LT1933
600mA, 500kHz Step-Down
Switching Regulator in
SOT-23 and DFN Packages
FEATURES
DESCRIPTION
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The LT ®1933 is a current mode PWM step-down DC/DC
converter with an internal 0.75A power switch, packaged
in a tiny 6-lead SOT-23. The wide input range of 3.6V
to 36V makes the LT1933 suitable for regulating power
from a wide variety of sources, including unregulated wall
transformers, 24V industrial supplies and automotive
batteries. Its high operating frequency allows the use of
tiny, low cost inductors and ceramic capacitors, resulting
in low, predictable output ripple.
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Wide Input Range: 3.6V to 36V
5V at 600mA from 16V to 36V Input
3.3V at 600mA from 12V to 36V Input
5V at 500mA from 6.3V to 36V Input
3.3V at 500mA from 4.5V to 36V Input
Fixed Frequency 500kHz Operation
Uses Tiny Capacitors and Inductors
Soft-Start
Internally Compensated
Low Shutdown Current: <2μA
Output Adjustable Down to 1.25V
Low Profile (1mm) SOT-23 (ThinSOT™) and
(2mm × 3mm × 0.75mm) 6-Pin DFN Packages
Cycle-by-cycle current limit provides protection against
shorted outputs, and soft-start eliminates input current
surge during start up. The low current (<2μA) shutdown
provides output disconnect, enabling easy power management in battery-powered systems.
APPLICATIONS
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L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
Automotive Battery Regulation
Industrial Control Supplies
Wall Transformer Regulation
Distributed Supply Regulation
Battery-Powered Equipment
TYPICAL APPLICATION
Efficiency
95
3.3V Step-Down Converter
SHDN
GND
0.1μF
22μH
SW
FB
16.5k
2.2μF
VOUT = 5V
BOOST
LT1933
OFF ON
90
1N4148
VIN
10k
VOUT
3.3V/500mA
MBRM140
EFFICIENCY (%)
VIN
4.5V TO 36V
VIN = 12V
85
VOUT = 3.3V
80
75
22μF
70
1933 TA01a
65
0
100
200
300
400
LOAD CURRENT (mA)
500
600
1933 TA01b
1933fe
1
