LT1945IMS#TRPBF [Linear]
LT1945 - Dual Micropower DC/DC Converter with Positive and Negative Outputs; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C;
| 型号： | LT1945IMS#TRPBF |
| 厂家： | 
Linear |
| 描述： | LT1945 - Dual Micropower DC/DC Converter with Positive and Negative Outputs; Package: MSOP; Pins: 10; Temperature Range: -40°C to 85°C 开关 光电二极管 |
| 文件： | 总8页 (文件大小：122K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LT1945
Dual Micropower DC/DC
Converter with Positive and
Negative Outputs
FEATURES
DESCRIPTION
The LT®1945 is a dual micropower DC/DC converter in a
10-pin MSOP package. Each converter is designed with
a 350mA current limit and an input voltage range of 1.2V
to 15V, making the LT1945 ideal for a wide variety of ap-
plications. Both converters feature a quiescent current of
only 20μA at no load, which further reduces to 0.5μA in
shutdown.Acurrentlimited,fixedoff-timecontrolscheme
conserves operating current, resulting in high efficiency
over a broad range of load current. The 36V switch allows
high voltage outputs up to 34V to be easily generated
without the use of costly transformers. The LT1945’s
low off-time of 400ns permits the use of tiny, low profile
inductors and capacitors to minimize footprint and cost
in space-conscious portable applications.
n
Generates Well-Regulated Positive and
Negative Outputs
Low Quiescent Current:
n
20μA in Active Mode (per Converter)
<1μA in Shutdown Mode
n
Operates with V as Low as 1.2V
IN
n
Low V
Switch: 250mV at 300mA
CESAT
n
n
n
Uses Small Surface Mount Components
High Output Voltage: Up to 34V
Tiny 10-Pin MSOP Package
APPLICATIONS
n
Small TFT LCD Panels
n
Handheld Computers
n
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Battery Backup
Digital Cameras
n
TYPICAL APPLICATION
Dual Output (+12V, –20V) Converter
Efficiency at VIN = 3.6V
90
C4
L1
0.1μF
D1
10μH
V
IN
85
80
75
70
65
60
55
50
–20V
2.7V
+12V OUTPUT
–20V OUTPUT
10mA
TO 5V
8
10
SW1
100pF
365k
V
IN
2
4
1
5
SHDN1
NFB1
C1
4.7μF
C2
1μF
LT1945
D2
SHDN2
FB2
24.9k
GND PGND PGND SW2
3
7
9
6
115k
1M
0.1
1
10
100
C3
1μF
LOAD CURRENT (mA)
4.7pF
D3
1945 TA01a
L2
10μH
12V
20mA
C1: TAIYO YUDEN JMK212BJ475
1945 TA01
C2, C3: TAIYO YUDEN TMK316BJ105
C4: TAIYO YUDEN EMK107BJ104
D1, D2, D3: ZETEX ZHCS400
L1, L2: MURATA LQH3C100
1945fa
1
LT1945
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
TOP VIEW
V , SHDN1, SHDN2 Voltage.....................................15V
IN
NFB1
SHDN1
GND
SHDN2
FB2
1
2
3
4
5
10 SW1
9
8
7
6
PGND
SW1, SW2 Voltage....................................................36V
NFB1 Voltage ............................................................–3V
FB2 Voltage............................................................... VIN
Current into NFB1 Pin ............................................–1mA
Current into FB2 Pin................................................1mA
Junction Temperature ........................................... 125°C
Operating Temperature Range (Note 2).... –40°C to 85°C
Storage Temperature Range................... –65°C to 150°C
Lead Temperature (Soldering, 10 sec) .................. 300°C
V
IN
PGND
SW2
MS PACKAGE
10-LEAD PLASTIC MSOP
= 125°C, θ = 160°C/W
T
JMAX
JA
ORDER INFORMATION
LEAD FREE FINISH
LT1945EMS#PBF
LT1945IMS#PBF
LEAD BASED FINISH
LT1945EMS
TAPE AND REEL
LT1945EMS#TRPBF
LT1945IMS#TRPBF
TAPE AND REEL
LT1945EMS#TR
LT1945IMS#TR
PART MARKING*
PACKAGE DESCRIPTION
10-Lead Plastic MSOP
10-Lead Plastic MSOP
PACKAGE DESCRIPTION
10-Lead Plastic MSOP
10-Lead Plastic MSOP
TEMPERATURE RANGE
–40°C to 85°C
LTTS
LTTS
–40°C to 125°C
PART MARKING*
TEMPERATURE RANGE
–40°C to 85°C
LTTS
LTTS
LT1945IMS
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Minimum Input Voltage
Quiescent Current, (per Converter)
1.2
V
Not Switching
SHDN
20
30
1
μA
μA
V
= 0V
NFB1 Comparator Trip Point
FB2 Comparator Trip Point
–40°C < T < 85°C
–1.205
–1.195
–1.23
1.23
–1.255
1.255
V
V
J
–40°C < T < 125°C
J
–40°C < T < 85°C
1.205
1.195
1.255
1.255
V
V
J
–40°C < T < 125°C
J
FB Comparator Hysteresis
8
0.05
2
mV
%/V
μA
NFB1, FB2 Voltage Line Regulation
NFB1 Pin Bias Current (Note 3)
FB2 Pin Bias Current (Note 4)
1.2V < V < 12V
0.1
2.9
IN
l
V = –1.23V
NFB1
1.3
–40°C < T < 85°C
30
80
300
nA
nA
J
–40°C < T < 125°C
J
Switch Off Time, Switcher 1 (Note 5)
Switch Off Time, Switcher 2 (Note 5)
400
ns
V
FB2
V
FB2
> 1V
< 0.6V
400
1.5
ns
μs
Switch V
I
SW
= 300mA
250
350
350
400
mV
mA
CESAT
Switch Current Limit
250
1945fa
2
LT1945
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 1.2V, VSHDN = 1.2V unless otherwise noted.
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
SHDN Pin Current
V
SHDN
V
SHDN
= 1.2V
= 5V
2
8
3
12
μA
μA
SHDN Input Voltage High
SHDN Input Voltage Low
Switch Leakage Current
0.9
V
V
0.25
5
Switch Off, V = 5V
0.01
μA
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.
characterization and correlation with statistical process controls. The
LT1945I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 2: The LT1945E is guaranteed to meet performance specifications
from 0°C to 70°C junction temperature. Specifications over the –40°C
to 85°C operating junction temperature range are assured by design,
Note 3: Bias current flows out of the NFB1 pin.
Note 4: Bias current flows into the FB2 pin.
Note 5: See Figure 1 for Switcher 1 and Switcher 2 locations.
TYPICAL PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage
(VCESAT)
FB2 Pin Voltage and
Bias Current
NFB1 Pin Voltage and
Bias Current
0.60
0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
1.25
1.24
1.23
1.22
1.21
1.20
50
40
30
20
10
0
5
4
3
2
1
0
–1.25
–1.24
–1.23
–1.22
–1.21
–1.20
VOLTAGE
VOLTAGE
CURRENT
I
I
= 500mA
= 300mA
SWITCH
SWITCH
CURRENT
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1945 G01
1945 G02
1945 G03
Switch Off Time
Switch Current Limit
Quiescent Current
550
400
25
23
21
19
17
15
V
= 12V
IN
V
= 1.23V
FB
350
300
250
200
150
100
50
NOT SWITCHING
500
450
400
350
300
250
V
= 1.2V
IN
V
= 1.2V
IN
V
= 12V
IN
V
= 12V
IN
V
= 1.2V
50
IN
0
–50
–25
0
25
50
75
100
–50
–25
0
25
50
75
100
–50
–25
0
25
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
1945 G04
1945 G05
1945 G06
1945fa
3
LT1945
PIN FUNCTIONS
NFB1 (Pin 1): Feedback Pin for Switcher 1. Set the output
voltage by selecting values for R1 and R2.
SW2 (Pin 6): Switch Pin for Switcher 2. This is the
collector of the internal NPN power switch. Minimize the
metal trace area connected to the pin to minimize EMI.
SHDN1 (Pin 2): Shutdown Pin for Switcher 1. Tie this
pin to 0.9V or higher to enable device. Tie below 0.25V
to turn it off.
PGND (Pins 7, 9): Power Ground. Tie these pins directly
to the local ground plane. Both pins must be tied.
GND (Pin 3): Ground. Tie this pin directly to the local
ground plane.
V
(Pin 8): Input Supply Pin. Bypass this pin with a
IN
capacitor as close to the device as possible.
SHDN2 (Pin 4): Shutdown Pin for Switcher 2. Tie this
pin to 0.9V or higher to enable device. Tie below 0.25V
to turn it off.
SW1 (Pin 10): Switch Pin for Switcher 1. This is the
collector of the internal NPN power switch. Minimize the
metal trace area connected to the pin to minimize EMI.
FB2 (Pin 5): Feedback Pin for Switcher 2. Set the output
voltage by selecting values for R1B and R2B.
BLOCK DIAGRAM
C3
D2
L1
L2
L3
V
V
V
OUT2
V
IN
IN
OUT1
D1
C2
C1
C4
V
SHDN1
SW1
SW2
SHDN2
IN
8
2
10
6
4
V
IN
R5
80k
R6
80k
R6B
40k
R5B
40k
A1
A1B
+
+
ENABLE
ENABLE
V
OUT2
–
–
R1B
Q1B
(EXTERNAL)
FB2
Q1
400ns
400ns
Q2
X10
Q2B
X10
5
Q3
Q3B
ONE-SHOT
ONE-SHOT
R2B
(EXTERNAL)
DRIVER
DRIVER
R3
60k
R3B
30k
RESET
RESET
+
+
–
R4
280k
R4B
140k
0.12Ω
0.12Ω
V
OUT1
–
42mV
42mV
A2
A2B
R1
(EXTERNAL)
NFB1
SWITCHER 1
SWITCHER 2
1
R2
PGND PGND
GND
3
9
7
(EXTERNAL)
1945 BD
Figure 1. LT1945 Block Diagram
OPERATION
The LT1945 uses a constant off-time control scheme
to provide high efficiencies over a wide range of output
current. Operation can be best understood by referring
to the block diagram in Figure 1. Q1 and Q2 along with
R3 and R4 form a bandgap reference used to regulate
the output voltage. When the voltage at the NFB1 pin is
slightly below –1.23V, comparator A1 disables most of
the internal circuitry. Output current is then provided by
capacitor C2, which slowly discharges until the voltage
at the NFB1 pin goes above the hysteresis point of A1
(typicalhysteresisattheNFB1pinis8mV).A1thenenables
the internal circuitry, turns on power switch Q3, and the
1945fa
4
LT1945
OPERATION
current in inductors L1 and L2 begins ramping up. Once
the switch current reaches 350mA, comparator A2 resets
the one-shot, which turns off Q3 for 400ns. L2 continues
to deliver current to the output while Q3 is off. Q3 turns on
again and the inductor currents ramp back up to 350mA,
then A2 again resets the one-shot. This switching action
continues until the output voltage is charged up (until the
NFB1 pin reaches –1.23V), then A1 turns off the internal
circuitry and the cycle repeats.
The second switching regulator is a step-up converter
(whichgeneratesapositiveoutput)butthebasicoperation
is the same.The LT1945 contains additional circuitry to
provide protection during start-up and under short-circuit
conditions. When the FB2 pin voltage is less than approxi-
mately 600mV, the switch off-time is increased to 1.5μs
and the current limit is reduced to around 250mA (70%
of its normal value). This reduces the average inductor
current and helps minimize the power dissipation in the
power switch and in the external inductor and diode.
APPLICATIONS INFORMATION
Choosing an Inductor
A smaller value can be used (especially for systems with
outputvoltagesgreaterthan12V)togiveasmallerphysical
size. Inductance can be calculated as:
Several recommended inductors that work well with the
LT1945 are listed in Table 1, although there are many other
manufacturersanddevicesthatcanbeused. Consulteach
manufacturer for more detailed information and for their
entire selection of related parts. Many different sizes and
shapesareavailable. Usetheequationsandrecommenda-
tionsinthenextfewsectionstofindthecorrectinductance
value for your design.
VOUT − VIN MIN) + VD
(
L =
tOFF
ILIM
where V = 0.4V (Schottky diode voltage), I = 350mA
D
LIM
and t
= 400ns; for designs with varying V such as
OFF
IN
battery powered applications, use the minimum V value
IN
in the above equation. For most regulators with output
voltages below 7V, a 4.7μH inductor is the best choice,
even though the equation above might specify a smaller
value. This is due to the inductor current overshoot that
occurs when very small inductor values are used (see
Current Limit Overshoot section).
Table 1. Recommended Inductors
PART
VALUE (μH)
MAX DCR (Ω) VENDOR
LQH3C4R7
LQH3C100
LQH3C220
4.7
10
22
0.26
0.30
0.92
Murata
(714) 852-2001
www.murata.com
CD43-4R7
4.7
10
4.7
10
0.11
0.18
0.16
0.20
Sumida
(847) 956-0666
www.sumida.com
CD43-100
CDRH4D18-4R7
CDRH4D18-100
Forhigheroutputvoltages,theformulaabovewillgivelarge
inductance values. For a 2V to 20V converter (typical LCD
Bias application), a 21μH inductor is called for with the
aboveequation,buta10μHinductorcouldbeusedwithout
excessive reduction in maximum output current.
DO1608-472
DO1608-103
DO1608-223
4.7
10
22
0.09
0.16
0.37
Coilcraft
(847) 639-6400
www.coilcraft.com
Inductor Selection—Boost Regulator
Inductor Selection—SEPIC Regulator
Theformulabelowcalculatestheappropriateinductorvalue
to be used for a boost regulator using the LT1945 (or at
least provides a good starting point). This value provides
a good tradeoff in inductor size and system performance.
Pick a standard inductor close to this value. A larger value
canbeusedtoslightlyincreasetheavailableoutputcurrent,
but limit it to around twice the value calculated below, as
too large of an inductance will increase the output voltage
ripple without providing much additional output current.
The formula below calculates the approximate inductor
value to be used for a SEPIC regulator using the LT1945.
As for the boost inductor selection, a larger or smaller
value can be used.
⎛
⎞
VOUT + VD
L = 2
tOFF
⎜
⎟
ILIM
⎝
⎠
1945fa
5
LT1945
APPLICATIONS INFORMATION
Inductor Selection—Inverting Regulator
Current Limit Overshoot
Theformulabelowcalculatestheappropriateinductorvalue
to be used for an inverting regulator using the LT1945 (or
atleastprovidesagoodstartingpoint).Thisvalueprovides
a good tradeoff in inductor size and system performance.
Pickastandardinductorclosetothisvalue(bothinductors
should be the same value). A larger value can be used to
slightly increase the available output current, but limit it to
around twice the value calculated below, as too large of an
inductance will increase the output voltage ripple without
providing much additional output current. A smaller value
can be used (especially for systems with output voltages
greaterthan12V)togiveasmallerphysicalsize.Inductance
can be calculated as:
For the constant off-time control scheme of the LT1945,
thepowerswitchisturnedoffonlyafterthe350mAcurrent
limit is reached. There is a 100ns delay between the time
when the current limit is reached and when the switch
actually turns off. During this delay, the inductor current
exceeds the current limit by a small amount. The peak
inductor current can be calculated by:
V
IN(MAX)− VSAT
⎛
⎞
IPEAK =ILIM
+
100ns
⎜
⎟
L
⎝
⎠
WhereV =0.25V(switchsaturationvoltage).Thecurrent
SAT
overshootwillbemostevidentforregulatorswithhighinput
voltages and smaller inductor values. This overshoot can
be beneficial as it helps increase the amount of available
output current for smaller inductor values. This will be the
peak current seen by the inductor (and the diode) during
normaloperation.Fordesignsusingsmallinductancevalues
(especially at input voltages greater than 5V), the current
limit overshoot can be quite high. Although it is internally
current limited to 350mA, the power switch of the LT1945
can handle larger currents without problem, but the overall
⎛
⎞
VOUT + VD
L = 2
t
⎜
⎟ OFF
ILIM
⎝
⎠
where V = 0.4V (Schottky diode voltage), I = 350mA
D
LIM
and t = 400ns.
OFF
For higher output voltages, the formula above will give
large inductance values. For a 2V to 20V converter (typical
LCD bias application), a 47μH inductor is called for with the
above equation, but a 10μH or 22μH inductor could be used
without excessive reduction in maximum output current.
efficiencywillsuffer.BestresultswillbeobtainedwhenI
is kept below 700mA for the LT1945.
PEAK
Capacitor Selection
Inductor Selection—Inverting Charge Pump Regulator
LowESR(EquivalentSeriesResistance)capacitorsshould
beusedattheoutputtominimizetheoutputripplevoltage.
X5R or X7R multilayer ceramic capacitors are the best
choice, as they have a very low ESR and are available in
verysmallpackages.Y5Vceramicsarenotrecommended.
Their small size makes them a good companion to the
LT1945’s MS10 package. Solid tantalum capacitors (like
theAVXTPS,Sprague593Dfamilies)orOS-CONcapacitors
can be used, but they will occupy more board area than a
ceramicandwillhaveahigherESR.Alwaysuseacapacitor
with a sufficient voltage rating.
For the inverting regulator, the voltage seen by the internal
power switch is equal to the sum of the absolute value of
the input and output voltages, so that generating high output
voltages from a high input voltage source will often exceed
the 36V maximum switch rating. For instance, a 12V to –30V
converter using the inverting topology would generate 42V
on the SW pin, exceeding its maximum rating. For this ap-
plication, an inverting charge pump is the best topology.
The formula below calculates the approximate inductor
value to be used for an inverting charge pump regulator
using the LT1945. As for the boost inductor selection,
a larger or smaller value can be used. For designs with
Ceramic capacitors also make a good choice for the input
decoupling capacitor, which should be placed as close
as possible to the LT1945. A 4.7μF input capacitor is
sufficient for most applications. Table 2 shows a list of
severalcapacitormanufacturers.Consultthemanufacturers
varying V such as battery powered applications, use the
IN
minimum V value in the equation below.
IN
VOUT − VIN MIN) + VD
(
L =
tOFF
for more detailed information and for their entire selection
ILIM
1945fa
6
LT1945
APPLICATIONS INFORMATION
of related parts.
Diode Selection
For most LT1945 applications, the Zetex ZHCS400 sur-
face mount Schottky diode (0.4A, 40V) is an ideal choice.
Schottky diodes, with their low forward voltage drop and
fast switching speed, are the best match for the LT1945.
TheMotorolaMBR0520,MBR0530,orMBR0540canalso
be used. Many different manufacturers make equivalent
parts, but make sure that the component is rated to handle
at least 0.35A.
Table 2. Recommended Capacitors
CAPACITOR TYPE
VENDOR
Ceramic
Taiyo Yuden
(408) 573-4150
www.t-yuden.com
Ceramic
Ceramic
AVX
(803) 448-9411
www.avxcorp.com
Murata
(714) 852-2001
www.murata.com
Lowering Output Voltage Ripple
Setting the Output Voltages
Using low ESR capacitors will help minimize the output
ripple voltage, but proper selection of the inductor and the
outputcapacitoralsoplaysabigrole.TheLT1945provides
energy to the load in bursts by ramping up the inductor
current, thendeliveringthatcurrenttotheload. Iftoolarge
of an inductor value or too small of a capacitor value is
used, the output ripple voltage will increase because the
capacitor will be slightly overcharged each burst cycle.
To reduce the output ripple, increase the output capacitor
valueoradda4.7pFfeed-forwardcapacitorinthefeedback
network of the LT1945 (see the circuits in the Typical Ap-
plications section). Adding this small, inexpensive 4.7pF
capacitor will greatly reduce the output voltage ripple.
Set the output voltage for Switcher 1 (negative output
voltage ) by choosing the appropriate values for feedback
resistors R1 and R2.
VOUT –1.23V
R1=
1.23V
+ 2•10−6
(
)
R2
Set the output voltage for Switcher 2 (positive output
voltage) by choosing the appropriate values for feedback
resistors R1B and R2B (see Figure 1).
V
1.23
⎛
⎝
⎞
⎠
R1=R2 OUT −1
⎜
⎟
PACKAGE DESCRIPTION
MS Package
10-Lead Plastic MSOP
3.00 p 0.102
(.118 p .004)
(NOTE 3)
(Reference LTC DWG # 05-08-1661)
0.889 p 0.127
(.035 p .005)
0.497 p 0.076
(.0196 p .003)
REF
10 9
8
7 6
5.23
3.00 p 0.102
(.118 p .004)
NOTE 4
3.2 – 3.45
(.206)
4.88 p 0.10
(.192 p .004)
(.126 – .136)
MIN
DETAIL “A”
0.254
(.010)
0o – 6o TYP
GAUGE PLANE
0.50
(.0197)
BSC
0.305 p 0.038
(.0120 p .0015)
TYP
1
2
3
4 5
0.53 p 0.01
(.021 p .006)
RECOMMENDED SOLDER PAD LAYOUT
0.86
(.034)
REF
1.10
(.043)
MAX
DETAIL “A”
0.18
(.007)
SEATING
PLANE
NOTE:
0.17 – 0.27
(.007 – .011)
0.13 p 0.05
(.005 p .002)
MSOP (MS) 0402
1. DIMENSIONS IN MILLIMETER/(INCH)
2. DRAWING NOT TO SCALE
0.50
(.0197)
TYP
3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS.
MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.
INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE
5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX
1945fa
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.
7
LT1945
TYPICAL APPLICATIONS
Dual Output ( 32V) Converter
Efficiency at VIN = 3.6V
C4
L1
80
75
70
65
60
55
50
0.1μF
D1
10μH
V
IN
–32V
5mA
+32V OUTPUT
2.7V
TO 5V
8
10
SW1
100pF
604k
V
IN
–32V OUTPUT
2
4
1
5
SHDN1
NFB1
C1
4.7μF
C2
1μF
LT1945
D2
SHDN2
FB2
24.9k
GND PGND PGND SW2
3
7
9
6
80.6k
2M
0.1
1
10
C3
1μF
LOAD CURRENT (mA)
4.7pF
D3
1945 TA02a
L2
10μH
32V
5mA
1945 TA02
C1: TAIYO YUDEN JMK212BJ475
(408)573-4150
C2, C3: TAIYO YUDEN GMK316BJ105 (408)573-4150
C4: TAIYO YUDEN UMK212BJ104
D1, D2, D3: ZETEX ZHCS400
L1, L2: MURATA LQH3C100
(408)573-4150
(631)543-7100
(814)237-1431
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PART NUMBER
DESCRIPTION
COMMENTS
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Dual Output 350mA I , Constant Off-Time, High Efficiency
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V
V
= 1.2V to 15V, V
= 34V, I = 20μA, I = <1μA, MS Package
Q SD
SW
IN
IN
IN
OUT
Step-Up DC/DC Converter
LT1944-1
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= 1.2V to 15V, V
= 34V, I = 20μA, I = <1μA, MS Package
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550mA I , 600kHz/1.1MHz, High Efficiency
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SW
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LTC3400/LTC3400B 600mA I , 1.2MHz, Synchronous Step-Up DC/DC Converter
V
= 0.85V to 5V, V
= 5V, I = 19μA/300μA, I = <1μA,
OUT Q SD
SW
IN
ThinSOT Package
LTC3401
LTC3402
LTC3423
1A I , 3MHz, Synchronous Step-Up DC/DC Converter
V
V
V
= 0.5V to 5V, V
= 0.5V to 5V, V
= 0.5V to 5V, V
= 6V, I = 38μA, I = <1μA, MS Package
Q SD
SW
IN
IN
IN
OUT
OUT
OUT
2A I , 3MHz, Synchronous Step-Up DC/DC Converter
= 6V, I = 38μA, I = <1μA, MS Package
Q SD
SW
1A I , 3MHz, Low V , Synchronous Step-Up
= 6V, I = 38μA, I = <1μA, MS Package
Q SD
SW
OUT
DC/DC Converter
LTC3424
2A I , 3MHz, Low V , Synchronous Step-Up
V
= 0.5V to 5V, V
= 6V, I = 38μA, I = <1μA, MS Package
OUT Q SD
SW
OUT
IN
DC/DC Converter
1945fa
LT 1208 REV A • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
8
●
●
© LINEAR TECHNOLOGY CORPORATION 2001
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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