LT3684 Datasheet, PDF (1/24 Pages) Linear Technology – 36V, 2A, 2.8MHz Step-Down Switching Regulator

LT3684
36V, 2A, 2.8MHz Step-Down
Switching Regulator
FEATURES
■ _{Wide Input Range: 3.6V to 34V Operating,}
36V Maximum
■ _{2A Maximum Output Current}
■ _{Adjustable Switching Frequency: 300kHz to 2.8MHz}
■ _{Low Shutdown Current: IQ < 1µA}
■ _{Integrated Boost Diode}
■ _{Power Good Flag}
■ _{Saturating Switch Design: 0.18Ω On-Resistance}
■ _{1.265V Feedback Reference Voltage}
■ _{Output Voltage: 1.265V to 20V}
■ _{Soft-Start Capability}
■ _{Small 10-Pin Thermally Enhanced MSOP and}
(3mm × 3mm) DFN Packages
APPLICATIONS
■ _{Automotive Battery Regulation}
■ _{Power for Portable Products}
■ _{Distributed Supply Regulation}
■ _{Industrial Supplies}
■ _{Wall Transformer Regulation}
DESCRIPTION
The LT^®3684 is an adjustable frequency (300kHz to 2.8MHz)
monolithic buck switching regulator that accepts input
voltages up to 34V (36V maximum). A high efficiency
0.18Ω 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 LT3684’s
high operating frequency allows the use of small, low cost
inductors and 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). A power good flag signals when V_OUT reaches
90% of the programmed output voltage. The LT3684 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
3.3V Step-Down Converter
V_IN
4.5V TO
34V
V_IN
BD
V_OUT
3.3V
2A
4.7µF
OFF ON
16.2k
330pF
RUN/SS
BOOST
V_C
SW
LT3684
RT
0.47µF 4.7µH
PG
60.4k
BIAS
GND
FB
324k
200k
22µF
3684 TA01
Efficiency
90
80
70
60
50
40
30
0
V_IN = 12V
V_OUT = 3.3V
L = 4.7µH
f = 800kHz
0.5
1
1.5
2
LOAD CURRENT (A)
3684 TA01b
3684f
1