LTC3615
Dual 4MHz, 3A Synchronous
Step-Down DC/DC Converter
DescripTion
FeaTures
TheLTC®3615isadual3Asynchronousstep-downregula-
torusingacurrentmode,constant-frequencyarchitecture.
TheDCsupplycurrentisonly130µA(BurstModeoperation
at no-load) while maintaining the output voltages, drop-
ping to zero current in shutdown. The 2.25V to 5.5V input
supply range makes the LTC3615 ideally suited for single
Li-Ion applications. 100% duty cycle capability provides
low dropout operation, which extends operating time in
battery-operated systems.
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High Efficiency: Up to 94%
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Dual Outputs with 2 × 3A Output Current Capability
Low Output Ripple Burst Mode® Operation:I = 130µA
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Q
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2.25V to 5.5V Input Voltage Range
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1% Output Voltage Accuracy
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Output Voltages Down to 0.6V
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Programmable Slew Rate at Switch Pins
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Low Dropout Operation: 100% Duty Cycle
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Shutdown Current ≤1µA
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Adjustable Switching Frequency Up to 4MHz
The operating frequency is externally programmable up to
4MHz, allowing the use of small surface mount inductors.
0°, 90°, or 180° of phase shift between the two channels
can be selected to minimize input current ripple and
output voltage ripple in a single 6A output configuration.
ProgrammableslewratelimitingreducesEMI,andexternal
synchronization can be applied up to 4MHz.
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Internal or External Compensation
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Selectable Pulse-Skipping/Forced Continuous/
Burst Mode Operation with Adjustable Burst Clamp
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Optional Active Voltage Positioning (AVP) with
Internal Compensation
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Selectable 0°/90°/180° Phase Shift Between Channels
Fixed Internal and Programmable External Soft-Start
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The internal synchronous switches increase efficiency
and eliminate the need for external catch diodes, saving
external components and board space.
Accurate Start-Up Tracking Capability
DDR Memory Mode I = 1.5A
OUT
Availablein 4mm×4mm QFN-24andTSSOP-24Packages
The LTC3615 is offered in leadless 24-pin 4mm × 4mm
applicaTions
QFN and thermally enhanced 24-pin TSSOP packages.
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Point-of-Load Supplies
L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners. Protected by U.S. Patents, including 5481178, 5994885, 6304066, 6498466, 6580258,
6611131.
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Distributed Power Supplies
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Portable Computer Systems
DDR Memory Termination
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Handheld Devices
Efficiency and Power Loss vs Load Current
Typical applicaTion
100
90
80
70
60
50
40
30
20
10
0
10
V
IN
100µF
SV
IN
RUN1
PV
IN1
PV
IN2
SW1
0.47µH
0.47µH
V
1
OUT1
1.8V/3A
TRACK/SS1
PGOOD1
ITH1
47µF
422k
210k
0.1
LTC3615
FB1
SRLIM
R /SYNC
T
0.01
0.001
0.0001
MODE
V
OUT2
2.5V/3A
SW2
PHASE
47µF
RUN2
665k
210k
V
V
V
= 3.3V
= 4V
= 5V
IN
IN
IN
TRACK/SS2
PGOOD2
2.25MHz
= 2.5V
FB2
V
OUT
ITH2 SGND PGND
0.001
0.01
0.1
1
3615 TA01a
OUTPUT CURRENT (A)
3615 TA01b
3615f
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