LTC3853 Datasheet, PDF (1/36 Pages) Linear Technology – Triple Output, Multiphase Synchronous Step-Down Controller

LTC3853
Triple Output,
Multiphase Synchronous
Step-Down Controller
FEATURES
DESCRIPTION
n _{Triple, 120° Phased Controllers Reduce Required}
Input Capacitance and Power Supply Induced Noise
n _{Configurable as a 180° Dual Phase Controller Plus a}
Single Phase Controller
n _{The Third Phase Can Regulate Up to a 13.5V Output}
n _{High Efficiency: Up to 92%}
n _{RSENSE or DCR Current Sensing}
n _{±0.75% 0.8V Output Voltage Accuracy}
n _{Phase-Lockable Fixed Frequency 250kHz to 750kHz}
n _{Supports Pre-Biased Outputs}
n _{Dual N-Channel MOSFET Synchronous Drive}
n _{Wide VIN Range: 4.5V to 24V Operation (28V Abs Max)}
n _{Adjustable Soft-Start Current Ramping or Tracking}
n _{Foldback Output Current Limiting}
n _{Output Overvoltage Protection}
n _{Dual Power Good Output Voltage Monitors}
n _{40-Lead 6mm × 6mm QFN Package}
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, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258.
The LTC^®3853 is a high performance triple output step-
down switching regulator controller that drives all N-chan-
nel synchronous power MOSFET stages. Power loss and
supply noise are minimized by operating the output stages
out of phase. The part can be configured as a dual phase
controller plus a single phase controller if needed. The
part can also be configured to provide a single 3-phase
output for even higher output currents.
A wide 4.5V to 24V (28V maximum) input voltage sup-
ply range encompasses most battery chemistries and
intermediate bus voltages. Phase 3 can regulate output
voltages up to 13.5V. A constant frequency current mode
architecture allows for a phase-lockable frequency up to
750kHz.
Independent TK/SS pins for each output ramps the output
voltages and can be configured for coincident or ratiometric
tracking. Current foldback limits MOSFET heat dissipation
during short-circuit conditions. The MODE/PLLIN pin
selects among Burst Mode^® operation, pulse-skipping or
continuous inductor current modes.
TYPICAL APPLICATION
High Efficiency Triple 5V/3.3V/1.2V Step-Down Converter
2.2μH
2.2k
0.1μF
V_OUT1
5V
5A
105k
+ _100μF
10V
220pF
20k
4.7μF
V_IN
INTV_CC
TG1
PGOOD12
PGOOD3
TG2
BOOST1,2,3
SW1
SW2
BG1 ^LTC3853 BG2
f_IN
500kHz
MODE/PLLIN
PGND
I_LIM
FREQ/PLLFLTR
SENSE1⁺
SENSE1^–
SENSE2⁺
SENSE2^–
V_FB2
1500pF
15k
V_FB1
I_TH1,2,3
RUN1,2,3
TG3
V_FB3
SGND
SW3
BG3
SENSE3⁺
SENSE3^–
TK/SS1,2,3
0.1μF
0.1μF
SW1,2,3
10nF
10k
2.2μH
2.2k
0.1μF
63.4k
20k
V_OUT2
3.3V
5A
100μF
6V
V_IN
7V TO 24V
22μF
50V
1μH
1k
0.1μF
10k
20k
V_OUT3
1.2V
5A
100μF
6V
3853f
1