LT3470A
Micropower Buck Regulator
with Integrated Boost and
Catch Diodes
FEATURES
DESCRIPTION
The LT®3470A is a micropower step-down DC/DC con-
verter that integrates a 440mA power switch, catch diode
and boost diode into low profile 2mm × 3mm DFN
package. The LT3470A combines Burst Mode and
continuous operation to allow the use of tiny inductor
and capacitors while providing a low ripple output to
loads of up to 250mA.
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Low Quiescent Current: 35μA at 12V to 3.3V
IN
OUT
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Integrated Boost and Catch Diodes
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Input Range: 4V to 40V
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3.3V at 250mA from 4V to 40V Input
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5V at 250mA from 5.7V to 40V Input
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Low Output Ripple: <10mV
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<1μA in Shutdown Mode
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Output Voltage: 1.25V to 16V
With its wide input range of 4V to 40V, the LT3470A can
regulateawidevarietyofpowersources,from2-cellLi-Ion
batteries to unregulated wall transformers and lead-acid
batteries. Quiescent current in regulation is just 35μA in
a typical application while a zero current shutdown mode
disconnects the load from the input source, simplifying
powermanagementinbattery-poweredsystems.Fastcur-
rent limiting and hysteretic control protects the LT3470A
and external components against shorted outputs, even
at 40V input. The LT3470A has higher output current and
improved start-up and dropout performance compared
to the LT3470.
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Hysteretic Mode Control
– Low Ripple Burst Mode® Operation at Light Loads
– Continuous Operation at Higher Loads
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Solution Size as Small as 50mm
Low Profile (0.75mm) 2mm × 3mm Thermally
Enhanced 8-Lead DFN Package
APPLICATIONS
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Automotive Battery Regulation
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Power for Portable Products
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Distributed Supply Regulation
L, 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.
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Industrial Supplies
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Wall Transformer Regulation
TYPICAL APPLICATION
Efficiency and Power Loss vs Load Current
90
80
70
60
50
40
30
20
10
1000
100
10
V
= 12V
IN
V
IN
5.7V TO 40V
0.22μF
33μH
V
BOOST
IN
LT3470A
SHDN
V
OUT
5V
OFF ON
2.2μF
SW
250mA
BIAS
604k
1%
22pF
FB
22μF
GND
200k
1%
1
3470a TA01
0.1
0.1
1
10
100
300
LOAD CURRENT (mA)
3470a TA02
3470afa
1