LT1912 Datasheet, PDF (1/24 Pages) Linear Technology – 36V, 2A, 500kHz Step-Down Switching Regulator

LT1912
36V, 2A, 500kHz Step-Down
Switching Regulator
FEATURES
■ _{Wide Input Range:}
Operation From 3.6V to 36V
■ _{2A Maximum Output Current}
■ _{Adjustable Switching Frequency: 200kHz to 500kHz}
■ _{Low Shutdown Current: IQ < 1μA}
■ _{Integrated Boost Diode}
■ _{Synchronizable Between 250kHz to 500kHz}
■ _{Saturating Switch Design: 0.25Ω On-Resistance}
■ _{0.790V Feedback Reference Voltage}
■ _{Output Voltage: 0.79V to 20V}
■ _{Soft-Start Capability}
■ _{Small 10-Pin Thermally Enhanced MSOP and}
(3mm × 3mm) DFN Packages
APPLICATIONS
■ _{Automotive Battery Regulation}
■ _{Set Top Box}
■ _{Distributed Supply Regulation}
■ _{Industrial Supplies}
■ _{Wall Transformer Regulation}
DESCRIPTION
The LT^®1912 is an adjustable frequency (200kHz to
500kHz) monolithic step-down switching regulator that
accepts input voltages up to 36V. A high efficiency 0.25Ω
switch is included on the die along with a boost Schottky
diode and the necessary oscillator, control, and logic cir-
cuitry. Current mode topology is used for fast transient
response and good loop stability. The LT1912 allows the
use of ceramic capacitors resulting in low output ripple
while keeping total solution size to a minimum. The low
current shutdown mode reduces input supply current
to less than 1μA while a resistor and capacitor on the
RUN/SS pin provide a controlled output voltage ramp
(soft-start). The LT1912 is available in 10-Pin MSOP and
3mm × 3mm DFN packages with exposed pads for low
thermal resistance.
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
TYPICAL APPLICATION
V_IN
4.5V TO 36V
3.3V Step-Down Converter
OFF ON
V_IN
RUN/SS
BD
BOOST
20k
4.7μF
470pF
V_C
LT1912
SW
R_T
68.1k
SYNC
GND
FB
V_OUT
3.3V
2A
0.47μF _6.8μH
316k
100k
47μF
1912 TA01
Efficiency
100
V_OUT = 5V
90
80
V_OUT = 3.3V
70
60
V_IN = 12V
L = 6.8μF
50
F = 500kHz
0 0.5
1.0
1.5
2
LOAD CURRENT (A)
1912 TA01b
1912f
1