LTC3522_15 Datasheet, PDF (18/20 Pages) Linear Technology – Synchronous 400mA Buck-Boost and 200mA Buck Converters

LTC3522
TYPICAL APPLICATION
Li-Ion to 3V at 400mA and 1.2V at 200mA
V_IN
2.4V TO 4.2V ₊
Li-Ion
V_OUT2
1.2V
200mA
499k
COMBINED
PGOOD
OUTPUT
C1
10μF
C3
4.7μF
L1
6.8μH
PV_IN1 PV_IN2
SW2
SW1A
L2
4.7μH
12pF _102k
SW1B
LTC3522
FB2
V_OUT1
1M
100k
FB1
PGOOD2
PGOOD1
SHDN2
SHDN1
ON ^499k
OFF
PWM
BURST
PWM
C1: MURATA GRM219R61A475K (0805 PACKAGE)
C2, C3: MURATA GRM21BR60J106K (0805 PACKAGE)
L1: TAIYO YUDEN NPO35B-6R8M
L2: TAIYO YUDEN NPO35B-4R7M
PGND1 GND1 PGND2
3522 TA02
V_OUT1
3V
C2 ^300mA
4.7μF ^{(400mA, VIN > 3V)}
Buck-Boost Converter Efficiency vs Load Current
100
90 _{Burst Mode}
80 ^OPERATION
70
60
PWM Mode
50
40
30
20
1
V_IN = 4.2V
V_IN = 2.7V
10
100
LOAD CURRENT (mA)
1000
3522 TA02b
Buck Converter Efficiency vs Load Current
100
90
Burst Mode
OPERATION
80
70
PWM Mode
60
50
40
30
1
V_IN = 4.2V
V_IN = 2.7V
10
100
LOAD CURRENT (mA)
1000
3522 TA02c
3522fa
18