LT1613
1.4MHz, Sing le Ce ll DC/ DC
Co nve rte r in 5-Le a d SOT-23
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DESCRIPTIO
FEATURES
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Uses Tiny Capacitors and Inductor
Internally Compensated
Fixed Frequency 1.4MHz Operation
The LT®1613 is the industry’s first 5-lead SOT-23 current
mode DC/DC converter. Intended for small, low power
applications, it operates from an input voltage as low as
1.1V and switches at 1.4MHz, allowing the use of tiny, low
cost capacitors and inductors 2mm or less in height. Its
small size and high switching frequency enables the
complete DC/DC converter function to take up less than
0.2 square inches of PC board area. Multiple output power
supplies can now use a separate regulator for each output
voltage, replacing cumbersome quasi-regulated ap-
proaches using a single regulator and a custom trans-
former.
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Operates with V as Low as 1.1V
IN
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3V at 30mA from a Single Cell
5V at 200mA from 3.3V Input
15V at 60mA from Four Alkaline Cells
High Output Voltage: Up to 34V
Low Shutdown Current: <1µA
Low VCESAT Switch: 300mV at 300mA
Tiny 5-Lead SOT-23 Package
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A constant frequency, internally compensated current
mode PWM architecture results in low, predictable output
noise that is easy to filter. The high voltage switch on the
LT1613 is rated at 36V, making the device ideal for boost
converters up to 34V as well as for Single-Ended Primary
Inductance Converter (SEPIC) and flyback designs. The
device can generate 5V at up to 200mA from a 3.3V supply
or 5V at 175mA from four alkaline cells in a SEPIC design.
APPLICATIO S
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Digital Cameras
Pagers
Cordless Phones
Battery Backup
LCD Bias
Medical Diagnostic Equipment
Local 5V or 12V Supply
External Modems
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The LT1613 is available in the 5-lead SOT-23 package.
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, LTC and LT are registered trademarks of Linear Technology Corporation.
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PC Cards
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TYPICAL APPLICATIO
L1
4.7µH
Efficiency Curve
D1
100
95
V
3.3V
V
OUT
5V
200mA
IN
R1
37.4k
V
SW
FB
IN
90
V
= 4.2V
= 3.5V
IN
+
+
C1
15µF
C2
22µF
85
80
75
70
65
60
55
50
LT1613
V
IN
SHDN
SHDN
GND
V
IN
= 2.8V
R2
12.1k
V
IN
= 1.5V
L1: MURATA LQH3C4R7M24 OR SUMIDA CD43-4R7
C1: AVX TAJA156M010
C2: AVX TAJB226M006
1613 TA01
D1: MBR0520
0
50 100 150 200 250 300 350 400
LOAD CURRENT (mA)
Figure 1. 3.3V to 5V 200mA DC/DC Converter
1613 TA01a
1