LT1308BCF#TR [Linear]
IC 4.5 A SWITCHING REGULATOR, 750 kHz SWITCHING FREQ-MAX, PDSO14, 4.40 MM, PLASTIC, TSSOP-14, Switching Regulator or Controller;型号: | LT1308BCF#TR |
厂家: | Linear |
描述: | IC 4.5 A SWITCHING REGULATOR, 750 kHz SWITCHING FREQ-MAX, PDSO14, 4.40 MM, PLASTIC, TSSOP-14, Switching Regulator or Controller 开关 光电二极管 |
文件: | 总20页 (文件大小:373K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
LT1308A/LT1308B
High Current, Micropower
Single Cell, 600kHz
DC/DC Converters
DESCRIPTION
The LT®1308A/LT1308B are micropower, fixed frequency
step-up DC/DC converters that operate over a 1V to 10V
input voltage range. They are improved versions of the
LT1308 and are recommended for use in new designs.
The LT1308A features automatic shifting to power sav-
ing Burst Mode operation at light loads and consumes
just 140μA at no load. The LT1308B features continuous
switching at light loads and operates at a quiescent cur-
rent of 2.5mA. Both devices consume less than 1μA in
shutdown.
FEATURES
n
5V at 1A from a Single Li-Ion Cell
n
5V at 800mA in SEPIC Mode from Four NiCd Cells
n
Fixed Frequency Operation: 600kHz
n
Boost Converter Outputs up to 34V
n
Starts into Heavy Loads
n
Automatic Burst Mode™ Operation at
Light Load (LT1308A)
Continuous Switching at Light Loads (LT1308B)
n
n
Low V
Switch: 300mV at 2A
CESAT
n
n
n
Pin-for-Pin Upgrade Compatible with LT1308
Lower Quiescent Current in Shutdown: 1μA (Max)
Improved Accuracy Low-Battery Detector
Reference: 200mV 2%
Low-battery detector accuracy is significantly tighter than
the LT1308. The 200mV reference is specified at 2%
at room and 3% over temperature. The shutdown pin
enables the device when it is tied to a 1V or higher source
n
Available in 8-Lead SO and 14-Lead TSSOP Packages
and does not need to be tied to V as on the LT1308. An
IN
internal V clamp results in improved transient response
C
APPLICATIONS
and the switch voltage rating has been increased to 36V,
n
GSM/CDMA Phones
Digital Cameras
LCD Bias Supplies
Answer-Back Pagers
GPS Receivers
Battery Backup Supplies
Handheld Computers
enabling higher output voltage applications.
n
The LT1308A/LT1308B are available in the 8-lead SO and
the 14-lead TSSOP packages.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
n
n
n
n
n
TYPICAL APPLICATION
Converter Efficiency
L1
95
D1
4.7μH
V
IN
= 3.6V
V
IN
= 4.2V
= 2.5V
5V
1A
90
85
80
75
70
65
60
55
50
V
SW
IN
+
C1
47μF
R1*
LBO
LBI
V
IN
309k
LT1308B
V
IN
= 1.5V
+
Li-Ion
CELL
C2
220μF
SHUTDOWN
SHDN
FB
GND
V
C
R2
100k
47k
100pF
C1: AVX TAJC476M010
C2: AVX TPSD227M006
D1: IR 10BQ015
L1: MURATA LQH6C4R7
*R1: 887k FOR V = 12V
OUT
1
10
100
1000
1308A/B F01a
LOAD CURRENT (mA)
Figure 1. LT1308B Single Li-Ion Cell to 5V/1A DC/DC Converter
1308A/B F01b
1308abfb
1
LT1308A/LT1308B
(Note 1)
ABSOLUTE MAXIMUM RATINGS
V , SHDN, LBO Voltage........................................... 10V
Operating Temperature Range
IN
SW Voltage .............................................. –0.4V to 36V
Commercial............................................. 0°C to 70°C
Extended Commerial (Note 2) ............ –40°C to 85°C
Industrial ........................................... –40°C to 85°C
Storage Temperature Range.................. –65°C to 150°C
Lead Temperature (Soldering, 10 sec) ................. 300°C
FB Voltage......................................................... V + 1V
IN
V Voltage ................................................................. 2V
C
LBI Voltage ................................................. –0.1V to 1V
Current into FB Pin............................................... 1mA
PIN CONFIGURATION
TOP VIEW
LBO
LBI
V
1
2
3
4
5
6
7
14
13
12
11
10
9
C
FB
SHDN
GND
TOP VIEW
V
IN
V
1
2
3
4
8
7
6
5
LBO
LBI
C
V
IN
FB
SHDN
GND
SW
SW
SW
GND
V
IN
GND
SW
GND
8
S8 PACKAGE
8-LEAD PLASTIC SO
F PACKAGE
14-LEAD PLASTIC TSSOP
(NOTE 6)
T
= 125°C, θ = 190°C/W
JA
JMAX
T
JMAX
= 125°C, θ = 80°C/W
JA
OBSOLETE, FOR INFORMATION PURPOSES ONLY
Contact Linear Technology for Potential Replacement
ORDER INFORMATION
LEAD FREE FINISH
LT1308ACS8#PBF
LT1308AIS8#PBF
LT1308BCS8#PBF
LT1308BIS8#PBF
LT1308ACF#PBF
LT1308BCF#PBF
LEAD BASED FINISH
LT1308ACS8
TAPE AND REEL
LT1308ACS8#TRPBF
LT1308AIS8#TRPBF
LT1308BCS8#TRPBF
LT1308BIS8#TRPBF
LT1308ACF#TRPBF
LT1308BCF#TRPBF
TAPE AND REEL
LT1308ACS8#TR
LT1308AIS8#TR
PART MARKING
1308A
PACKAGE DESCRIPTION
8-Lead Plastic SO
TEMPERATURE RANGE
0°C to 70°C
1308AI
8-Lead Plastic SO
–40°C to 85°C
0°C to 70°C
1308B
8-Lead Plastic SO
1308BI
8-Lead Plastic SO
–40°C to 85°C
0°C to 70°C
LT1308ACF
LT1308BCF
PART MARKING
1308A
14-Lead Plastic TSSOP
14-Lead Plastic TSSOP
PACKAGE DESCRIPTION
8-Lead Plastic SO
0°C to 70°C
TEMPERATURE RANGE
0°C to 70°C
LT1308AIS8
1308AI
8-Lead Plastic SO
–40°C to 85°C
0°C to 70°C
LT1308BCS8
LT1308BCS8#TR
LT1308BIS8#TR
1308B
8-Lead Plastic SO
LT1308BIS8
1308BI
8-Lead Plastic SO
–40°C to 85°C
0°C to 70°C
LT1308ACF
LT1308ACF#TR
LT1308ACF
LT1308BCF
14-Lead Plastic TSSOP
14-Lead Plastic TSSOP
LT1308BCF
LT1308BCF#TR
0°C to 70°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
1308abfb
2
LT1308A/LT1308B
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature
range, otherwise specifications are at TA = 25°C. Commercial Grade 0°C to 70°C. VIN = 1.1V, VSHDN = VIN, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Q
Quiescent Current
Not Switching, LT1308A
Switching, LT1308B
SHDN
140
2.5
0.01
240
4
1
μA
mA
μA
V
= 0V (LT1308A/LT1308B)
l
l
l
V
Feedback Voltage
1.20
1.22
27
1.24
80
V
FB
I
B
FB Pin Bias Current
Reference Line Regulation
(Note 3)
nA
1.1V ≤ V ≤ 2V
0.03
0.01
0.4
0.2
%/V
%/V
IN
2V ≤ V ≤ 10V
IN
Minimum Input Voltage
Error Amp Transconductance
Error Amp Voltage Gain
Switching Frequency
0.92
60
1
V
μmhos
V/V
g
∆I = 5μA
m
A
100
600
90
V
l
l
f
V
IN
= 1.2V
500
82
2
700
4.5
kHz
OSC
Maximum Duty Cycle
Switch Current Limit
%
Duty Cycle = 30% (Note 4)
3
A
Switch V
I
SW
I
SW
= 2A (25°C, 0°C), V = 1.5V
290
330
350
400
mV
mV
CESAT
IN
= 2A (70°C), V = 1.5V
IN
Burst Mode Operation Switch Current Limit
(LT1308A)
V
IN
= 2.5V, Circuit of Figure 1
400
mA
l
l
l
Shutdown Pin Current
V
SHDN
V
SHDN
V
SHDN
= 1.1V
= 6V
= 0V
2
5
35
0.1
μA
μA
μA
20
0.01
LBI Threshold Voltage
196
194
200
200
204
206
mV
mV
l
l
l
LBO Output Low
I
= 50μA
0.1
0.01
33
0.25
0.1
V
μA
SINK
LBO Leakage Current
V
V
= 250mV, V
= 5V
LBO
LBI
LBI
LBI Input Bias Current (Note 5)
Low-Battery Detector Gain
Switch Leakage Current
= 150mV
100
nA
3000
0.01
V/V
μA
l
V
= 5V
10
SW
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
Industrial Grade –40°C to 85°C. VIN = 1.2V, VSHDN = VIN, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
l
l
l
I
Q
Quiescent Current
Not Switching, LT1308A
Switching, LT1308B
SHDN
140
2.5
0.01
240
4
1
μA
mA
μA
V
= 0V (LT1308A/LT1308B)
l
l
V
Feedback Voltage
1.19
1.22
27
1.25
80
V
FB
I
FB Pin Bias Current
Reference Line Regulation
(Note 3)
nA
B
l
l
1.1V ≤ V ≤ 2V
0.05
0.01
0.4
0.2
%/V
%/V
IN
2V ≤ V ≤ 10V
IN
Minimum Input Voltage
Error Amp Transconductance
Error Amp Voltage Gain
0.92
60
1
V
μmhos
V/V
g
∆I = 5μA
m
A
100
V
1308abfb
3
LT1308A/LT1308B
The l denotes the specifications which apply over the full operating temperature
ELECTRICAL CHARACTERISTICS
range, otherwise specifications are at TA = 25°C. Industrial Grade –40°C to 85°C. VIN = 1.2V, VSHDN = VIN, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN
500
82
TYP
600
90
MAX
UNITS
kHz
%
l
l
f
Switching Frequency
Maximum Duty Cycle
Switch Current Limit
750
OSC
Duty Cycle = 30% (Note 4)
2
3
4.5
A
Switch V
I
I
= 2A (25°C, –40°C), V = 1.5V
290
330
350
400
mV
mV
CESAT
SW
SW
IN
= 2A (85°C), V = 1.5V
IN
Burst Mode Operation Switch Current Limit
(LT1308A)
V
= 2.5V, Circuit of Figure 1
400
mA
IN
l
l
Shutdown Pin Current
V
SHDN
V
SHDN
V
SHDN
= 1.1V
= 6V
= 0V
2
5
35
0.1
μA
μA
μA
20
0.01
LBI Threshold Voltage
196
193
200
200
204
207
mV
mV
l
l
l
LBO Output Low
I
= 50μA
0.1
0.01
33
0.25
0.1
V
μA
SINK
LBO Leakage Current
V
V
= 250mV, V
= 5V
LBO
LBI
LBI Input Bias Current (Note 5)
Low-Battery Detector Gain
Switch Leakage Current
= 150mV
100
nA
LBI
3000
0.01
V/V
μA
l
V
= 5V
10
SW
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LT1308ACS8, LT1308ACF, LT1308BCS8 and LT1308BCF are
designed, characterized and expected to meet the industrial temperature
limits, but are not tested at –40°C and 85°C. I grade devices are
guaranteed over the –40°C to 85°C operating temperature range.
Note 4: Switch current limit guaranteed by design and/or correlation to
static tests. Duty cycle affects current limit due to ramp generator (see
Block Diagram).
Note 5: Bias current flows out of LBI pin.
Note 6: Connect the four GND pins (Pins 4–7) together at the device.
Similarly, connect the three SW pins (Pins 8–10) together and the two V
pins (Pins 11, 12) together at the device.
IN
Note 3: Bias current flows into FB pin.
TYPICAL PERFORMANCE CHARACTERISTICS
LT1308B
3.3V Output Efficiency
LT1308A
3.3V Output Efficiency
LT1308A
5V Output Efficiency
95
90
85
80
75
70
65
60
55
50
95
90
85
80
75
70
65
60
55
50
95
90
85
80
75
70
65
60
55
50
V
= 4.2V
= 2.5V
IN
V
= 2.5V
IN
V = 3.6V
IN
V
= 1.8V
V
= 2.5V
IN
IN
V
IN
= 1.8V
V
IN
= 1.2V
V
IN
= 1.5V
V
= 1.2V
V
IN
IN
1
10
100
1000
1
10
100
1000
1
10
100
1000
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LOAD CURRENT (mA)
1308A/B G02
1308A/B G01
1308A/B G03
1308abfb
4
LT1308A/LT1308B
TYPICAL PERFORMANCE CHARACTERISTICS
LT1308B
Switch Current Limit vs
Duty Cycle
Switch Saturation Voltage
12V Output Efficiency
vs Current
4.0
3.5
3.0
2.5
2.0
500
90
85
80
75
70
65
60
55
50
V
IN
= 5V
400
V
IN
= 3.3V
85°C
300
25°C
200
–40°C
100
0
0.5
1.0
1.5
0
2.0
0
20
40
60
80
100
1
10
100
1000
LOAD CURRENT (mA)
SWITCH CURRENT (A)
DUTY CYCLE (%)
1308A/B G04
1308 G06
1308 • G05
FB, LBI Bias Current vs
Temperature
Low Battery Detector Reference
vs Temperature
SHDN Pin Bias Current vs Voltage
50
40
30
20
10
0
80
70
60
50
40
30
20
10
0
203
202
201
200
199
198
197
196
195
–40°C
LBI
25°C
85°C
FB
75
0
2
4
6
8
10
–50
–25
0
25
50
100
75
–50
–25
0
25
50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
SHDN PIN VOLTAGE (V)
1308 G07
1308 • G08
1308 • G09
Oscillator Frequency vs
Temperature
LT1308A Quiescent Current vs
Temperature
Feedback Pin Voltage vs
Temperature
180
170
160
150
140
130
120
110
100
1.25
1.24
1.23
1.22
1.21
1.20
1.19
1.18
800
750
700
650
600
550
500
450
400
75
–50
–25
0
25
50
100
75
75
–50
–25
0
25
50
100
–50
–2.5
0
25
50
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1308 • G11
1308 • G12
1308 • G10
1308abfb
5
LT1308A/LT1308B
PIN FUNCTIONS (SO/TSSOP)
V (Pin 1/Pin 1): Compensation Pin for Error Amplifier.
SW (Pin 5/Pins 8, 9, 10): Switch Pins. Connect induc-
tor/diode here. Minimize trace area at these pins to keep
EMI down. For the TSSOP package, connect all SW pins
together at the package.
C
ConnectaseriesRCfromthispintoground.Typicalvalues
are 47kΩ and 100pF. Minimize trace area at V .
C
FB (Pin 2/Pin 2): Feedback Pin. Reference voltage is
1.22V. Connect resistive divider tap here. Minimize trace
V (Pin 6/Pins 11, 12): Supply Pins. Must have local
IN
area at FB. Set V
according to:
bypass capacitor right at the pins, connected directly to
OUT
ground. For the TSSOP package, connect both V pins
IN
V
= 1.22V(1 + R1/R2).
OUT
together at the package.
SHDN (Pin 3/Pin 3): Shutdown. Ground this pin to turn
off switcher. To enable, tie to 1V or more. SHDN does
LBI (Pin 7/Pin 13): Low-Battery Detector Input. 200mV
reference. Voltage on LBI must stay between –100mV
and 1V. Low-battery detector does not function with
SHDN pin grounded. Float LBI pin if not used.
not need to be at V to enable the device.
IN
GND (Pin 4/Pins 4, 5, 6, 7): Ground. Connect directly
to local ground plane. Ground plane should enclose all
components associated with the LT1308. PCB copper
connected to these pins also functions as a heat sink. For
the TSSOP package, connect all pins to ground copper
to get the best heat transfer. This keeps chip heating to
a minimum.
LBO (Pin 8/Pin 14): Low-Battery Detector Output. Open
collector,cansink50μA.A220kΩpull-upisrecommend-
ed. LBO is high impedance when SHDN is grounded.
1308abfb
6
LT1308A/LT1308B
BLOCK DIAGRAMS
V
IN
V
IN
Q4
2V
BE
6
V
IN
R5
40k
R6
40k
SHDN
SHUTDOWN
3
+
V
C
g
1
m
V
OUT
LBI
7
–
+
–
+
–
R1
LBO
8
ERROR
AMPLIFIER
(EXTERNAL)
*
FB
2
ENABLE
200mV
Q1
Q2
FB
×10
BIAS
A4
A1
COMPARATOR
R2
R3
30k
(EXTERNAL)
SW
5
–
+
DRIVER
R4
140k
FF
RAMP
GENERATOR
Q3
R
Q
+
Σ
S
A2
+
+
A = 3
–
0.03Ω
600kHz
OSCILLATOR
4
*HYSTERESIS IN LT1308A ONLY
1308 BD2a
GND
Figure 2a. LT1308A/LT1308B Block Diagram (SO-8 Package)
V
IN
Q4
2V
BE
V
V
11
12
IN
V
IN
R5
40k
R6
40k
SHDN
IN
SHUTDOWN
3
+
V
C
g
1
m
V
OUT
LBI
13
–
+
–
+
–
R1
LBO
14
ERROR
AMPLIFIER
(EXTERNAL)
*
FB
2
ENABLE
200mV
Q1
Q2
FB
×10
BIAS
A4
A1
COMPARATOR
R2
SW SW SW
8 10
R3
30k
(EXTERNAL)
9
–
+
DRIVER
R4
140k
FF
RAMP
GENERATOR
Q3
R
Q
+
Σ
S
A2
+
+
A = 3
–
0.03ꢀ
5
600kHz
OSCILLATOR
4
6
7
*HYSTERESIS IN LT1308A ONLY
1308 BD2b
GND GND GND GND
Figure 2b. LT1308A/LT1308B Block Diagram (TSSOP Package)
1308abfb
7
LT1308A/LT1308B
APPLICATIONS INFORMATION
OPERATION
Low-battery detector A4’s open-collector output (LBO)
pulls low when the LBI pin voltage drops below 200mV.
There is no hysteresis in A4, allowing it to be used as an
amplifierinsomeapplications.Theentiredeviceisdisabled
whentheSHDNpinisbroughtlow.Toenabletheconverter,
The LT1308A combines a current mode, fixed frequency
PWM architecture with Burst Mode micropower opera-
tion to maintain high efficiency at light loads. Operation
can be best understood by referring to the block diagram
in Figure 2. Q1 and Q2 form a bandgap reference core
whose loop is closed around the output of the converter.
SHDN must be at 1V or greater. It need not be tied to V
IN
as on the LT1308.
When V is 1V, the feedback voltage of 1.22V, along with
The LT1308B differs from the LT1308A in that there is no
hysteresis in comparator A1. Also, the bias point on A1 is
set lower than on the LT1308B so that switching can occur
at inductor current less than 100mA. Because A1 has no
hysteresis, there is no Burst Mode operation at light loads
and the device continues switching at constant frequency.
Thisresultsintheabsenceoflowfrequencyoutputvoltage
ripple at the expense of efficiency.
IN
an 80mV drop across R5 and R6, forward biases Q1 and
Q2’sbasecollectorjunctionsto300mV. Becausethisisnot
enough to saturate either transistor, FB can be at a higher
voltage than V . When there is no load, FB rises slightly
IN
above 1.22V, causing V (the error amplifier’s output) to
C
decrease. When V reaches the bias voltage on hyster-
C
etic comparator A1, A1’s output goes low, turning off
all circuitry except the input stage, error amplifier and
low-battery detector. Total current consumption in this
state is 140μA. As output loading causes the FB voltage to
decrease,A1’soutputgoeshigh,enablingtherestoftheIC.
Switch current is limited to approximately 400mA initially
after A1’s output goes high. If the load is light, the output
voltage(andFBvoltage)willincreaseuntilA1’soutputgoes
low, turning off the rest of the LT1308A. Low frequency
ripple voltage appears at the output. The ripple frequency
is dependent on load current and output capacitance.
This Burst Mode operation keeps the output regulated
and reduces average current into the IC, resulting in high
efficiency even at load currents of 1mA or less.
The difference between the two devices is clearly illus-
trated in Figure 3. The top two traces in Figure 3 shows an
LT1308A/LT1308Bcircuit,usingthecomponentsindicated
in Figure 1, set to a 5V output. Input voltage is 3V. Load
current is stepped from 50mA to 800mA for both circuits.
Low frequency Burst Mode operation voltage ripple is
observed on Trace A, while none is observed on Trace B.
Atlightloads,theLT1308Bwillbegintoskipalternatecycles.
The load point at which this occurs can be decreased by
increasing the inductor value. However, output ripple will
continue to be significantly less than the LT1308A output
ripple. Further, theLT1308Bcanbeforcedintomicropower
mode, where I falls from 3mA to 200μA by sinking 40μA
Q
If the output load increases sufficiently, A1’s output
remains high, resulting in continuous operation. When the
LT1308A is running continuously, peak switch current is
or more out of the V pin. This stops switching by causing
C
A1’s output to go low.
controlled by V to regulate the output voltage. The switch
C
is turned on at the beginning of each switch cycle. When
the summation of a signal representing switch current
and a ramp generator (introduced to avoid subharmonic
oscillations at duty factors greater than 50%) exceeds the
TRACE A: LT1308A
V
, 100mV/DIV
OUT
AC COUPLED
TRACE B: LT1308B
V
, 100mV/DIV
OUT
AC COUPLED
V signal, comparator A2 changes state, resetting the flip-
C
800mA
I
LOAD
flop and turning off the switch. Output voltage increases
as switch current is increased. The output, attenuated
by a resistor divider, appears at the FB pin, closing the
overall loop. Frequency compensation is provided by an
50mA
1308 F03
200μs/DIV
(CIRCUIT OF FIGURE 1)
V
IN
= 3V
external series RC network connected between the V pin
Figure 3. LT1308A Exhibits Burst Mode Operation Output
Voltage Ripple at 50mA Load, LT1308B Does Not
C
and ground.
1308abfb
8
LT1308A/LT1308B
APPLICATIONS INFORMATION
WaveformsforaLT1308B5Vto12Vboostconverterusing
a 10μF ceramic output capacitor are pictured in Figures 4
and 5. In Figure 4, the converter is operating in continuous
mode, delivering a load current of approximately 500mA.
Thetoptraceistheoutput.Thevoltageincreasesasinduc-
tor current is dumped into the output capacitor during the
switchofftime,andthevoltagedecreaseswhentheswitch
is on. Ripple voltage is in this case due to capacitance,
as the ceramic capacitor has little ESR. The middle trace
is the switch voltage. This voltage alternates between a
LAYOUT HINTS
The LT1308A/LT1308B switch current at high speed, man-
dating careful attention to layout for proper performance.
You will not get advertised performance with careless
layout. Figure 6 shows recommended component place-
mentforanSO-8packageboost(step-up)converter.Follow
this closely in your PC layout. Note the direct path of the
switching loops. Input capacitor C1 must be placed close
(<5mm) to the IC package. As little as 10mm of wire or PC
trace from C to V will cause problems such as inability
IN
IN
V
and V
plus the diode drop. The lower trace is
CESAT
OUT
to regulate or oscillation.
the switch current. At the beginning of the switch cycle,
the current is 1.2A. At the end of the switch on time, the
currenthasincreasedto2A,atwhichpointtheswitchturns
offandtheinductorcurrentflowsintotheoutputcapacitor
through the diode. Figure 5 depicts converter waveforms
at a light load. Here the converter operates in discontinu-
ous mode. The inductor current reaches zero during the
switch off time, resulting in some ringing at the switch
node. The ring frequency is set by switch capacitance,
diode capacitance and inductance. This ringing has little
energy, and its sinusoidal shape suggests it is free from
harmonics. Minimizing the copper area at the switch node
will prevent this from causing interference problems.
The negative terminal of output capacitor C2 should tie
close to the ground pin(s) of the LT1308A/LT1308B. Doing
this reduces dI/dt in the ground copper which keeps high
frequency spikes to a minimum. The DC/DC converter
groundshouldtietothePCboardgroundplaneatoneplace
only, to avoid introducing dI/dt in the ground plane.
LBI
LBO
GROUND PLANE
C1
+
V
IN
R1
1
2
3
4
8
V
OUT
7
6
5
LT1308A
LT1308B
L1
100mV/DIV
R2
SHUTDOWN
V
SW
10V/DIV
MULTIPLE
VIAs
+
I
D1
SW
500mA/DIV
C2
GND
1308 F04
V
OUT
500ns/DIV
Figure 4. 5V to 12V Boost Converter Waveforms in
Continuous Mode. 10μF Ceramic Capacitor Used at Output
1308 F04
Figure 6. Recommended Component Placement for SO-8
Package Boost Converter. Note Direct High Current Paths
V
OUT
20mV/DIV
Using Wide PC Traces. Minimize Trace Area at Pin 1 (VC) and
Pin 2 (FB). Use Multiple Vias to Tie Pin 4 Copper to Ground
Plane. Use Vias at One Location Only to Avoid Introducing
Switching Currents into the Ground Plane
V
SW
10V/DIV
I
SW
500mA/DIV
Figure 7 shows recommended component placement for
a boost converter using the TSSOP package. Placement
is similar to the SO-8 package layout.
1308abfb
1308 F05
500ns/DIV
Figure 5. Converter Waveforms in Discontinuous Mode
9
LT1308A/LT1308B
APPLICATIONS INFORMATION
A SEPIC (Single-Ended Primary Inductance Converter)
schematic is shown in Figure 8. This converter topology
produces a regulated output over an input voltage range
that spans (i.e., can be higher or lower than) the output.
RecommendedcomponentplacementforanSO-8package
SEPIC is shown in Figure 9.
LBI
LBO
GROUND PLANE
C1
+
V
IN
R1
1
2
3
4
5
6
7
14
C2
13
12
11
10
9
4.7μF
CERAMIC
L1
R2
L1A
CTX10-2
D1
SHUTDOWN
V
IN
3V TO
10V
LT1308A
LT1308B
V
IN
SW
+
L1B
C1
47μF
MULTIPLE
VIAs
R1
309k
LT1308B
V
OUT
8
5V
SHUTDOWN
SHDN
FB
GND
500mA
V
C
R2
100k
+
+
D1
C3
220μF
6.3V
47k
680pF
C2
GND
V
OUT
C1: AVX TAJC476M016
C2: TAIYO YUDEN EMK325BJ475(X5R)
C3: AVX TPSD227M006
D1: IR 10BQ015
L1: COILTRONICS CTX10-2
1308A/B F08
1308 F07
Figure 7. Recommended Component
Placement for TSSOP Boost Converter.
Placement is Similar to Figure 4
Figure 8. SEPIC (Single-Ended Primary
Inductance Converter) Converts 3V to 10V
Input to a 5V/500mA Regulated Output
LBI
LBO
GROUND PLANE
C1
+
V
IN
R1
1
2
8
7
6
5
LT1308A
LT1308B
R2
SHUTDOWN
3
4
L1A
C2
L1B
MULTIPLE
VIAs
C3
+
GND
D1
V
OUT
1308 F09
Figure 9. Recommended Component Placement for SEPIC
1308abfb
10
LT1308A/LT1308B
APPLICATIONS INFORMATION
SHDN PIN
A cross plot of the low-battery detector is shown in
Figure 12. The LBI pin is swept with an input which var-
ies from 195mV to 205mV, and LBO (with a 100k pull-up
resistor) is displayed.
The LT1308A/LT1308B SHDN pin is improved over the
LT1308. The pin does not require tying to V to enable
IN
the device, but needs only a logic level signal. The voltage
on the SHDN pin can vary from 1V to 10V independent
of V . Further, floating this pin has the same effect as
IN
grounding, which is to shut the device down, reducing
current drain to 1μA or less.
V
LBO
1V/DIV
LOW-BATTERY DETECTOR
The low-battery detector on the LT1308A/LT1308B fea-
tures improved accuracy and drive capability compared
to the LT1308. The 200mV reference has an accuracy of
2% and the open-collector output can sink 50μA. The
LT1308A/LT1308B low-battery detector is a simple PNP
input gain stage with an open-collector NPN output. The
negativeinputofthegainstageistiedinternallytoa200mV
reference.ThepositiveinputistheLBIpin.Arrangementas
alow-batterydetectorisstraightforward. Figure10details
hookup. R1 and R2 need only be low enough in value so
that the bias current of the LBI pin doesn’t cause large
errors. For R2, 100k is adequate. The 200mV reference
can also be accessed as shown in Figure 11.
195
200
(mV)
205
1308 F12
V
LBI
Figure 12. Low-Battery Detector
Input/Output Characteristic
START-UP
TheLT1308A/LT1308Bcanstartupintoheavyloads,unlike
manyCMOSDC/DCconvertersthatderiveoperatingvoltage
from the output (a technique known as “bootstrapping”).
Figure 13 details start-up waveforms of Figure 1’s circuit
with a 20Ω load and V of 1.5V. Inductor current rises to
IN
3.5A as the output capacitor is charged. After the output
reaches 5V, inductor current is about 1A. In Figure 14, the
load is 5Ω and input voltage is 3V. Output voltage reaches
5V in 500μs after the device is enabled. Figure 15 shows
start-up behavior of Figure 5’s SEPIC circuit, driven from a
9V input with a 10Ω load. The output reaches 5V in about
1ms after the device is enabled.
5V
R1
V
IN
LT1308A
LT1308B
100k
LBI
+
–
LBO
TO PROCESSOR
R2
100k
200mV
V
– 200mV
2μA
LB
R1 =
INTERNAL
V
BAT
REFERENCE
GND
V
OUT
1308 F10
2V/DIV
I
L1
1A/DIV
Figure 10. Setting Low-Battery Detector Trip Point
V
SHDN
5V/DIV
200k
V
IN
2N3906
REF
LBO
LBI
1308 F13
1ms/DIV
V
BAT
LT1308A
LT1308B
V
200mV
+
Figure 13. 5V Boost Converter of Figure 1.
Start-Up from 1.5V Input into 20Ω Load
GND
10k
10μF
1308 F11
Figure 11. Accessing 200mV Reference
1308abfb
11
LT1308A/LT1308B
APPLICATIONS INFORMATION
whenoperatingfromabatterycomposedofalkalinecells.
Theinrushcurrentmaycausesufficiencyinternalvoltage
drop to trigger a low-battery indicator. A programmable
soft-start can be implemented with 4 discrete compo-
nents. A 5V to 12V boost converter using the LT1308B
V
OUT
1V/DIV
I
L1
2A/DIV
V
SHDN
is detailed in Figure 16. C4 differentiates V , causing
OUT
5V/DIV
a current to flow into R3 as V
increases. When this
OUT
1308 F14
current exceeds 0.7V/33k, or 21μA, current flows into
500μs/DIV
the base of Q1. Q1’s collector then pulls current out the
Figure 14. 5V Boost Converter of Figure 1.
Start-Up from 3V Input into 5Ω Load
V pin, creating a feedback loop where the slope of V
C
OUT
is limited as follows:
V
OUT
ΔVOUT
Δt
0.7V
33k •C4
2V/DIV
=
I
SW
2A/DIV
With C4 = 33nF, V /t is limited to 640mV/ms. Start-up
OUT
waveformsforFigure16’scircuitarepicturedinFigure17.
Withoutthesoft-startcircuitimplemented,theinrushcur-
rentreaches3A.Thecircuitreachesfinaloutputvoltagein
approximately 250μs. Adding the soft-start components
reduces inductor current to less than 1A, as detailed in
Figure 18, while the time required to reach final output
voltage increases to about 15ms. C4 can be adjusted to
achieve any output slew rate desired.
V
SHDN
5V/DIV
1308 F15
500μs/DIV
Figure 15. 5V SEPIC Start-Up from 9V Input into 10Ω Load
Soft-Start
In some cases it may be undesirable for the LT1308A/
LT1308B to operate at current limit during start-up, e.g.,
L1
4.7μH
D1
V
OUT
V
IN
12V
5V
500mA
V
IN
SW
+
SHDN
SHUTDOWN
C1
47μF
LT1308B
330pF
11.3k
100k
10k
C2
10μF
FB
GND
V
C
C4
33nF
R4
33k
R
C
Q1
47k
C
C
R3
33k
100pF
SOFT-START
COMPONENTS
C1: AVX TAJ476M010
1308 F16
C2: TAIYO YUDEN TMK432BJ106MM
D1: IR 10BQ015
L1: MURATA LQH6C4R7
Q1: 2N3904
Figure 16. 5V to 12V Boost Converter with Soft-Start Components Q1, C4, R3 and R4
1308abfb
12
LT1308A/LT1308B
APPLICATIONS INFORMATION
that copper loss is minimized. Acceptable inductance
values range between 2μH and 20μH, with 4.7μH best for
most applications. Lower value inductors are physically
smaller than higher value inductors for the same current
capability.
12V
V
OUT
5V/DIV
5V
I
L1
1A/DIV
V
SHDN
10V/DIV
Table 1 lists some inductors we have found to perform
well in LT1308A/LT1308B application circuits. This is not
an exclusive list.
1308 F17
50μs/DIV
Figure 17. Start-Up Waveforms of Figure 16’s Circuit
without Soft-Start Components
Table 1
VENDOR
Murata
PART NO.
LQH6C4R7
CDRH734R7
CTX5-1
VALUE
4.7μH
4.7μH
5μH
PHONE NO.
770-436-1300
847-956-0666
561-241-7876
847-639-6400
12V
V
OUT
Sumida
5V
Coiltronics
Coilcraft
LPO2506IB-472
4.7μH
I
L1
1A/DIV
V
Capacitors
SHDN
10V/DIV
Equivalent Series Resistance (ESR) is the main issue
regarding selection of capacitors, especially the output
capacitors.
1308 F18
5ms/DIV
Figure 18. Start-Up Waveforms of Figure 16’s Circuit
with Soft-Start Components Added
The output capacitors specified for use with the LT1308A/
LT1308B circuits have low ESR and are specifically
designed for power supply applications. Output voltage
ripple of a boost converter is equal to ESR multiplied by
switchcurrent.TheperformanceoftheAVXTPSD227M006
220μF tantalum can be evaluated by referring to Figure 3.
Whentheloadis800mA,thepeakswitchcurrentisapproxi-
COMPONENT SELECTION
Diodes
We have found ON Semiconductor MBRS130 and Inter-
national Rectifier 10BQ015 to perform well. For applica-
tions where V
exceeds 30V, use 40V diodes such as
mately 2A. Output voltage ripple is about 60mV , so the
OUT
P-P
MBRS140 or 10BQ040.
ESR of the output capacitor is 60mV/2A or 0.03Ω. Ripple
can be further reduced by paralleling ceramic units.
Heightlimitedapplicationsmaybenefitfromtheuseofthe
MBRM120. This component is only 1mm tall and offers
performance similar to the MBRS130.
Table 2 lists some capacitors we have found to perform
well in the LT1308A/LT1308B application circuits. This is
not an exclusive list.
Inductors
Table 2
SuitableinductorsforusewiththeLT1308A/LT1308Bmust
fulfill two requirements. First, the inductor must be able
to handle current of 2A steady-state, as well as support
transient and start-up current over 3A without inductance
decreasing by more than 50% to 60%. Second, the DCR
of the inductor should have low DCR, under 0.05Ω so
VENDOR
AVX
SERIES
TPS
PART NO.
VALUE
PHONE NO.
TPSD227M006 220μF, 6V 803-448-9411
TPSD107M010 100μF, 10V 803-448-9411
LMK432BJ226 22μF, 10V 408-573-4150
TMK432BJ106 10μF, 25V 408-573-4150
AVX
TPS
Taiyo Yuden
Taiyo Yuden
X5R
X5R
1308abfb
13
LT1308A/LT1308B
APPLICATIONS INFORMATION
Ceramic Capacitors
Without C , load step response is pictured in Figure 22.
PL
Although the output settles faster than the tantalum case,
thereisappreciableringing,againsuggestingphasemargin
islow.Figure23depictsloadstepresponseusingthe10μF
Multilayer ceramic capacitors have become popular, due
to their small size, low cost, and near-zero ESR. Ceramic
capacitors can be used successfully in LT1308A/LT1308B
designs provided loop stability is considered. A tantalum
capacitor has some ESR and this causes an "ESR zero" in
the regulator loop. This zero is beneficial to loop stability.
Ceramics do not have appreciable ESR, so the zero is lost
when they are used. However, the LT1308A/LT1308B have
ceramic output capacitor and C . Response is clean and
PL
no ringing is evident. Ceramic capacitors have the added
benefit of lowering ripple at the switching frequency due
to their very low ESR. By applying C in tandem with the
PL
series RC at the V pin, loop response can be tailored to
C
optimize response using ceramic output capacitors.
external compensation pin (V ) so component values can
C
be adjusted to achieve stability. A phase lead capacitor can
also be used to tune up load step response to optimum
levels, as detailed in the following paragraphs.
V
OUT
500mV/DIV
I
L1
Figure 19 details a 5V to 12V boost converter using either
a tantalum or ceramic capacitor for C2. The input capaci-
tor has little effect on loop stability, as long as minimum
capacitance requirements are met. The phase lead capaci-
1A/DIV
500mA
50mA
LOAD
CURRENT
1308 F20
200μs/DIV
tor C parallels feedback resistor R1. Figure 20 shows
PL
load step response of a 50mA to 500mA load step using a
47μF tantalum capacitor at the output. Without the phase
lead capacitor, there is some ringing, suggesting the
Figure 20. Load Step Response of LT1308B 5V to 12V
Boost Converter with 47μF Tantalum Output Capacitor
phase margin is low. C is then added, and response to
PL
V
OUT
the same load step is pictured in Figure 21. Some phase
margin is restored, improving the response. Next, C2 is
replaced by a 10μF, X5R dielectric, ceramic capacitor.
500mV/DIV
I
L1
L1
4.7μH
1A/DIV
D1
V
OUT
V
IN
12V
5V
500mA
50mA
500mA
LOAD
CURRENT
1308 F21
200μs/DIV
V
IN
SW
SHDN
Figure 21. Load Step Response with 47μF Tantalum
Output Capacitor and Phase Lead Capacitor CPL
C
R1
100k
PL
LT1308B
R3
10k
330pF
FB
GND
C2
V
C
V
+
OUT
C1
47μF
500mV/DIV
R2
11.3k
47k
100pF
I
L1
1A/DIV
500mA
50mA
LOAD
CURRENT
C1: AVX TAJC476M010
C2: AVX TPSD476M016 (47μF) OR
TAIYO YUDEN TMK432BJ106MM (10μF)
D1: IR 10BQ015
L1: MURATA LQH6C4R7
1308 F19
1308 F22
200μs/DIV
Figure 22. Load Step Response with 10μF X5R
Ceramic Output Capacitor
Figure 19. 5V to 12V Boost Converter
1308abfb
14
LT1308A/LT1308B
APPLICATIONS INFORMATION
V
V
OUT
OUT
V
V
= 4.2V
500mV/DIV
IN
IN
V
V
OUT
= 3.6V
I
L1
1A/DIV
V
= 3V
OUT
IN
I
LOAD
1A
1mA
500mA
50mA
LOAD
CURRENT
1308 F23
1308 F25
200μs/DIV
200μs/DIV
V
TRACES =
OUT
200mV/DIV
Figure 23. Load Step Response with 10μF X5R
Ceramic Output Capacitor and CPL
Figure 25. LT1308A Li-Ion to 5V Boost Converter
Transient Response to 1A Load Step
GSM AND CDMA PHONES
The LT1308A/LT1308B are suitable for converting a single
Li-Ion cell to 5V for powering RF power stages in GSM or
CDMA phones. Improvements in the LT1308A/LT1308B
error amplifiers allow external compensation values to be
reduced, resulting in faster transient response compared
to the LT1308. The circuit of Figure 24 (same as Figure 1,
printed again for convenience) provides a 5V, 1A output
from a Li-Ion cell. Figure 25 details transient response at
V
OUT
V
= 4.2V
IN
IN
V
V
OUT
V
= 3.6V
V
OUT
= 3V
IN
I
LOAD
1A
10mA
1308 F26
100μs/DIV
V
TRACES =
OUT
theLT1308AoperatingataV of4.2V, 3.6Vand3V. Ripple
IN
200mV/DIV
voltage in Burst Mode operation can be seen at 10mA
load. Figure 26 shows transient response of the LT1308B
under the same conditions. Note the lack of Burst Mode
ripple at 10mA load.
Figure 26. LT1308B Li-Ion to 5V Boost
Converter Transient Response to 1A Load Step
L1
4.7μH
D1
5V
1A
V
IN
SW
+
C1
47μF
R1
LT1308B
309k
+
Li-Ion
CELL
C2
220μF
SHUTDOWN
SHDN
FB
GND
V
C
R2
100k
47k
100pF
C1: AVX TAJC476M010
C2: AVX TPSD227M006
D1: IR 10BQ015
L1: MURATA LQH6N4R7
1308A/B F24
Figure 24. Li-Ion to 5V Boost Converter Delivers 1A
1308abfb
15
LT1308A/LT1308B
TYPICAL APPLICATIONS
Triple Output TFTLCD Bias Supply
D2
V
OFF
–9V
C4
10mA
1μF
D3
V
ON
27V
C5
1μF
0.22μF
0.22μF
15mA
D4
C6
1μF
0.22μF
L1
4.7μH
D1
V
IN
5V
AV
DD
6
5
10V
V
SW
IN
500mA
3
1
SHDN
76.8k
10.7k
C2, C3
10μF
×2
C1
LT1308B
4.7μF
2
FB
V
C
GND
4
220k
100pF
C1:TAIYO-YUDEN JMK212BJ475MG
C2, C3:TAIYO-YUDEN LMK325BJ106MN
1308 TA02
C4, C5, C6:TAIYO-YUDEN EMK212BJ105MG
D1: MBRM120
D2,D3,D4: BAT54S
L1: TOKO 817FY-4R7M
TFTLCD Bias Supply Transient Response
AV
DD
500mV/DIV
V
ON
500mV/DIV
V
OFF
500mV/DIV
800mA
I
LOAD
200mA
100μs/DIV
1308abfb
16
LT1308A/LT1308B
TYPICAL APPLICATIONS
40nF EL Panel Driver
T1
1:12
D2
D3
V
BAT
3V TO 6V
4
6
+
3
C1
47μF
1
D1
3.3V
REGULATED
1μF
2M
100k
V
SW
IN
4.3M
Q1
LBO
FB
47k
LT1308A
17k
C2
324k
150k
1μF
200V
LBI
V
SHUTDOWN
SHDN
GND
C
Q2
400V
EL PANEL
≤40nF
100pF
47pF
22nF
49.9k
3.3k
10k
1308 TA03
Q1: MMBT3906
Q2: ZETEX FCX458
T1: MIDCOM 31105
C1: AVX TAJC476M010
C2: VITRAMON VJ225Y105KXCAT
D1: BAT54
D2, D3: BAV21
High Voltage Supply 350V at 1.2mA
SEPIC Converts 3V to 10V Input to a 5V/500mA Regulated Output
10nF
250V
D3
V
OUT
C2
350V
4.7μF
L1A
1.2mA
10nF
250V
CERAMIC
D1
T1
1:12
D2
CTX10-2
LT1308B
V
IN
D1
V
3V TO
10V
IN
2.7V TO 6V
+
3
4
6
C1
47μF
V
SW
IN
10nF
250V
+
L1B
C1
1
47μF
R1
309k
V
OUT
D4
5V
SHUTDOWN
SHDN
FB
GND
500mA
V
C
R2
100k
V
SW
IN
+
C3
220μF
6.3V
47k
680pF
SHUTDOWN
SHDN
LT1308A
10M
C1: AVX TAJC476M016
C2: TAIYO YUDEN EMK325BJ475(X5R)
C3: AVX TPSD227M006
D1: IR 10BQ015
L1: COILTRONICS CTX10-2
FB
V
C
1308A/B TA05
GND
47k
10nF
100pF
34.8k
D1, D2, D3: BAV21 200mA, 250V
D4: MBR0540
1308 TA04
T1: MIDCOM 31105R L = 1.5μH
P
1308abfb
17
LT1308A/LT1308B
PACKAGE DESCRIPTION
S8 Package
8-Lead Plastic Small Outline (Narrow .150 Inch)
(Reference LTC DWG # 05-08-1610)
.189 – .197
(4.801 – 5.004)
NOTE 3
.045 .005
.050 BSC
7
5
8
6
.245
MIN
.160 .005
.150 – .157
(3.810 – 3.988)
NOTE 3
.228 – .244
(5.791 – 6.197)
.030 .005
TYP
1
2
3
4
RECOMMENDED SOLDER PAD LAYOUT
.010 – .020
(0.254 – 0.508)
× 45°
.053 – .069
(1.346 – 1.752)
.004 – .010
(0.101 – 0.254)
.008 – .010
(0.203 – 0.254)
0°– 8° TYP
.016 – .050
(0.406 – 1.270)
.050
(1.270)
BSC
.014 – .019
(0.355 – 0.483)
TYP
NOTE:
INCHES
1. DIMENSIONS IN
(MILLIMETERS)
2. DRAWING NOT TO SCALE
3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)
SO8 0303
F Package
14-Lead Plastic TSSOP (4.4mm)
(Reference LTC DWG # 05-08-1650)
4.90 – 5.10*
(.193 – .201)
14 13 12 11 10
9 8
1.05 0.10
4.50 0.10
6.60 0.10
6.40
(.252)
BSC
0.45 0.05
0.65 BSC
5
7
6
1
2
3
4
RECOMMENDED SOLDER PAD LAYOUT
1.10
(.0433)
MAX
4.30 – 4.50**
(.169 – .177)
0.25
REF
0° – 8°
0.65
(.0256)
BSC
0.09 – 0.20
(.0035 – .0079)
0.50 – 0.75
(.020 – .030)
0.05 – 0.15
(.002 – .006)
F14 TSSOP 0204
0.19 – 0.30
(.0075 – .0118)
TYP
NOTE:
1. CONTROLLING DIMENSION: MILLIMETERS
MILLIMETERS
2. DIMENSIONS ARE IN
(INCHES)
3. DRAWING NOT TO SCALE
*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED .152mm (.006") PER SIDE
**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE
1308abfb
18
LT1308A/LT1308B
REVISION HISTORY (Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
12/10 Obsoleted F Package
2
1308abfb
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LT1308A/LT1308B
TYPICAL APPLICATION
Li-Ion to 12V/300mA Step-Up DC/DC Converter
L1
4.7μH
D1
2.7V TO 4.2V
12V
300mA
V
IN
SW
+
C1
47μF
R1
887k
LT1308B
+
Li-Ion
CELL
C2
100μF
SHUTDOWN
SHDN
FB
GND
V
C
R2
100k
47k
330pF
C1: AVX TAJC476M010
C2: AVX TPSD107M016
D1: IR 10BQ015
L1: MURATA LQH6C4R7
1308A/B TA01
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LT1302
High Output Current Micropower DC/DC Converter
2-Cell Micropower DC/DC Converter
5V/600mA from 2V, 2A Internal Switch, 200μA I
Q
LT1304
5V/200mA, Low-Battery Detector Active in Shutdown
3.3V at 75mA from One Cell, MSOP Package
LT1307/LT1307B
LT1316
Single Cell, Micropower, 600kHz PWM DC/DC Converters
Burst Mode Operation DC/DC with Programmable Current Limit
Micropower, 600kHz PWM DC/DC Converters
Micropower Step-Down DC/DC Converter
1.5V Minimum, Precise Control of Peak Current Limit
LT1317/LT1317B
LTC®1474
LTC1516
LTC1522
LT1610
100μA I , Operate with V as Low as 1.5V
Q IN
94% Efficiency, 10μA I , 9V to 5V at 250mA
Q
2-Cell to 5V Regulated Charge Pump
12μA I , No Inudctors, 5V at 50mA from 3V Input
Q
Micropower, 5V Charge Pump DC/DC Converter
Single-Cell Micropower DC/DC Converter
Regulated 5V 4% Output, 20mA from 3V Input
3V at 30mA from 1V, 1.7MHz Fixed Frequency
–5V at 150mA from 5V Input, Tiny SOT-23 package
5V at 200mA from 4.4V Input, Tiny SOT-23 package
LT1611
Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23
1.4MHz Switching Regulator in 5-Lead SOT-23
Micropower Step-Up DC/DC in 5-Lead SOT-23
Micropower Inverting DC/DC Converter in SOT-23
Doubler Charge Pump with Low Noise LDO
600kHz, 1A Switch PWM DC/DC Converter
1.1MHz, 1A Switch DC/DC Converter
LT1613
LT1615
20μA I , 36V, 350mA Switch
Q
LT1617
V
IN
= 1V to 15V; V
to –34V
OUT
LTC1682
LT1949
Adjustable or Fixed 3.3V, 5V Outputs, 60μV
Output Noise
RMS
1.1A, 0.5Ω, 30V Internal Switch, V as Low as 1.5V
IN
LT1949-1
1.1MHz Version of LT1949
1308abfb
LT 1210 REV B • PRINTED IN USA
20 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
© LINEAR TECHNOLOGY CORPORATION 1999
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号:
LT1308BCS8#PBF
LT1308A and B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C
Linear
LT1308BCS8#TR
LT1308A and B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C
Linear
LT1308BIS8#PBF
LT1308A and B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C
Linear
LT1308BIS8#TRPBF
LT1308A and B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter; Package: SO; Pins: 8; Temperature Range: -40°C to 85°C
Linear
©2020 ICPDF网 联系我们和版权申明