LTC3407A
Dual Synchronous 600mA,
1.5MHz Step-Down
DC/DC Regulator
DESCRIPTION
FEATURES
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High Efficiency: Up to 96%
TheLTC®3407Aisadual,constantfrequency,synchronous
step-down DC/DC converter. Intended for low power ap-
plications, it operates from a 2.5V to 5.5V input voltage
range and has a constant 1.5MHz switching frequency,
enabling the use of tiny, low cost capacitors and inductors
1mm or less in height. Each output voltage is adjustable
from 0.6V to 5V. Internal synchronous 0.35Ω, 1A power
switches provide high efficiency without the need for
external Schottky diodes.
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Low Ripple (35mV ) Burst Mode Operation;
Q
1.5MHz Constant Frequency Operation
No Schottky Diodes Required
P-P
I = 40μA
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Low R
Internal Switches: 0.35Ω
DS(ON)
Current Mode Operation for Excellent Line
and Load Transient Response
Short-Circuit Protected
Low Dropout Operation: 100% Duty Cycle
Ultralow Shutdown Current: I < 1μA
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A user selectable mode input is provided to allow the user
to trade-off ripple noise for low power efficiency. Burst
Mode® operation provides the highest efficiency at light
loads, while Pulse Skip Mode provides the lowest ripple
noise at light loads.
Q
Output Voltages from 5V down to 0.6V
Power-On Reset Output
Externally Synchronizable Oscillator
Optional External Soft-Start
Small Thermally Enhanced MSOP and 3mm × 3mm
DFN Packages
To further maximize battery life, the P-channel MOSFETs
are turned on continuously in dropout (100% duty cycle),
and both channels draw a total quiescent current of only
40μA. In shutdown, the device draws <1μA.
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131.
APPLICATIONS
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PDAs/Palmtop PCs
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Digital Cameras
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Cellular Phones
Wireless and DSL Modems
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TYPICAL APPLICATION
1mm High 2.5V/1.8V at 600mA Step-Down Regulators
LTC3407A Efficiency/Power Loss Curve
100
1
V = 2.5V
IN
TO 5.5V
2.5V
90
1.8V
80
100k
10μF
0.1
RUN/SS2
V
IN
RUN/SS1
70
MODE/SYNC
POR
RESET
60
LTC3407A
50
40
0.01
0.001
0.0001
2.2μH
2.2μH
V
= 2.5V
V
= 1.8V
OUT1
OUT2
SW2
SW1
AT 600mA
AT 600mA
22pF
887k
22pF
30
20
V
= 3.3V
IN
Burst Mode OPERATION
V
FB1
V
10
0
FB2
NO LOAD ON OTHER CHANNEL
887k
GND
280k
442k
10μF
10μF
1
10
100
1000
LOAD CURRENT (mA)
3407A TA02
3407A TA01
3407afa
1