LT1935
1.2MHz Boost DC/DC
Converter in ThinSOT
with 2A Switch
FEATURES
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DESCRIPTIO
1.2MHz Switching Frequency
High Output Voltage: Up to 38V
Wide Input Range: 2.3V to 16V
Low V
CESAT
Switch: 180mV at 2A
Soft-Start
Uses Small Surface Mount Components
5V at 1A from 3.3V Input
12V at 600mA from 5V Input
Low Shutdown Current: < 1µA
Pin-for-Pin Compatible with the LT1613 and LT1930
Low Profile (1mm) SOT-23 (ThinSOT
TM
) Package
The LT
®
1935 is the industry’s highest power SOT-23
switching regulator. Its unprecedented 2A, 40V internal
switch allows high output currents to be generated in a
small footprint. Intended for space-conscious applica-
tions, the LT1935 switches at 1.2MHz, allowing the use of
tiny, low profile inductors and capacitors 2mm or less in
height. The NPN switch achieves a V
CESAT
of just 180mV
at 2A independent of supply voltage, resulting in high
efficiency even at maximum power levels from a 3V input.
A constant frequency, internally compensated, current
mode PWM architecture results in low, predictable output
noise that is easy to filter. Low ESR ceramic capacitors can
be used on the output, further reducing noise to the
millivolt level. The high voltage switch on the LT1935 is
rated at 40V, making the device ideal for boost converters
up to 38V as well as for single-ended primary inductance
converter (SEPIC) and flyback designs. The device can
generate 5V at up to 1A from a 3.3V supply or 5V at 550mA
from four alkaline cells in a SEPIC design.
The LT1935 is available in a 5-lead SOT-23 package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
APPLICATIO S
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Digital Cameras
Battery Backup
LCD Bias
Local 5V or 12V Supply
PC Cards
xDSL Power Supply
TFT-LCD Bias Supply
TYPICAL APPLICATIO
V
IN
5V
4.7µF
V
IN
LT1935
L1
4.2µH
D1
90
V
OUT
12V
600mA
85
80
SW
EFFICIENCY (%)
84.5k
10µF
75
70
65
60
ON OFF
SHDN
GND
FB
10k
D1: ON SEMI MBRM120
L1: SUMIDA CDRH5D28-4R2
1935 F01
55
50
0
100
200
300
400
500
600
700
LOAD CURRENT (mA)
1935 F01b
Figure 1. 5V to 12V, 600mA Step-Up DC/DC Converter
U
Efficiency, V
OUT
= 12V
V
IN
= 5V
V
IN
= 3.3V
1935f
U
U
1
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
