀ
D62LCB
Wurthꢀ
(201)ꢀ785-8800ꢀ
www.we-online.com
WE-TPCꢀtypeꢀS,ꢀM
Table 2. Capacitor Vendor Information
SUPPLIER
AVX
PHONE
WEBSITE
(803)ꢀ448-9411
(714)ꢀ852-2001
(408)ꢀ573-4150
(847)ꢀ803-6100
(408)ꢀ544-5200
www.avxcorp.com
www.murata.com
www.t-yuden.com
www.component.tdk.com
www.sem.samsung.com
Murata
Taiyo-Yuden
TDK
Samsung
3526lfc
ꢀꢀ
LTC3526L/LTC3526LB
typicAl ApplicAtions
1-Cell to 1.8V Converter with <1mm Maximum Height
100
90
V
= 1.8V
OUT
4.7µH*
80
SW
70
V
OUT
V
IN
1.8V
V
IN
V
OUT
60
50
0.8V TO 1.6V
150mA
1µF
LTC3526L
SHDN FB
GND
511k
1M
10µF**
OFF ON
40
30
20
10
0
3526l TA02a
V
V
V
= 1.5V
= 1.2V
= 0.9V
IN
IN
IN
*FDK MIP3226D4R7M
**MURATA GRM219R60J106KE19D
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA02b
1-Cell to 2.85V Converter
100
V
= 2.85V
OUT
90
80
70
4.7µH*
SW
V
OUT
V
IN
2.85V
60
50
V
IN
V
OUT
0.8V TO 1.6V
100mA
1µF
LTC3526L
SHDN FB
GND
1.4M
1M
40
30
20
10
0
10µF
OFF ON
3526l TA03a
V
V
V
= 1.5V
= 1.2V
= 0.9V
IN
IN
IN
*SUMIDA CDRH3D16-4R7
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA03b
1-Cell to 3.3V
100
V
= 3.3V
OUT
4.7µH*
SW
90
80
70
V
OUT
V
IN
3.3V
V
IN
V
OUT
60
50
0.8V TO 1.6V
75mA
1.78M
22pF
1µF
LTC3526L
SHDN FB
GND
10µF
40
30
20
10
0
OFF ON
1M
3526l TA04a
V
V
V
= 1.5V
= 1.2V
= 0.9V
IN
IN
IN
*TAIYO-YUDEN NP03SB4R7M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA04b
3526lfc
ꢀꢁ
LTC3526L/LTC3526LB
typicAl ApplicAtions
2-Cell to 3.3V
100
90
V
= 3.3V
OUT
4.7µH*
80
70
SW
V
OUT
V
IN
3.3V
V
IN
V
OUT
60
50
1.6V TO 3.2V
200mA
1µF
LTC3526L
SHDN FB
GND
1.78M
1M
40
30
20
10
0
4.7µF
OFF ON
3526l TA05a
V
V
V
= 3.0V
= 2.4V
= 1.8V
IN
IN
IN
*TAIYO-YUDEN NP03SB4R7M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA05b
2-Cell to 5V
100
V
= 5V
OUT
90
80
70
6.8µH*
SW
V
OUT
V
IN
5V
V
IN
V
OUT
60
50
1.6V TO 3.2V
150mA
1µF
LTC3526L
SHDN FB
GND
3.24M
22pF
40
30
20
10
0
10µF
OFF ON
1.02M
3526l TA06a
V
V
V
= 3.0V
= 2.4V
= 1.8V
IN
IN
IN
*TAIYO-YUDEN NP03SB6R8M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA06b
Li-Ion to 5V
100
V
= 5V
OUT
6.8µH*
SW
90
80
70
V
OUT
V
IN
5V
V
IN
V
OUT
60
50
2.7V TO 4.3V
200mA
1µF
LTC3526L
SHDN FB
GND
3.24M
1.02M
22pF
10µF
40
30
20
10
0
OFF ON
3526l TA08a
V
V
V
= 4.2V
= 3.6V
= 3.0V
IN
IN
IN
*TAIYO-YUDEN NP03SB6R8M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
3526l TA08b
3526lfc
ꢀꢂ
LTC3526L/LTC3526LB
pAckAge Description
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(ReferenceꢀLTCꢀDWGꢀ#ꢀ05-08-1703ꢀRevꢀB)
0.70 p0.05
2.55 p0.05
0.61 p0.05
1.15 p0.05
(2 SIDES)
PACKAGE
OUTLINE
0.25 p 0.05
0.50 BSC
1.42 p0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.125
TYP
0.56 p 0.05
(2 SIDES)
0.40 p 0.10
4
6
2.00 p0.10
PIN 1 NOTCH
(4 SIDES)
R = 0.20 OR
0.25 s 45o
CHAMFER
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
(DC6) DFN REV B 1309
R = 0.05
TYP
3
1
0.25 p 0.05
0.50 BSC
0.75 p0.05
0.200 REF
1.37 p0.05
(2 SIDES)
BOTTOM VIEW—EXPOSED PAD
0.00 – 0.05
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
3526lfc
ꢀꢃ
LTC3526L/LTC3526LB
revision history (Revision history begins at Rev C)
REV
DATE
DESCRIPTION
PAGE NUMBER
C
9/10
2
3
Updatedꢀθ ꢀonꢀPinꢀConfiguration
UpdatedꢀNoteꢀ6
JA
8
UpdatedꢀShutdownꢀsection
UpdatedꢀRelatedꢀParts
16
3526lfc
Information furnished by Linear Technology ꢀorporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology ꢀorporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
ꢀꢄ
LTC3526L/LTC3526LB
typicAl ApplicAtion
3.3V Converter with Output OR’d with 5V USB Input
MBR120ESFT
5V USB
4.7µH
V
OUT
LDO
3.3V/5V
USB
SW
V
BATT
V
IN
V
OUT
1.8V TO 3.2V
1.78M
1M
1µF
LTC3526L
SHDN FB
GND
DC/DC
10µF
OFF ON
3526l TA07a
relAteD pArts
PART NUMBER
DESCRIPTION
COMMENTS
94%ꢀEfficiencyꢀVIN:ꢀ0.85Vꢀtoꢀ5V,ꢀVOUT(MAX)ꢀ=ꢀ5.25V,ꢀIQꢀ=ꢀ9µA,ꢀꢀ
SDꢀ<ꢀ1µA,ꢀ2mm × 2mm DFN-6 Package
LTC3526/LTC3526Bꢀ
500mA,ꢀ1MHz/2.2MHz,ꢀSynchronousꢀStep-UpꢀDC/DCꢀ
ConvertersꢀwithꢀOutputꢀDisconnect
LTC3526-2/LTC3526B-2ꢀ
LTC3526L-2/LTC3526LB-2
I
LTC3525L-3
400mAꢀMicropowerꢀSynchronousꢀStep-UpꢀDC/DCꢀ
ConverterꢀwithꢀOutputꢀDisconnect
93%ꢀEfficiencyꢀVIN:ꢀ0.88Vꢀtoꢀ4.5V,ꢀVOUTꢀ=ꢀ3V,ꢀIQꢀ=ꢀ7µA,ꢀꢀ
SDꢀ<ꢀ1µA,ꢀSC-70ꢀPackage
I
LTC3525-3ꢀ
LTC3525-3.3ꢀ
LTC3525-5
400mAꢀMicropowerꢀSynchronousꢀStep-UpꢀDC/DCꢀ
ConverterꢀwithꢀOutputꢀDisconnect
95%ꢀEfficiencyꢀVIN:ꢀ1Vꢀtoꢀ4.5V,ꢀVOUT(MAX)ꢀ=ꢀ3.3Vꢀorꢀ5V,ꢀIQꢀ=ꢀ7µA,ꢀꢀ
SDꢀ<ꢀ1µA,ꢀSC-70ꢀPackage
I
LTC3427
500mA ISW, 1.2MHZ, Synchronous Step-Up Dꢀ/Dꢀ
ꢀonverter with Output Disconnect
93% Efficiency VIN: 1.8V to 4.5V, VOUT(MAX) = 5V,
2mm × 2mm DFN Package
LTC3400/LTC3400B
LTC3527/LTC3527-1
600mAꢀISW,ꢀ1.2MHz,ꢀSynchronousꢀStep-Upꢀꢀ
DC/DCꢀConverters
92%ꢀEfficiencyꢀVIN:ꢀ1Vꢀtoꢀ5V,ꢀVOUT(MAX)ꢀ=ꢀ5V,ꢀIQꢀ=ꢀ19µA/300µA,ꢀꢀ
I
SDꢀ<ꢀ1µA,ꢀThinSOT™ꢀPackage
Dualꢀ600mA/400mAꢀI ,ꢀ1.2MHz/2.2MHzꢀSynchronousꢀ 94%ꢀEfficiencyꢀVIN:ꢀ0.7Vꢀtoꢀ5V,ꢀVOUT(MAX)ꢀ=ꢀ5.25V,ꢀIQꢀ=ꢀ12µA,ꢀꢀ
SW
Step-UpꢀDC/DCꢀConverters
ISDꢀ<ꢀ1µA,ꢀ3mm × 3mm QFN-16 Package
3526lfc
LT 0910 REV C • PRINTED IN USA
Linear Technology Corporation
1630 Mcꢀarthy Blvd., Milpitas, ꢀA 95035-7417
ꢀꢅ
●
●
LINEAR TECHNOLOGY CORPORATION 2007
(408)432-1900 FAX: (408) 434-0507 www.linear.com
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