LTC3633_15 Datasheet, PDF (1/28 Pages) Linear Technology – Dual Channel 3A, 15V Monolithic Synchronous Step-Down Regulator

FEATURES
n _{3.6V to 15V Input Voltage Range}
n _{3A Output Current per Channel}
n _{Up to 95% Efficiency}
n _{Low Duty Cycle Operation: 5% at 2.25MHz}
n _{Selectable 0°/180° Phase Shift Between Channels}
n _{Adjustable Switching Frequency: 500kHz to 4MHz}
n _{External Frequency Synchronization}
n _{Current Mode Operation for Excellent Line and}
Load Transient Response
n _{0.6V Reference Allows Low Output Voltages}
n _{User Selectable Burst Mode}^® _{Operation or Forced}
Continuous Operation
n _{Output Voltage Tracking and Soft-Start Capability}
n _{Short-Circuit Protected}
n _{Overvoltage Input and Overtemperature Protection}
n _{Low Power 2.5V Linear Regulator Output}
n _{Power Good Status Outputs}
n _{Available in (4mm × 5mm) QFN-28 and 28-Lead}
TSSOP Packages
APPLICATIONS
n _{Distributed Power Systems}
n _{Battery Powered Instruments}
n _{Point of Load Power Supplies}
LTC3633
Dual Channel 3A, 15V
Monolithic Synchronous
Step-Down Regulator
DESCRIPTION
The LTC^®3633 is a high efficiency, dual-channel monolithic
synchronous buck regulator using a controlled on-time,
current mode architecture, with phase lockable switching
frequency. The two channels can run 180° out of phase,
which relaxes the requirements for input and output ca-
pacitance. The operating supply voltage range is from 3.6V
to 15V, making it suitable for dual cell lithium-ion batteries
as well as point of load power supply applications from
a 12V or 5V supply.
The operating frequency is programmable and synchroniz-
able from 500kHz to 4MHz with an external resistor. The
high frequency capability allows the use of small surface
mount inductors and capacitors. The unique constant
frequency/controlled on-time architecture is ideal for high
step-down ratio applications that operate at high frequency
while demanding fast transient response. An internal phase
lock loop servos the on-time of the internal one-shot timer
to match the frequency of the internal clock or an applied
external clock.
The LTC3633 can select between forced continuous mode
and high efficiency Burst Mode operation.
L, LT, LTC, LTM, Burst Mode, Linear Technology 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, 5847554, 6580258, 6304066, 6476589,
6774611.
TYPICAL APPLICATION
V_IN
12V
47µF
x2
V_OUT2
5V AT 3A
22µF
1.5µH 0.1µF
73.2k
10k
RUN1 ^VIN2
RUN2
V_{IN1 INTVCC}
ITH1
ITH2
LTC3633
RT
MODE/SYNC
PHMODE
V2P5
TRACKSS2
TRACKSS1
PGOOD2
PGOOD1
BOOST2
BOOST1
SW2
V_ON2
V_{FB2 SGND PGND}
SW1
V_ON1
V_FB1
2.2µF
0.1µF 1µH
45.3k
10k
V_OUT1
3.3V AT 3A
22µF
3633 TA01a
For more information www.linear.com/LTC3633
Efficiency vs Load Current
100
100
Burst Mode
90 OPERATION
80
10
70
60
1
50
40
0.1
30
20
0.01
10
V_IN = 12V
0
1
10
V_OUT = 5V
V_OUT = 3.3V
0.001
100
1000 10000
LOAD CURRENT (mA)
3633 TA01b
3633fd
1