LT1935
1.2MHz Boost DC/DC
Converter in ThinSOT
with 2A Switch
FEATURES
■ 1.2MHz Switching Frequency
■ High Output Voltage: Up to 38V
■ Wide Input Range: 2.3V to 16V
■ Low VCESAT 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 (ThinSOTTM) Package
U
APPLICATIO S
■ Digital Cameras
■ Battery Backup
■ LCD Bias
■ Local 5V or 12V Supply
■ PC Cards
■ xDSL Power Supply
■ TFT-LCD Bias Supply
DESCRIPTIO
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 VCESAT 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.
TYPICAL APPLICATIO
L1
VIN
4.2µH
D1
5V
4.7µF
ON OFF
VIN SW
LT1935
SHDN
FB
GND
84.5k
10k
VOUT
12V
600mA
10µF
D1: ON SEMI MBRM120
L1: SUMIDA CDRH5D28-4R2
1935 F01
Figure 1. 5V to 12V, 600mA Step-Up DC/DC Converter
www.DataSheet4U.com
Efficiency, VOUT = 12V
90
85 VIN = 5V
80 VIN = 3.3V
75
70
65
60
55
50
0 100 200 300 400 500 600 700
LOAD CURRENT (mA)
1935 F01b
1935f
1
