LT3480
36V, 2A, 2.4MHz Step-Down
Switching Regulator with
70µA Quiescent Current
DESCRIPTION
FEATURES
The LT®3480 is an adjustable frequency (200kHz to
2.4MHz) monolithic buck switching regulator that ac-
cepts input voltages up to 36V (60V maximum). A high
efficiency 0.25 switch is included on the die along with
a boost Schottky diode and the necessary oscillator, con-
trol, and logic circuitry. Current mode topology is used
for fast transient response and good loop stability. Low
ripple Burst Mode operation maintains high efficiency at
low output currents while keeping output ripple below
15mV in a typical application. In addition, the LT3480 can
further enhance low output current efficiency by draw-
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Wide Input Range:
Operation from 3.6V to 36V
Over-Voltage Lockout Protects Circuits
through 60V Transients
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2A Maximum Output Current
Low Ripple Burst Mode® Operation
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70μA IQ at 12VIN to 3.3VOUT
Output Ripple < 15mV
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Adjustable Switching Frequency: 200kHz to 2.4MHz
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Low Shutdown Current: IQ < 1μA
Integrated Boost Diode
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Synchronizable Between 250kHz to 2MHz
ing bias current from the output when V
is above 3V.
OUT
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Power Good Flag
Shutdown 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
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Saturating Switch Design: 0.25 On-Resistance
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0.790V Feedback Reference Voltage
Output Voltage: 0.79V to 20V
Soft-Start Capability
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flag signals when V
reaches 86% of the programmed
OUT
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output voltage. The LT3480 is available in 10-Pin MSOP
and 3mm × 3mm DFN packages with exposed pads for
low thermal resistance.
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Small 10-Pin Thermally Enhanced MSOP and
(3mm × 3mm) DFN Packages
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners.
APPLICATIONS
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Automotive Battery Regulation
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Power for Portable Products
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Distributed Supply Regulation
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Industrial Supplies
TYPICAL APPLICATION
3.3V Step-Down Converter
Efficiency
V
V
3.3V
2A
100
IN
OUT
4.5V TO 36V
TRANSIENT
V = 5V
OUT
V
BD
IN
TO 60V
90
80
70
60
50
RUN/SS
BOOST
OFF ON
14k
V
= 3.3V
OUT
0.47μF
4.7μH
V
C
SW
LT3480
GND
4.7μF
RT
470pF
PG
316k
V
= 12V
40.2k
SYNC
FB
IN
L = 5.6μH
F = 800 kHz
100k
22μF
0
0.5
1.0
LOAD CURRENT (A)
1.5
2
3480 TA01
3480 TA01b
3480fb
1