LTC3417A-1
Dual Synchronous
1.5A/1A 4MHz Step-Down
DC/DC Regulator with POR
DESCRIPTION
FEATURES
The LTC®3417A-1 is a dual constant frequency, synchro-
nous step-down DC/DC converter. Intended for medium
power applications, it operates from a 2.25V to 5.5V input
voltagerangeandhasaconstantprogrammableswitching
frequency, allowing the use of tiny, low cost capacitors
and inductors 2mm or less in height. Each output voltage
is adjustable from 0.8V to 5V. Internal synchronous, low
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High Efficiency: Up to 95%
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1.5A/1A Guaranteed Minimum Output Current
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Synchronizable to External Clock
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Power-On-Reset Output
No Schottky Diodes Required
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Programmable Frequency Operation: 1.5MHz or
Adjustable From 0.6MHz to 4MHz
Low Ripple (< 35mV ) BurstMode® Operation
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R
power switches provide high efficiency without
DS(ON)
P-P
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the need for external Schottky diodes.
Low R
Internal Switches
DS(ON)
Short-Circuit Protected
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The open drain POR pin goes low when either output
voltage falls 6% below regulation. The output will remain
low 150ms longer than the duration of the out of regula-
tion condition.
V : 2.25V to 5.5V
IN
Current Mode Operation for Excellent Line and Load
Transient Response
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125μA Quiescent Current in Sleep Mode
A user selectable mode input allows the user to trade
off ripple voltage for light load efficiency. Burst Mode
operation provides high efficiency at light loads, while
pulse skip mode provides low ripple noise at light loads.
A phase mode pin allows the second channel to operate
in-phase or 180° out-of-phase with respect to channel 1.
Out-of-phase operation produces lower RMS current on
Ultralow Shutdown Current: I < 1μA
Q
Low Dropout Operation: 100% Duty Cycle
Phase Pin Selects 2nd Channel Phase Relationship
with Respect to 1st Channel
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Internal Soft-Start with Individual Run Pin Control
Available in Small Thermally Enhanced
(3mm × 5mm) DFN and 20-Lead TSSOP Packages
V and thus lower stress on the input capacitor.
IN
APPLICATIONS
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
100μA. In shutdown, the device draws <1μA.
L, LT, LTC and 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, 6144194.
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GPS/Navigation Systems
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Automotive Instrumentation
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PC Cards
Industrial Power Supplies
General Purpose Point of Load DC/DC
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OUT2 Efficiency
TYPICAL APPLICATION
(Burst Mode Operation)
V
100
95
90
85
80
75
70
10
IN
REFER TO FIGURE 4
2.5V TO 5.5V
10μF
100k
V
IN
1
RESET
POR
FREQ
SW1
EFFICIENCY
1.5μH
2.2μH
V
V
2.5V
1A
OUT1
1.8V
1.5A
OUT2
SW2
22pF
511k
22pF
0.1
RUN2
V
RUN1
V
IN
IN
LTC3417A-1
866k
0.01
0.001
0.0001
V
FB2
V
I
POWER LOSS
FB1
47μF
412k
5.9k
22μF
412k
V
V
= 3.6V
OUT
FREQ = 1MHz
I
IN
TH2
TH1
= 2.5V
2.87k
6800pF
GND
0.001
0.01
0.1
1
2200pF
LOAD CURRENT (A)
3417A-1 TA01
3417A-1 TA01a
3417a1fa
1