LTC3521 Datasheet, PDF (18/20 Pages) Linear Technology – Wide VIN, 1A Buck-Boost DC/DC and Dual 600mA Buck DC/DC Converters

LTC3521
TYPICAL APPLICATION
Dual Supercapacitor to 3.3V at 200mA, 1.8V at 50mA and 1.2V at
100mA Backup Power Supply
V_IN
1.8V TO 5.5V
+
+
1F
1F
V_OUT1
3.3V
200mA
C1
22µF
C4
L1
4.7µF _4.7µH
R1
1.0M
R2
221k
ON
OFF
PWM
BURST
PV_IN1 PV_IN2
SW1A
SW2
SW1B
FB2
V_OUT1
LTC3521
FB1
SHDN1
SW3
SHDN2
SHDN3
FB3
PGOOD1
PWM
PGOOD2
PGOOD3
PGND1 GND PGND2
L2
4.7µH
L3
4.7µH
3521 TA02a
R3
137k
R4
68.1k
R5
100k
R6
100k
V_OUT2
1.8V
C2 _50mA
10µF
V_OUT3
1.2V
C3 _100mA
10µF
Converter Output Voltages
V_IN
2V/DIV
V_OUT1
2V/DIV
V_OUT2
2V/DIV
V_OUT3
2V/DIV
50µs/DIV
3521 TA02b
100
96
92
88
84
80
76
72
1.8
Efficiency vs V_IN
V_OUT1 = 3.3V
I_OUT = 200mA
V_OUT3 = 1.2V
I_OUT = 100mA
V_OUT2 = 1.8V
I_OUT = 50mA
2.8
3.8
V_IN (V)
4.8
3521 TA02c
3521f
18