LTC3425 Datasheet, PDF (1/24 Pages) Linear Technology – 5A, 8MHz, 4-Phase Synchronous Step-Up DC/DC Converter

FEATURES
s _{High Efficiency: Up to 95%}
s _{Up to 3A Continuous Output Current}
s _{4-Phase Operation for Low Output Ripple}
and Tiny Solution Size
s _{Output Disconnect and Inrush Current Limiting}
s _{Very Low Quiescent Current: 12µA}
s _{0.5V to 4.5V Input Range}
s _{2.4V to 5.25V Adjustable Output Voltage}
s _{Adjustable Current Limit}
s _{Adjustable, Fixed Frequency Operation from}
100kHz to 2MHz per Phase
s _{Synchronizable Oscillator with Sync Output}
s _{Internal Synchronous Rectifiers}
s _{Manual or Automatic Burst Mode}^® _Operation
s _{Power Good Comparator}
s _{<1µA Shutdown Current}
s _{Antiringing Control}
s
5mm
×
5mm
Thermally
U
Enhanced
QFN
Package
APPLICATIO S
s _{Handheld Computers}
s _{Point-of-Load Regulators}
s _{3.3V to 5V Conversion}
LTC3425
5A, 8MHz, 4-Phase
Synchronous Step-Up
DC/DC Converter
DESCRIPTIO
The LTC^®3425 is a synchronous, 4-phase boost converter
with output disconnect capable of operation below 1V
input. It includes four N-channel MOSFET switches and
four P-channel synchronous rectifiers for an effective
R_DS(ON) of 0.045Ω and 0.05Ω, respectively. 4-phase
operation greatly reduces peak inductor currents, and
capacitor ripple current, and increases effective switching
frequency, minimizing inductor and capacitor sizes. True
output disconnect eliminates inrush current and allows
zero load current in shutdown. External Schottky diodes
are not required in most applications (V_OUT < 4.3V). Power
saving Burst Mode operation can be user controlled or left
in automatic mode.
Other features include 1µA shutdown current, program-
mable frequency with sync in and out, programmable
soft-start, antiringing control, thermal shutdown, adjust-
able current limit, reference output and power good
comparator.
The LTC3425 is available in a small, thermally enhanced
32-pin QFN package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Burst Mode is a registered trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
V_IN
2V TO 3V
2.2µF
2.7µH 2.7µH 2.7µH 2.7µH
OFF ON
0.01µF
15k
20k
75k
V_IN
SHDN
REFOUT
CCM
REFEN
SYNCIN
BURST
R_T
I_LIM
SGND
SWA
SWB
SWC
SWD
V_OUTS
V_OUTA
V_OUTB
V_OUTC
V_OUTD
LTC3425
GNDA
GNDB
FB
COMP
SS
SYNCOUT
PGOOD
GNDC GNDD
4.7µF
×4
1M
V_OUT
3.3V
2A
10k
22pF
330pF
590k
33k
0.01µF
C_IN: TAIYO YUDEN JMK107BJ225MA
C_OUT: TAIYO YUDEN JMK212BJ475MG (×4)
L1-L4: TDK RLF5018T-2R7M1R8
3425 TA01
100
90
80
Burst Mode FIXED
70
OPERATION FREQUENCY
MODE
60
50
40
30
20
V_IN = 2.4V
V_OUT = 3.3V
10 ^{f = 1MHz/PHASE}
L = 2.7µH
0
0.1
1
10
100 1000 10000
LOAD CURRENT (mA)
3425 TA02
3425f
1