LTC3615-1_15 Datasheet, PDF (1/32 Pages) Linear Technology – Dual 4MHz, 3A Synchronous Step-Down DC/DC Converter

LTC3615/LTC3615-1
Features
Dual 4MHz, 3A Synchronous
Step-Down DC/DC Converter
Description
n _{High Efficiency: Up to 94%}
n _{Dual Outputs with 2 × 3A Output Current Capability}
n _{Low Output Ripple Burst Mode}^® _{Operation: IQ = 130µA}
n _{2.25V to 5.5V Input Voltage Range}
n _{±1% Output Voltage Accuracy}
n _{Output Voltages Down to 0.6V}
n _{Programmable Slew Rate at Switch Pins}
n _{Low Dropout Operation: 100% Duty Cycle}
n _{Shutdown Current ≤1µA}
n _{Adjustable Switching Frequency Up to 4MHz}
n _{Internal or External Compensation}
n _{Selectable Pulse-Skipping/Forced Continuous/}
Burst Mode Operation with Adjustable Burst Clamp
n _{Optional Active Voltage Positioning (AVP) with}
Internal Compensation
n _{Selectable 0°/90°/180° (LTC3615) or selectable}
140°/180° (LTC3615-1) Phase Shift Between Channels
n _{Fixed Internal and Programmable External Soft-Start}
n _{Accurate Start-Up Tracking Capability}
n _{DDR Memory Mode IOUT = ±1.5A}
n _{Available in 4mm × 4mm QFN-24 and TSSOP-24 Packages}
Applications
n _{Point-of-Load Supplies}
n _{Distributed Power Supplies}
n _{Portable Computer Systems}
n _{DDR Memory Termination}
n _{Handheld Devices}
The LTC^®3615/LTC3615-1 are dual 3A synchronous step-
down regulators using a current mode, constant-frequency
architecture. The DC supply current is only 130µA (Burst
Mode operation at no-load) while maintaining the output
voltages, dropping to zero current in shutdown. The 2.25V
to 5.5V input supply range makes the parts ideally suited
for single Li-Ion applications. 100% duty cycle capability
provides low dropout operation, which extends operating
time in battery-operated systems.
The operating frequency is externally programmable up to
4MHz, allowing the use of small surface mount inductors.
0°, 90°, or 180° (LTC3615) or 140°/180° (LTC3615-1) of
phase shift between the two channels can be selected to
minimize input current ripple and output voltage ripple in a
dual 3A or single 6A output configuration. Programmable
slew rate limiting reduces EMI, and external synchroniza-
tion can be applied up to 4MHz.
The internal synchronous switches increase efficiency
and eliminate the need for external catch diodes, saving
external components and board space.
The LTC3615/LTC3615-1 are offered in leadless 24-pin
4mm × 4mm QFN and thermally enhanced 24-pin TSSOP
packages.
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.
Typical Application
V_IN
100µF
SV_IN PV_IN1
RUN1
TRACK/SS1
PGOOD1
ITH1
LTC3615
SRLIM
R_T/SYNC
MODE
PV_IN2
SW1
FB1
PHASE
RUN2
TRACK/SS2
PGOOD2
ITH2 SGND
SW2
FB2
PGND
3615 TA01a
0.47µH
0.47µH
422k
210k
665k
210k
V_OUT1
1.8V/3A
47µF
V_OUT2
2.5V/3A
47µF
Efficiency and Power Loss vs Load Current
100
10
90
80
1
70
60
0.1
50
40
0.01
30
20
10 ^2.25MHz
0 ^{VOUT = 2.5V}
0.001
0.01
0.1
V_IN = 3.3V
V_IN = 4V
V_IN = 5V
1
0.001
0.0001
OUTPUT CURRENT (A)
3615 TA01b
For more information www.linear.com/LTC3615
3615fb
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