LTC3526EDC-2#TRMPBF [Linear]
LTC3526-2 - 500mA 2MHz Synchronous Step-Up DC/DC Converter in 2mm x 2mm DFN; Package: DFN; Pins: 6; Temperature Range: -40°C to 85°C;
| 型号： | LTC3526EDC-2#TRMPBF |
| 厂家： | 
Linear |
| 描述： | LTC3526-2 - 500mA 2MHz Synchronous Step-Up DC/DC Converter in 2mm x 2mm DFN; Package: DFN; Pins: 6; Temperature Range: -40°C to 85°C 开关 光电二极管 |
| 文件： | 总16页 (文件大小：333K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC3526-2/LTC3526B-2
500mA 2MHz Synchronous
Step-Up DC/DC Converters
in 2mm × 2mm DFN
NOT RECOMMENDED FOR NEW DESIGNS
Contact Linear Technology for Potential Replacement
FeAtures
ꢀ Delivers 3.3V at 100mA from a Single Alkaline/
Description
Theꢀ LTC®3526-2/LTC3526B-2ꢀ areꢀ synchronous,ꢀ fixedꢀ
frequencyꢀstep-upꢀDC/DCꢀconvertersꢀwithꢀoutputꢀdiscon-
nect.ꢀSynchronousꢀrectificationꢀenablesꢀhighꢀefficiencyꢀ
inꢀtheꢀlowꢀprofileꢀ2mmꢀ×ꢀ2mmꢀDFNꢀpackage.ꢀBatteryꢀlifeꢀ
inꢀsingleꢀAA/AAAꢀpoweredꢀproductsꢀisꢀextendedꢀfurtherꢀ
withꢀanꢀ850mVꢀstart-upꢀvoltageꢀandꢀoperationꢀdownꢀtoꢀ
500mVꢀonceꢀstarted.
n
NiMH Cell or 3.3V at 200mA from Two Cells
IN
n
ꢀ V Start-Up Voltage: 850mV
n
n
n
n
n
n
n
n
n
ꢀ V Operating Range: 0.5V to 5V
IN
ꢀ 1.6V to 5.25V V
Range
OUT
ꢀ Up to 94% Efficiency
ꢀ Output Disconnect
ꢀ 2MHz Fixed Frequency Operation
Aꢀswitchingꢀfrequencyꢀofꢀ2MHzꢀminimizesꢀsolutionꢀfoot-
printꢀbyꢀallowingꢀtheꢀuseꢀofꢀtiny,ꢀlowꢀprofileꢀinductorsꢀ
andꢀceramicꢀcapacitors.ꢀTheꢀcurrentꢀmodeꢀPWMꢀdesignꢀ
isꢀinternallyꢀcompensated,ꢀreducingꢀexternalꢀpartsꢀcount.ꢀ
TheꢀLTC3526-2ꢀfeaturesꢀBurstꢀModeꢀoperationꢀatꢀlightꢀloadꢀ
conditions,ꢀ whileꢀ theꢀ LTC3526B-2ꢀ featuresꢀ continuousꢀ
switching.ꢀAnti-ringꢀcircuitryꢀeliminatesꢀEMIꢀconcernsꢀbyꢀ
dampingꢀtheꢀinductorꢀinꢀdiscontinuousꢀmode.ꢀAdditionalꢀ
featuresꢀincludeꢀaꢀlowꢀshutdownꢀcurrentꢀofꢀunderꢀ1µAꢀandꢀ
thermalꢀshutdown.
ꢀ V > V
Operation
IN
OUT
ꢀ Integrated Soft-Start
ꢀ CurrentꢀModeꢀControlꢀwithꢀInternalꢀCompensation
®
ꢀ BurstꢀMode ꢀOperationꢀwithꢀ9µAꢀQuiescentꢀCurrentꢀ
(LTC3526-2)
n
n
n
n
n
ꢀ LowꢀNoiseꢀPWMꢀOperationꢀ(LTC3526B-2)
ꢀ InternalꢀSynchronousꢀRectifier
ꢀ LogicꢀControlledꢀShutdownꢀ(I ꢀ<ꢀ1µA)
Q
ꢀ Anti-RingingꢀControl
ꢀ LowꢀProfileꢀ(2mmꢀ×ꢀ2mmꢀ×ꢀ0.75mm)ꢀDFN-6ꢀPackage
Theꢀ LTC3526-2/LTC3526B-2ꢀ areꢀ housedꢀ inꢀ aꢀ 6-pinꢀ
2mmꢀ×ꢀ2mmꢀ×ꢀ0.75mmꢀDFNꢀpackage.
ApplicAtions
Forꢀ newꢀ designs,ꢀ weꢀ recommendꢀ theꢀ LTC3526L-2/ꢀ
LTC3526LB-2.
L,ꢀLT,ꢀLTC,ꢀLTM,ꢀLinearꢀTechnology,ꢀtheꢀLinearꢀlogoꢀandꢀBurstꢀModeꢀareꢀregisteredꢀtrademarksꢀ
andꢀThinSOTꢀisꢀaꢀtrademarkꢀofꢀLinearꢀTechnologyꢀCorporation.ꢀAllꢀotherꢀtrademarksꢀareꢀtheꢀ
propertyꢀofꢀtheirꢀrespectiveꢀowners.ꢀPatentsꢀpending.
n
ꢀ MedicalꢀInstruments
n
ꢀ Flash-BasedꢀMP3ꢀPlayers
n
ꢀ NoiseꢀCancelingꢀHeadphones
n
ꢀ WirelessꢀMice
n
ꢀ BluetoothꢀHeadsets
typicAl ApplicAtion
LTC3526-2 Efficiency and Power Loss vs Load Current
100
90
1000
100
10
2.2µH
V
= 2.4V
IN
EFFICIENCY
80
SW
V
OUT
70
V
IN
3.3V
V
IN
V
OUT
1.6V TO 3.2V
60
50
200mA
1µF
LTC3526-2
SHDN FB
GND
1.78M
1M
POWER LOSS
OFF ON
4.7µF
40
30
20
10
0
1
0.1
0.01
35262b2 TA01a
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA01b
35262b2fc
ꢀ
ꢀ DC............................................................ –0.3Vꢀtoꢀ6V
V
............................................................. –0.3Vꢀtoꢀ6V
V ꢀVoltage
................................................... –0.3Vꢀtoꢀ6V
LTC3526-2/LTC3526B-2
Absolute MAxiMuM rAtings
pin conFigurAtion
(Note 1)
TOP VIEW
IN
SWꢀVoltage
SW
1
2
3
6
5
4
V
OUT
GND
7
FB
ꢀ Pulsedꢀ<100nsꢀ......................................... –0.3Vꢀtoꢀ7V
V
SHDN
IN
SHDN,ꢀFBꢀVoltageꢀ........................................ –0.3Vꢀtoꢀ6V
DC PACKAGE
6-LEAD (2mm s 2mm) PLASTIC DFN
ꢀ=ꢀ125°C,ꢀθ ꢀ=ꢀ102°C/Wꢀ(NOTEꢀ6)
JA
EXPOSEDꢀPADꢀ(PINꢀ7)ꢀISꢀGND,ꢀMUSTꢀBEꢀSOLDEREDꢀTOꢀPCꢀBOARD
OUT
ꢀ
T
OperatingꢀTemperatureꢀRangeꢀ(Noteꢀ2)ꢀ...–40°Cꢀtoꢀ85°C
StorageꢀTemperatureꢀRangeꢀ.................. –65°Cꢀtoꢀ150°C
JMAX
orDer inForMAtion
LEAD FREE FINISH
LTC3526EDC-2#PBF
LTC3526BEDC-2#PBF
TAPE AND REEL
PART MARKING
LCNM
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC3526EDC-2#TRPBF
LTC3526BEDC-2#TRPBF
–40°Cꢀtoꢀ85°C
–40°Cꢀtoꢀ85°C
6-Leadꢀ(2mmꢀ×ꢀ2mm)ꢀPlasticꢀDFN
6-Leadꢀ(2mmꢀ×ꢀ2mm)ꢀPlasticꢀDFN
LCNP
ConsultꢀLTCꢀMarketingꢀforꢀpartsꢀspecifiedꢀwithꢀwiderꢀoperatingꢀtemperatureꢀranges.ꢀ
ConsultꢀLTCꢀMarketingꢀforꢀinformationꢀonꢀnon-standardꢀleadꢀbasedꢀfinishꢀparts.
Forꢀmoreꢀinformationꢀonꢀleadꢀfreeꢀpartꢀmarking,ꢀgoꢀto:ꢀhttp://www.linear.com/leadfree/ꢀꢀ
Forꢀmoreꢀinformationꢀonꢀtapeꢀandꢀreelꢀspecifications,ꢀgoꢀto:ꢀhttp://www.linear.com/tapeandreel/
electricAl chArActeristics
The l denotes the specifications which apply over the specified operating
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
MIN
TYP
MAX
UNITS
MinimumꢀStart-UpꢀInputꢀVoltage
OutputꢀVoltageꢀAdjustꢀRange
I
ꢀ=ꢀ1mA
0.85
1
V
LOAD
l
l
ꢀ
1.7ꢀ
1.6
5.25ꢀ
5.25
Vꢀ
V
0°Cꢀtoꢀ85°C
FeedbackꢀPinꢀVoltage
1.165
1.195
1
1.225
50
V
FeedbackꢀPinꢀInputꢀCurrentꢀ
QuiescentꢀCurrent—Shutdown
QuiescentꢀCurrent—Active
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
QuiescentꢀCurrent—Burst
MeasuredꢀonꢀV ,ꢀFBꢀ>ꢀ1.230Vꢀ(LTC3526-2ꢀOnly)
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
700
60
5
SW
SW
ꢀ=ꢀ5V,ꢀV ꢀ=ꢀ0V
10
OUT
ꢀ=ꢀ3.3V
OUT
OUT
ꢀ=ꢀ3.3V
Ω
l
500
85
mA
ns
%
(Noteꢀ3)
l
l
l
V
V
ꢀ=ꢀ1.15V,ꢀV ꢀ=ꢀ5V
90
FB
FB
OUT
MinimumꢀDutyꢀCycle
ꢀ=ꢀ1.3V
0
%
SwitchingꢀFrequency
1.8
0.9
2
2.4
MHz
V
SHDNꢀPinꢀInputꢀHighꢀVoltage
SHDNꢀPinꢀInputꢀLowꢀVoltage
SHDNꢀPinꢀInputꢀCurrent
0.3
V
V
V
ꢀ=ꢀ1.2Vꢀ
SHDN
ꢀ=ꢀ3.3V
SHDN
0.3ꢀ
1
1ꢀ
2
µAꢀ
µA
35262b2fc
ꢁ
LTC3526-2/LTC3526B-2
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:ꢀTheꢀLTC3526E-2ꢀisꢀguaranteedꢀtoꢀmeetꢀperformanceꢀspecificationsꢀ
fromꢀ0°Cꢀtoꢀ85°C.ꢀSpecificationsꢀoverꢀ–40°Cꢀtoꢀ85°Cꢀoperatingꢀ
temperatureꢀrangeꢀareꢀassuredꢀbyꢀdesign,ꢀcharacterizationꢀandꢀcorrelationꢀ
withꢀstatisticalꢀprocessꢀcontrols.
Note 3:ꢀSpecificationꢀisꢀguaranteedꢀbyꢀdesignꢀandꢀnotꢀ100%ꢀtestedꢀinꢀ
production.
typicAl perForMAnce chArActeristics
Efficiency vs Load Current and VIN
for VOUT = 1.8V (LTC3526-2)
Efficiency vs Load Current and VIN
for VOUT = 3.3V (LTC3526-2)
No-Load Input Current vs VIN
100
90
1000
100
10
100
90
80
70
60
50
40
30
20
10
100
90
1000
100
10
80
80
V
V
V
= 1.2V
= 2.4V
= 3.0V
V
= 5V
IN
IN
IN
OUT
70
70
V
V
V
= 1.0V
= 1.2V
= 1.5V
IN
IN
IN
V
= 3.3V
OUT
60
50
60
50
V
= 2.5V
OUT
40
30
20
10
0
1
40
30
20
10
0
1
V
= 1.8V
OUT
PLOSS AT V = 1.2V
IN
0.1
0.01
0.1
0.01
PLOSS AT V = 2.4V
IN
PLOSS AT V = 1.0V
IN
PLOSS AT V = 3.0V
IN
PLOSS AT V = 1.2V
IN
PLOSS AT V = 1.5V
IN
0.01
0.1
1
10
100
1000
0.5 1.0
2.5 3.0
(V)
4.5
1.5 2.0
3.5 4.0
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
V
LOAD CURRENT (mA)
IN
35262b2 G02
35262b2 G01
35262b2 G04
Efficiency vs Load Current and VIN
for VOUT = 5V (LTC3526-2)
Minimum Load Resistance
During Start-Up vs VIN
Maximum Output Current vs VIN
100
90
1000
100
10
400
1000
100
10
V
= 3.3V
OUT
350
300
250
200
150
100
50
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
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 = 2.2µH
0
2.5 3.0
0.01
0.1
1
10
100
1000
0.5 1.0 1.5 2.0
3.5 4.0 4.5
0.85
0.95
1.05
(V)
1.25
1.15
V
LOAD CURRENT (mA)
V
(V)
IN
IN
35262b2 G03
35262b2 G05
35262b2 G06
35262b2fc
ꢂ
LTC3526-2/LTC3526B-2
typicAl perForMAnce chArActeristics
Burst Mode Threshold Current
Burst Mode Threshold Current
vs VIN
Start-Up Delay Time vs VIN
vs VIN
100
90
80
70
60
50
40
30
20
10
0
30
25
40
35
30
25
V
C
= 1.8V
V
C
= 2.5V
= 10µF
OUT
OUT
OUT
OUT
= 10µF
L = 2.2µH
L = 2.2µH
20
15
LEAVE BURST
LEAVE BURST
ENTER BURST
20
15
10
5
ENTER BURST
10
5
0
0
1
1.25
(V)
1.5
1.25
1.5
1.0
2.0 2.5 3.0
(V)
3.5 4.0 4.5
1
1.75
1.5
V
V
V
(V)
IN
IN
IN
35262b2 G08a
35262b2 G07
35262b2 G08b
Burst Mode Threshold Current
vs VIN
Burst Mode Threshold Current
vs VIN
Oscillator Frequency Change
vs VOUT
60
2
50
45
40
35
30
25
20
15
10
5
V
C
= 5V
V
C
= 3.3V
= 10µF
NORMALIZED TO 3.3V
OUT
OUT
OUT
OUT
= 10µF
1
0
50 L = 2.2µH
L = 2.2µH
40
LEAVE BURST
–1
–2
–3
–4
–5
LEAVE BURST
30
20
10
0
ENTER BURST
ENTER BURST
2.0 2.5
–6
0
3.0
(V)
4.0
4.5
2.0
2.5
3.5 4.0 4.5 5.0
1.0 1.5
3.5
1.5
3.0
1.0
1.5
2.0
(V)
2.5
3.0
V
V
V (V)
OUT
IN
IN
35262b2 G08d
35262b2 G09
35262b2 G08c
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
1.5
2.5 3.0 3.5
4.0 4.5 5.0
–50 –30 –10 10
30
50
70
90
2.0
V
TEMPERATURE (°C)
TEMPERATURE (°C)
OUT
35262b2 G12
35262b2 G10
35262b2 G11
35262b2fc
ꢃ
LTC3526-2/LTC3526B-2
typicAl perForMAnce chArActeristics
Burst Mode Quiescent Current
vs VOUT
VFB vs Temperature
Start-Up Voltage vs Temperature
10.0
9.5
9.0
8.5
8.0
7.5
7.0
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.50
0.25
LOAD = 1mA
NORMALIZED TO 25°C
0
–0.25
–0.50
–0.75
–1.00
40 60
TEMPERATURE (°C)
3.5
(V)
5.0
–60 –40 –20
0
20
80 100
1.5 2.0 2.5 3.0
4.0 4.5
–50 –30 –10 10
30 –50 70
90
TEMPERATURE (°C)
V
OUT
35262b2 G13
35262b2 G15
35262b2 G14
Fixed Frequency Switching
Waveform and VOUT Ripple
Burst Mode Waveforms
VOUT and IIN During Soft-Start
V
OUT
1V/DIV
SW PIN
2V/DIV
SW PIN
2V/DIV
INPUT
CURRENT
0.2A/DIV
SHDN PIN
1V/DIV
V
OUT
10mV/DIV
V
OUT
AC-COUPLED
50mV/DIV
AC-COUPLED
35262b2 G18
V
C
= 3.3V
= 10µF
200µs/DIV
OUT
OUT
35262b2 G16
35262b2 G17
200ns/DIV
20µs/DIV
= 3.3V AT 5mA
= 10µF
V
V
C
= 1.2V
OUT
OUT
V
V
C
= 1.2V
OUT
OUT
IN
IN
= 3.3V AT 50mA
= 4.7µF
Load Step Response (from Burst
Mode Operation)
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
35262b2 G19
35262b2 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
35262b2fc
ꢄ
LTC3526-2/LTC3526B-2
typicAl perForMAnce chArActeristics
Load Step Response
(Fixed Frequency)
Load Step Response (from Burst
Mode Operation)
V
OUT
V
OUT
100mV/DIV
100mV/DIV
AC-COUPLED
AC-COUPLED
LOAD
CURRENT
50mA/DIV
LOAD
CURRENT
50mA/DIV
35262b2 G21
35262b2 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
Connectꢀresistorꢀdividerꢀtapꢀtoꢀthisꢀpin.ꢀTheꢀtopꢀofꢀtheꢀdividerꢀ
connectsꢀtoꢀtheꢀoutputꢀcapacitor,ꢀtheꢀbottomꢀofꢀtheꢀdividerꢀ
connectsꢀtoꢀGND.ꢀReferringꢀtoꢀtheꢀBlockꢀDiagram,ꢀtheꢀoutputꢀ
voltageꢀcanꢀbeꢀadjustedꢀfromꢀ1.6Vꢀtoꢀ5.25Vꢀby:ꢀ
V .ꢀKeepꢀPCBꢀtraceꢀlengthsꢀasꢀshortꢀandꢀwideꢀasꢀpossibleꢀ
IN
toꢀreduceꢀEMI.ꢀIfꢀtheꢀinductorꢀcurrentꢀfallsꢀtoꢀzeroꢀorꢀSHDNꢀ
isꢀlow,ꢀanꢀinternalꢀanti-ringingꢀswitchꢀisꢀconnectedꢀfromꢀ
SWꢀtoꢀV ꢀtoꢀminimizeꢀEMI.
IN
R2
R1
VOUT =1.195V • 1+
GND (Pin 2):ꢀSignalꢀandꢀPowerꢀGround.ꢀProvideꢀaꢀshortꢀ
directꢀPCBꢀpathꢀbetweenꢀGNDꢀandꢀtheꢀ(–)ꢀsideꢀofꢀtheꢀinputꢀ
andꢀoutputꢀcapacitors.
ꢀ
V
(Pin6):ꢀOutputꢀvoltageꢀsenseꢀandꢀdrainꢀofꢀtheꢀinternalꢀ
OUT
synchronousꢀrectifier.ꢀPCBꢀtraceꢀfromꢀV ꢀtoꢀtheꢀoutputꢀ
OUT
V (Pin 3):ꢀInputꢀSupplyꢀPin.ꢀConnectꢀaꢀminimumꢀofꢀ1µFꢀ
IN
filterꢀcapacitorꢀ(4.7µFꢀminimum)ꢀshouldꢀbeꢀasꢀshortꢀandꢀ
wideꢀasꢀpossible.
ceramicꢀ decouplingꢀ capacitorꢀ fromꢀ thisꢀ pinꢀ toꢀ groundꢀ
usingꢀshortꢀdirectꢀPCBꢀtraces.
GND (Exposed Pad Pin 7):ꢀTheꢀExposedꢀPadꢀmustꢀbeꢀsol-
deredꢀtoꢀtheꢀPCBꢀgroundꢀplane.ꢀItꢀservesꢀasꢀanꢀadditionalꢀ
groundꢀconnectionꢀandꢀasꢀaꢀmeansꢀofꢀconductingꢀheatꢀ
awayꢀfromꢀtheꢀpackage.
SHDN (Pin 4):ꢀLogicꢀControlledꢀShutdownꢀInput.ꢀThereꢀ
isꢀanꢀinternalꢀ4MΩꢀpull-downꢀonꢀthisꢀpin.
ꢀ •ꢀSHDNꢀ=ꢀHigh:ꢀNormalꢀoperation
ꢀ •ꢀSHDNꢀ=ꢀLow:ꢀShutdown,ꢀquiescentꢀcurrentꢀ<ꢀ1µA
FB (Pin 5):ꢀ Feedbackꢀ Inputꢀ toꢀ theꢀ g ꢀ Errorꢀ Amplifier.ꢀ
m
35262b2fc
ꢅ
LTC3526-2/LTC3526B-2
block DiAgrAM
L1
2.2µH
V
IN
0.85V
TO 5V
C
IN
2.2µF
3
1
V
IN
SW
V
OUT
V
SEL
WELL
SWITCH
V
BEST
V
B
V
OUT
V
OUT
FB
1.6V
6
5
TO 5.25V
ANTI-RING
GATE DRIVERS
AND
R2
R1
ANTI-CROSS
CONDUCTION
SHDN
C
OUT
SHUTDOWN
1.195V
4
SHUTDOWN
+
–
4.7µF
I
ZERO
COMP
4M
SLOPE
COMP
I
PK
COMP
V
REF
–
+
I
PK
UVLO
ERROR AMP
SLEEP COMP
I
ZERO
START-UP
V
+
–
REF
LOGIC
MODE
CLK
TSD
CONTROL
2MHz
OSC
CLAMP
WAKE
THERMAL
SHUTDOWN
C
SS
EXPOSED
PAD
GND
2
7
35262b2 BD
operAtion
(Refer to Block Diagram)
TheꢀLTC3526-2/LTC3526B-2ꢀareꢀ2MHzꢀsynchronousꢀboostꢀ rangeꢀofꢀloadꢀcurrents.ꢀAutomaticꢀBurstꢀModeꢀoperationꢀ
convertersꢀhousedꢀinꢀaꢀ6-leadꢀ2mmꢀ×ꢀ2mmꢀDFNꢀpackage.ꢀ maintainsꢀ highꢀ efficiencyꢀ atꢀ veryꢀ lightꢀ loads,ꢀ reducingꢀ
Withꢀtheꢀabilityꢀtoꢀstartꢀupꢀandꢀoperateꢀfromꢀinputsꢀlessꢀ theꢀquiescentꢀcurrentꢀtoꢀjustꢀ9µA.ꢀOperationꢀcanꢀbeꢀbestꢀ
thanꢀ1V,ꢀtheseꢀdevicesꢀfeatureꢀfixedꢀfrequency,ꢀcurrentꢀ understoodꢀbyꢀreferringꢀtoꢀtheꢀBlockꢀDiagram.
modeꢀPWMꢀcontrolꢀforꢀexceptionalꢀlineꢀandꢀloadꢀregula-
tion.ꢀTheꢀcurrentꢀmodeꢀarchitectureꢀwithꢀadaptiveꢀslopeꢀ
LOW VOLTAGE START-UP
compensationꢀprovidesꢀexcellentꢀtransientꢀloadꢀresponse,ꢀ
TheꢀLTC3526-2/LTC3526B-2ꢀincludeꢀanꢀindependentꢀstart-
requiringꢀminimalꢀoutputꢀfiltering.ꢀInternalꢀsoft-startꢀandꢀ
upꢀoscillatorꢀdesignedꢀtoꢀstartꢀupꢀatꢀanꢀinputꢀvoltageꢀofꢀ
internalꢀloopꢀcompensationꢀsimplifiesꢀtheꢀdesignꢀprocessꢀ
0.85Vꢀ(typical).ꢀSoft-startꢀandꢀinrushꢀcurrentꢀlimitingꢀareꢀ
whileꢀminimizingꢀtheꢀnumberꢀofꢀexternalꢀcomponents.
providedꢀduringꢀstart-up,ꢀasꢀwellꢀasꢀnormalꢀmode.
WithꢀitsꢀlowꢀR ꢀandꢀlowꢀgateꢀchargeꢀinternalꢀN-chan-
DS(ON)
Whenꢀ eitherꢀ V ꢀ orꢀ V ꢀ exceedsꢀ 1.4Vꢀ typical,ꢀ theꢀ ICꢀ
IN
OUT
nelꢀMOSFETꢀswitchꢀandꢀP-channelꢀMOSFETꢀsynchronousꢀ
rectifier,ꢀtheꢀLTC3526-2ꢀachievesꢀhighꢀefficiencyꢀoverꢀaꢀwideꢀ
entersꢀnormalꢀoperatingꢀmode.ꢀWhenꢀtheꢀoutputꢀvoltageꢀ
35262b2fc
ꢆ
LTC3526-2/LTC3526B-2
operAtion
(Refer to Block Diagram)
exceedsꢀ theꢀ inputꢀ byꢀ 0.24V,ꢀ theꢀ ICꢀ powersꢀ itselfꢀ fromꢀ
LTC3526-2/LTC3526B-2
4M
LTC3526-2/LTC3526B-2
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
35262b2 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
TheꢀLTC3526-2/LTC3526B-2ꢀcontainꢀinternalꢀcircuitryꢀtoꢀ
provideꢀsoft-startꢀoperation.ꢀTheꢀsoft-startꢀcircuitryꢀslowlyꢀ
rampsꢀtheꢀpeakꢀinductorꢀcurrentꢀfromꢀzeroꢀtoꢀitsꢀpeakꢀvalueꢀ
ofꢀ700mAꢀ(typical)ꢀinꢀapproximatelyꢀ0.5ms,ꢀallowingꢀstart-
upꢀintoꢀheavyꢀloads.ꢀTheꢀsoft-startꢀcircuitryꢀisꢀresetꢀinꢀtheꢀ
eventꢀofꢀaꢀshutdownꢀcommandꢀorꢀaꢀthermalꢀshutdown.
resistiveꢀvoltageꢀdividerꢀfromꢀV ꢀtoꢀgroundꢀprogramsꢀ
OUT
theꢀoutputꢀvoltageꢀviaꢀFBꢀfromꢀ1.6Vꢀtoꢀ5.25V.ꢀ
R2
R1
VOUT =1.195V • 1+
ꢀ
Oscillator
Anꢀ internalꢀ oscillatorꢀ setsꢀ theꢀ switchingꢀ frequencyꢀ toꢀ
2MHz.
Current Sensing
Losslessꢀcurrentꢀsensingꢀconvertsꢀtheꢀpeakꢀcurrentꢀsignalꢀofꢀ
theꢀN-channelꢀMOSFETꢀswitchꢀintoꢀaꢀvoltageꢀthatꢀisꢀsummedꢀ
withꢀtheꢀinternalꢀslopeꢀcompensation.ꢀTheꢀsummedꢀsignalꢀ
isꢀcomparedꢀtoꢀtheꢀerrorꢀamplifierꢀoutputꢀtoꢀprovideꢀaꢀpeakꢀ
currentꢀcontrolꢀcommandꢀforꢀtheꢀPWM.
Shutdown
Shutdownꢀ isꢀ accomplishedꢀ byꢀ pullingꢀ theꢀ SHDNꢀ pinꢀ
belowꢀ0.3VꢀandꢀenabledꢀbyꢀpullingꢀtheꢀSHDNꢀpinꢀaboveꢀ
0.8Vꢀtypical.ꢀAlthoughꢀSHDNꢀcanꢀbeꢀdrivenꢀaboveꢀV ꢀorꢀ
IN
V
ꢀ(upꢀtoꢀtheꢀabsoluteꢀmaximumꢀrating)ꢀwithoutꢀdam-
OUT
Current Limit
age,ꢀtheꢀLTC3526-2/LTC3526B-2ꢀhaveꢀaꢀproprietaryꢀtestꢀ
Theꢀ currentꢀ limitꢀ comparatorꢀ shutsꢀ offꢀ theꢀ N-channelꢀ
MOSFETꢀswitchꢀonceꢀitsꢀthresholdꢀisꢀreached.ꢀTheꢀcur-
rentꢀlimitꢀcomparatorꢀdelayꢀtoꢀoutputꢀisꢀtypicallyꢀ60ns.ꢀ
Peakꢀswitchꢀcurrentꢀisꢀlimitedꢀtoꢀapproximatelyꢀ700mA,ꢀ
independentꢀofꢀinputꢀorꢀoutputꢀvoltage,ꢀunlessꢀV ꢀfallsꢀ
belowꢀ0.7V,ꢀinꢀwhichꢀcaseꢀtheꢀcurrentꢀlimitꢀisꢀcutꢀinꢀhalf.
modeꢀthatꢀmayꢀbeꢀengagedꢀifꢀSHDNꢀisꢀheldꢀinꢀtheꢀrangeꢀ
ofꢀ0.5Vꢀtoꢀ1VꢀhigherꢀthanꢀtheꢀgreaterꢀofꢀV ꢀorꢀV .ꢀIfꢀ
IN
OUT
theꢀtestꢀmodeꢀisꢀengaged,ꢀnormalꢀPWMꢀswitchingꢀactionꢀ
isꢀ interrupted,ꢀ whichꢀ canꢀ causeꢀ undesirableꢀ operationꢀ
inꢀsomeꢀapplications.ꢀTherefore,ꢀinꢀapplicationsꢀwhereꢀ
OUT
SHDNꢀmayꢀbeꢀdrivenꢀaboveꢀV ,ꢀaꢀresistorꢀdividerꢀorꢀotherꢀ
IN
meansꢀmustꢀbeꢀemployedꢀtoꢀkeepꢀtheꢀSHDNꢀvoltageꢀbelowꢀ
Zero Current Comparator
(V ꢀ+ꢀ0.4V)ꢀtoꢀpreventꢀtheꢀpossibilityꢀofꢀtheꢀtestꢀmodeꢀ
IN
Theꢀzeroꢀcurrentꢀcomparatorꢀmonitorsꢀtheꢀinductorꢀcur-
rentꢀtoꢀtheꢀoutputꢀandꢀshutsꢀoffꢀtheꢀsynchronousꢀrectifierꢀ
beingꢀengaged.ꢀPleaseꢀreferꢀtoꢀFigureꢀ1ꢀforꢀtwoꢀpossibleꢀ
implementations.
35262b2fc
ꢇ
LTC3526-2/LTC3526B-2
operAtion
(Refer to Block Diagram)
whenꢀthisꢀcurrentꢀreducesꢀtoꢀapproximatelyꢀ30mA.ꢀThisꢀ Burst Mode OPERATION
preventsꢀtheꢀinductorꢀcurrentꢀfromꢀreversingꢀinꢀpolarity,ꢀ
TheꢀLTC3526-2ꢀwillꢀautomaticallyꢀenterꢀBurstꢀModeꢀopera-
improvingꢀefficiencyꢀatꢀlightꢀloads.
tionꢀatꢀlightꢀloadꢀandꢀreturnꢀtoꢀfixedꢀfrequencyꢀPWMꢀmodeꢀ
whenꢀtheꢀloadꢀincreases.ꢀReferꢀtoꢀtheꢀTypicalꢀPerformanceꢀ
CharacteristicsꢀtoꢀseeꢀtheꢀoutputꢀloadꢀBurstꢀModeꢀthresh-
Synchronous Rectifier
Toꢀ controlꢀ inrushꢀ currentꢀ andꢀ toꢀ preventꢀ theꢀ inductorꢀ
currentꢀfromꢀrunningꢀawayꢀwhenꢀV ꢀisꢀcloseꢀtoꢀV ,ꢀtheꢀ
oldꢀcurrentꢀvsꢀV .ꢀTheꢀloadꢀcurrentꢀatꢀwhichꢀBurstꢀModeꢀ
IN
operationꢀ isꢀ enteredꢀ canꢀ beꢀ changedꢀ byꢀ adjustingꢀ theꢀ
inductorꢀvalue.ꢀRaisingꢀtheꢀinductorꢀvalueꢀwillꢀlowerꢀtheꢀ
loadꢀcurrentꢀatꢀwhichꢀBurstꢀModeꢀoperationꢀisꢀentered.
OUT
IN
P-channelꢀMOSFETꢀsynchronousꢀrectifierꢀisꢀonlyꢀenabledꢀ
whenꢀV ꢀ>ꢀ(V ꢀ+ꢀ0.24V).
OUT
IN
InꢀBurstꢀModeꢀoperation,ꢀtheꢀLTC3526-2ꢀstillꢀswitchesꢀatꢀ
aꢀfixedꢀfrequencyꢀofꢀ2MHz,ꢀusingꢀtheꢀsameꢀerrorꢀamplifierꢀ
andꢀloopꢀcompensationꢀforꢀpeakꢀcurrentꢀmodeꢀcontrol.ꢀ
Thisꢀcontrolꢀmethodꢀeliminatesꢀanyꢀoutputꢀtransientꢀwhenꢀ
switchingꢀbetweenꢀmodes.ꢀInꢀBurstꢀModeꢀoperation,ꢀen-
ergyꢀisꢀdeliveredꢀtoꢀtheꢀoutputꢀuntilꢀitꢀreachesꢀtheꢀnominalꢀ
regulationꢀvalue,ꢀthenꢀtheꢀLTC3526-2ꢀtransitionsꢀtoꢀsleepꢀ
modeꢀwhereꢀtheꢀoutputsꢀareꢀoffꢀandꢀtheꢀLTC3526-2ꢀcon-
Anti-Ringing Control
Theꢀanti-ringingꢀcontrolꢀconnectsꢀaꢀresistorꢀacrossꢀtheꢀ
inductorꢀtoꢀpreventꢀhighꢀfrequencyꢀringingꢀonꢀtheꢀSWꢀpinꢀ
duringꢀdiscontinuousꢀcurrentꢀmodeꢀoperation.ꢀAlthoughꢀ
theꢀringingꢀofꢀtheꢀresonantꢀcircuitꢀformedꢀbyꢀLꢀandꢀC
(capacitanceꢀonꢀSWꢀpin)ꢀisꢀlowꢀenergy,ꢀitꢀcanꢀcauseꢀEMIꢀ
radiation.
ꢀ
SW
sumesꢀonlyꢀ9µAꢀofꢀquiescentꢀcurrentꢀfromꢀV .ꢀWhenꢀtheꢀ
OUT
Output Disconnect
outputꢀvoltageꢀdroopsꢀslightly,ꢀswitchingꢀresumes.ꢀThisꢀ
TheꢀLTC3526-2/LTC3526B-2ꢀareꢀdesignedꢀtoꢀallowꢀtrueꢀ maximizesꢀefficiencyꢀatꢀveryꢀlightꢀloadsꢀbyꢀminimizingꢀ
outputꢀdisconnectꢀbyꢀeliminatingꢀbodyꢀdiodeꢀconductionꢀ switchingꢀandꢀquiescentꢀlosses.ꢀBurstꢀModeꢀoutputꢀvoltageꢀ
ofꢀtheꢀinternalꢀP-channelꢀMOSFETꢀrectifier.ꢀThisꢀallowsꢀforꢀ ripple,ꢀwhichꢀisꢀtypicallyꢀ1%ꢀpeak-to-peak,ꢀcanꢀbeꢀreducedꢀ
V
ꢀtoꢀgoꢀtoꢀzeroꢀvoltsꢀduringꢀshutdown,ꢀdrawingꢀnoꢀcur-
byꢀusingꢀmoreꢀoutputꢀcapacitanceꢀ(10µFꢀorꢀgreater),ꢀorꢀ
OUT
rentꢀfromꢀtheꢀinputꢀsource.ꢀItꢀalsoꢀallowsꢀforꢀinrushꢀcurrentꢀ withꢀaꢀsmallꢀcapacitorꢀ(10pFꢀtoꢀ50pF)ꢀconnectedꢀbetweenꢀ
limitingꢀatꢀturn-on,ꢀminimizingꢀsurgeꢀcurrentsꢀseenꢀbyꢀtheꢀ
inputꢀsupply.ꢀNoteꢀthatꢀtoꢀobtainꢀtheꢀadvantagesꢀofꢀoutputꢀ
disconnect,ꢀthereꢀmustꢀnotꢀbeꢀanꢀexternalꢀSchottkyꢀdiodeꢀ
V ꢀandꢀFB.ꢀ
OUT
Asꢀtheꢀloadꢀcurrentꢀincreases,ꢀtheꢀLTC3526-2ꢀwillꢀautomati-
callyꢀleaveꢀBurstꢀModeꢀoperation.ꢀNoteꢀthatꢀlargerꢀoutputꢀ
capacitorꢀvaluesꢀmayꢀcauseꢀthisꢀtransitionꢀtoꢀoccurꢀatꢀlighterꢀ
loads.ꢀOnceꢀtheꢀLTC3526-2ꢀhasꢀleftꢀBurstꢀModeꢀoperationꢀ
andꢀreturnedꢀtoꢀnormalꢀoperation,ꢀitꢀwillꢀremainꢀthereꢀuntilꢀ
theꢀoutputꢀloadꢀisꢀreducedꢀbelowꢀtheꢀburstꢀthreshold.
connectedꢀbetweenꢀtheꢀSWꢀpinꢀandꢀV .ꢀTheꢀoutputꢀdis-
OUT
connectꢀfeatureꢀalsoꢀallowsꢀV ꢀtoꢀbeꢀpulledꢀhigh,ꢀwithoutꢀ
OUT
anyꢀreverseꢀcurrentꢀintoꢀaꢀbatteryꢀconnectedꢀtoꢀV .
IN
Thermal Shutdown
BurstꢀModeꢀoperationꢀisꢀinhibitedꢀduringꢀstart-upꢀandꢀsoft-
Ifꢀtheꢀdieꢀtemperatureꢀexceedsꢀ160°C,ꢀtheꢀLTC3526-2/
LTC3526B-2ꢀwillꢀgoꢀintoꢀthermalꢀshutdown.ꢀAllꢀswitchesꢀ
startꢀandꢀuntilꢀV ꢀisꢀatꢀleastꢀ0.24VꢀgreaterꢀthanꢀV .
OUT
IN
willꢀbeꢀoffꢀandꢀtheꢀsoft-startꢀcapacitorꢀwillꢀbeꢀdischarged.ꢀ TheꢀLTC3526B-2ꢀfeaturesꢀcontinuousꢀPWMꢀoperationꢀatꢀ
Theꢀdeviceꢀwillꢀbeꢀenabledꢀagainꢀwhenꢀtheꢀdieꢀtemperatureꢀ 2MHz.ꢀAtꢀveryꢀlightꢀloads,ꢀtheꢀLTC3526B-2ꢀwillꢀexhibitꢀ
dropsꢀbyꢀaboutꢀ15°C.
pulse-skipꢀoperation.
35262b2fc
ꢈ
LTC3526-2/LTC3526B-2
ApplicAtions inForMAtion
V > V
OPERATION
COMPONENT SELECTION
Inductor Selection
IN
OUT
TheꢀLTC3526-2/LTC3526B-2ꢀwillꢀmaintainꢀvoltageꢀregula-
tionꢀevenꢀwhenꢀtheꢀinputꢀvoltageꢀisꢀaboveꢀtheꢀdesiredꢀoutputꢀ
voltage.ꢀNoteꢀthatꢀtheꢀefficiencyꢀisꢀmuchꢀlowerꢀinꢀthisꢀmode,ꢀ
andꢀtheꢀmaximumꢀoutputꢀcurrentꢀcapabilityꢀwillꢀbeꢀless.ꢀ
ReferꢀtoꢀtheꢀTypicalꢀPerformanceꢀCharacteristics.
Theꢀ LTC3526-2/LTC3526B-2ꢀ canꢀ utilizeꢀ smallꢀ surfaceꢀ
mountꢀchipꢀinductorsꢀdueꢀtoꢀtheirꢀfastꢀ2MHzꢀswitchingꢀ
frequency.ꢀInductorꢀvaluesꢀbetweenꢀ1.5µHꢀandꢀ3.3µHꢀareꢀ
suitableꢀforꢀmostꢀapplications.ꢀLargerꢀvaluesꢀofꢀinductanceꢀ
willꢀallowꢀslightlyꢀgreaterꢀoutputꢀcurrentꢀcapabilityꢀ(andꢀ
lowerꢀtheꢀBurstꢀModeꢀthreshold)ꢀbyꢀreducingꢀtheꢀinductorꢀ
rippleꢀcurrent.ꢀIncreasingꢀtheꢀinductanceꢀaboveꢀ10µHꢀwillꢀ
increaseꢀsizeꢀwhileꢀprovidingꢀlittleꢀimprovementꢀinꢀoutputꢀ
currentꢀcapability.
SHORT-CIRCUIT PROTECTION
Theꢀ LTC3526-2/LTC3526B-2ꢀ outputꢀ disconnectꢀ featureꢀ
allowsꢀoutputꢀshortꢀcircuitꢀwhileꢀmaintainingꢀaꢀmaximumꢀ
internallyꢀsetꢀcurrentꢀlimit.ꢀToꢀreduceꢀpowerꢀdissipationꢀ
underꢀshort-circuitꢀconditions,ꢀtheꢀpeakꢀswitchꢀcurrentꢀ
limitꢀisꢀreducedꢀtoꢀ400mAꢀ(typical).
Theꢀminimumꢀinductanceꢀvalueꢀisꢀgivenꢀby:
V
• VOUT(MAX) − V
(
)
IN(MIN)
IN(MIN)
L >
SCHOTTKY DIODE
ꢀ
2•RIPPLE • VOUT(MAX)
Althoughꢀitꢀisꢀnotꢀrequired,ꢀaddingꢀaꢀSchottkyꢀdiodeꢀfromꢀ
where:
SWꢀtoꢀV ꢀwillꢀimproveꢀefficiencyꢀbyꢀaboutꢀ2%.ꢀNoteꢀ
OUT
Rippleꢀ=ꢀAllowableꢀinductorꢀcurrentꢀrippleꢀ(ampsꢀpeak-
peak)
thatꢀthisꢀdefeatsꢀtheꢀoutputꢀdisconnectꢀandꢀshort-circuitꢀ
protectionꢀfeatures.
V
V
ꢀ=ꢀMinimumꢀinputꢀvoltage
IN(MIN)
PCB LAYOUT GUIDELINES
ꢀ=ꢀMaximumꢀoutputꢀvoltage
OUT(MAX)
TheꢀhighꢀspeedꢀoperationꢀofꢀtheꢀLTC3526-2/LTC3526B-2ꢀ
demandsꢀ carefulꢀ attentionꢀ toꢀ boardꢀ layout.ꢀ Aꢀ carelessꢀ
layoutꢀwillꢀresultꢀinꢀreducedꢀperformance.ꢀFigureꢀ2ꢀshowsꢀ
theꢀrecommendedꢀcomponentꢀplacement.ꢀAꢀlargeꢀgroundꢀ
pinꢀcopperꢀareaꢀwillꢀhelpꢀtoꢀlowerꢀtheꢀdieꢀtemperature.ꢀAꢀ
multilayerꢀboardꢀwithꢀaꢀseparateꢀgroundꢀplaneꢀisꢀideal,ꢀbutꢀ
notꢀabsolutelyꢀnecessary.
Theꢀinductorꢀcurrentꢀrippleꢀisꢀtypicallyꢀsetꢀforꢀ20%ꢀtoꢀ
40%ꢀofꢀtheꢀmaximumꢀinductorꢀcurrent.ꢀHighꢀfrequencyꢀ
ferriteꢀcoreꢀinductorꢀmaterialsꢀreduceꢀfrequencyꢀdepen-
dentꢀpowerꢀlossesꢀcomparedꢀtoꢀcheaperꢀpowderedꢀironꢀ
types,ꢀimprovingꢀefficiency.ꢀTheꢀinductorꢀshouldꢀhaveꢀ
lowꢀESRꢀ(seriesꢀresistanceꢀofꢀtheꢀwindings)ꢀtoꢀreduceꢀtheꢀ
I2Rꢀpowerꢀlosses,ꢀandꢀmustꢀbeꢀableꢀtoꢀsupportꢀtheꢀpeakꢀ
LTC3526-2
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
35262b2 F02
Figure 2. Recommended Component Placement for Single Layer Board
35262b2fc
ꢀ0
LTC3526-2/LTC3526B-2
ApplicAtions inForMAtion
inductorꢀcurrentꢀwithoutꢀsaturating.ꢀMoldedꢀchokesꢀandꢀ
someꢀchipꢀinductorsꢀusuallyꢀdoꢀnotꢀhaveꢀenoughꢀcoreꢀ
areaꢀtoꢀsupportꢀtheꢀpeakꢀinductorꢀcurrentsꢀofꢀ700mAꢀ
seenꢀonꢀtheꢀLTC3526-2/LTC3526B-2.ꢀToꢀminimizeꢀradiatedꢀ
noise,ꢀuseꢀaꢀshieldedꢀinductor.ꢀSeeꢀTableꢀ1ꢀforꢀsuggestedꢀ
componentsꢀandꢀsuppliers.
Output and Input Capacitor Selection
LowꢀESRꢀ(equivalentꢀseriesꢀresistance)ꢀcapacitorsꢀshouldꢀ
beꢀusedꢀtoꢀminimizeꢀtheꢀoutputꢀvoltageꢀripple.ꢀMultilayerꢀ
ceramicꢀcapacitorsꢀareꢀanꢀexcellentꢀchoiceꢀasꢀtheyꢀhaveꢀ
extremelyꢀlowꢀESRꢀandꢀareꢀavailableꢀinꢀsmallꢀfootprints.ꢀ
Aꢀ4.7µFꢀtoꢀ10µFꢀoutputꢀcapacitorꢀisꢀsufficientꢀforꢀmostꢀ
applications.ꢀLargerꢀvaluesꢀupꢀtoꢀ22µFꢀmayꢀbeꢀusedꢀtoꢀ
obtainꢀextremelyꢀlowꢀoutputꢀvoltageꢀrippleꢀandꢀimproveꢀ
transientꢀresponse.ꢀX5RꢀandꢀX7Rꢀdielectricꢀmaterialsꢀareꢀ
preferredꢀforꢀtheirꢀabilityꢀtoꢀmaintainꢀcapacitanceꢀoverꢀ
wideꢀvoltageꢀandꢀtemperatureꢀranges.ꢀY5Vꢀtypesꢀshouldꢀ
notꢀbeꢀused.
Table 1. Recommended Inductors
VENDOR
PART/STYLE
Coilcraftꢀ
(847)ꢀ639-6400ꢀ
www.coilcraft.com
LPO4815ꢀ
LPS4012,ꢀLPS4018ꢀ
MSS5131ꢀ
MSS4020ꢀ
MOS6020ꢀ
ME3220ꢀ
DS1605,ꢀDO1608
TheꢀinternalꢀloopꢀcompensationꢀofꢀtheꢀLTC3526-2ꢀisꢀde-
signedꢀtoꢀbeꢀstableꢀwithꢀoutputꢀcapacitorꢀvaluesꢀofꢀ4.7µFꢀorꢀ
greaterꢀ(withoutꢀtheꢀneedꢀforꢀanyꢀexternalꢀseriesꢀresistor).ꢀ
Althoughꢀceramicꢀcapacitorsꢀareꢀrecommended,ꢀlowꢀESRꢀ
tantalumꢀcapacitorsꢀmayꢀbeꢀusedꢀasꢀwell.
Coiltronicsꢀ
www.cooperet.com
SD10,ꢀSD12,ꢀSD14,ꢀSD18,ꢀSD20,ꢀ
SD52,ꢀSD3114,ꢀSD3118
FDKꢀ
(408)ꢀ432-8331ꢀ
www.fdk.com
MIP3226D4R7M,ꢀMIP3226D3R3Mꢀ
MIPF2520D4R7ꢀ
MIPWT3226D3R0
Murataꢀ
LQH43Cꢀ
Aꢀsmallꢀceramicꢀcapacitorꢀinꢀparallelꢀwithꢀaꢀlargerꢀtantalumꢀ
capacitorꢀmayꢀbeꢀusedꢀinꢀdemandingꢀapplicationsꢀthatꢀhaveꢀ
largeꢀloadꢀtransients.ꢀAnotherꢀmethodꢀofꢀimprovingꢀtheꢀ
transientꢀresponseꢀisꢀtoꢀaddꢀaꢀsmallꢀfeed-forwardꢀcapacitorꢀ
(714)ꢀ852-2001ꢀ
www.murata.com
LQH32Cꢀ(-53ꢀseries)ꢀ
301015
Sumidaꢀ
(847)ꢀ956-0666ꢀ
www.sumida.com
CDRH5D18ꢀ
CDRH2D14ꢀ
CDRH3D16ꢀ
CDRH3D11ꢀ
CR43ꢀ
CMD4D06-4R7MCꢀ
CMD4D06-3R3MC
acrossꢀtheꢀtopꢀresistorꢀofꢀtheꢀfeedbackꢀdividerꢀ(fromꢀV
toꢀFB).ꢀAꢀtypicalꢀvalueꢀofꢀ22pFꢀwillꢀgenerallyꢀsuffice.
ꢀ
OUT
LowꢀESRꢀinputꢀcapacitorsꢀreduceꢀinputꢀswitchingꢀnoiseꢀ
andꢀreduceꢀtheꢀpeakꢀcurrentꢀdrawnꢀfromꢀtheꢀbattery.ꢀItꢀ
followsꢀthatꢀceramicꢀcapacitorsꢀareꢀalsoꢀaꢀgoodꢀchoiceꢀ
forꢀinputꢀdecouplingꢀandꢀshouldꢀbeꢀlocatedꢀasꢀcloseꢀasꢀ
possibleꢀtoꢀtheꢀdevice.ꢀAꢀ2.2µFꢀinputꢀcapacitorꢀisꢀsufficientꢀ
forꢀ mostꢀ applications,ꢀ althoughꢀ largerꢀ valuesꢀ mayꢀ beꢀ
usedꢀwithoutꢀlimitations.ꢀTableꢀ2ꢀshowsꢀaꢀlistꢀofꢀseveralꢀ
ceramicꢀcapacitorꢀmanufacturers.ꢀConsultꢀtheꢀmanufactur-
ersꢀdirectlyꢀforꢀdetailedꢀinformationꢀonꢀtheirꢀselectionꢀofꢀ
ceramicꢀcapacitors.
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
35262b2fc
ꢀꢀ
LTC3526-2/LTC3526B-2
typicAl ApplicAtions
1-Cell to 1.8V Converter with <1mm Maximum Height for Low-Noise Applications
100
90
V
= 1.8V
OUT
OUT
OUT
2.2µH*
80
70
SW
V
OUT
V
IN
1.8V
V
IN
V
OUT
60
50
1V TO 1.6V
150mA
1µF
LTC3526B-2
SHDN FB
GND
511k
1M
40
30
20
10
0
OFF ON
4.7µF**
35262b2 T02a
V
V
V
= 1.5V
= 1.2V
= 0.9V
IN
IN
IN
*FDK MIPF2520D2R2
**MURATA GRM219R60J475KE19D
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA02b
1-Cell to 3.3V
100
90
V
= 3.3V
2.7µH*
SW
80
70
V
OUT
V
IN
3.3V
V
V
OUT
IN
60
50
1V TO 1.6V
75mA
1.78M
22pF
1µF
LTC3526-2
SHDN FB
GND
40
30
20
10
0
OFF ON
10µF
1M
35262b2 T04a
V
V
V
= 1.5V
= 1.2V
= 0.9V
IN
IN
IN
*TAIYO-YUDEN NP03SB2R7M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA04b
2-Cell to 3.3V
100
V
= 3.3V
2.7µH*
SW
90
80
70
V
OUT
V
IN
2V TO 3.2V
3.3V
V
V
OUT
IN
LTC3526-2
SHDN FB
GND
60
50
200mA
1µF
1.78M
1M
OFF ON
4.7µF
40
30
20
10
0
35262b2 T05a
V
IN
V
IN
V
IN
= 3.0V
= 2.4V
= 1.8V
*TAIYO-YUDEN NP03SB2R7M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA05b
35262b2fc
ꢀꢁ
LTC3526-2/LTC3526B-2
typicAl ApplicAtions
2-Cell to 5V
100
V
= 5V
OUT
90
80
70
3.3µH*
SW
V
OUT
V
60
50
IN
5V
V
IN
V
OUT
2V TO 3.2V
150mA
22pF
1µF
3.24M
1.02M
LTC3526-2
SHDN FB
GND
40
30
20
10
0
OFF ON
10µF
V
V
V
= 3.0V
= 2.4V
= 1.8V
35262b2 TA06a
IN
IN
IN
*TAIYO-YUDEN NP03SB3R3M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA06b
Li-Ion to 5V
100
90
V
= 5V
OUT
3.3µH*
SW
80
70
V
OUT
V
IN
5V
V
IN
V
OUT
2.7V TO 4.3V
60
50
200mA
3.24M
22pF
1µF
LTC3526-2
SHDN FB
GND
OFF ON
10µF
40
30
20
10
0
1.02M
35262b2 TA08a
V
V
V
= 4.2V
= 3.6V
= 3.0V
IN
IN
IN
*TAIYO-YUDEN NP03SB3R3M
0.01
0.1
1
10
100
1000
LOAD CURRENT (mA)
35262b2 TA08b
35262b2fc
ꢀꢂ
LTC3526-2/LTC3526B-2
pAckAge Description
DC Package
6-Lead Plastic DFN (2mm × 2mm)
(ReferenceꢀLTCꢀDWGꢀ#ꢀ05-08-1703ꢀRevꢀB)
0.70 p0.05
2.55 p0.05
1.15 p0.05
0.61 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
35262b2fc
ꢀꢃ
LTC3526-2/LTC3526B-2
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
35262b2fc
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
LTC3526-2/LTC3526B-2
typicAl ApplicAtion
3.3V Converter with Output OR’d with 5V USB Input
MBR120ESFT
5V USB
2.2µH
V
OUT
LDO
3.3V/5V
USB
SW
V
BATT
V
IN
V
OUT
1.8V TO 3.2V
1.78M
1M
1µF
LTC3526-2
SHDN FB
GND
DC/DC
OFF ON
4.7µF
35262b2fA07a
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
LTC3526L/LTC3526LBꢀ
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
35262b2fc
LT 0910 REV C • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
ꢀꢅ
l
l
LINEAR TECHNOLOGY CORPORATION 2006
(408)432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
LTC3526EDC-2#TRPBF
LTC3526-2 - 500mA 2MHz Synchronous Step-Up DC/DC Converter in 2mm x 2mm DFN; Package: DFN; Pins: 6; Temperature Range: -40°C to 85°C
Linear
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