LT1912_15 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 circuitry.
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.
L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks
and ThinSOT is a trademark 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
1912fa
1