ltc3523-ltc3523-2 Linear Technology Corporation, ltc3523-ltc3523-2 Datasheet - Page 12

• Manufacturer Part Number: ltc3523-ltc3523-2
• Description: Synchronous 600ma Step-up And 400ma Step-down Dc/dc Converters
• Manufacturer: Linear Technology Corporation

LTC3523/LTC3523-2
DUAL BUCK-BOOST AND STEP-UP CONVERTER
OPERATION
The LTC3523/LTC3523-2 can be operated in a cascaded
confi guration as shown in Figure 2, allowing buck-boost
and step-up converter operation. Supply rail sequencing
is achieved by feeding the step-up converter PGOOD1
APPLICATIONS INFORMATION
12
1.8V TO 5.25V
STEP-UP
OUTPUT
100mA
V
OUT1
V
5V
IN
10μF
768k
243k
Figure 2. Dual Converter Effi ciency (Load Applied
to Step-Down Output)
4.7μF
OFF ON
100
90
80
70
60
50
40
30
20
10
0
0.1
10μF
SW1
V
FB1
PGOOD1
SHDN1
OUT
OUTPUT CURRENT (mA)
1
GND1 GND2 GND3
V
IN1
5V OUTPUT
LTC3523
V
10
IN2
into the step-down’s ⎯ S ⎯ H ⎯ D ⎯ N ⎯ 2 pin. Note that the overall
3.3V converter effi ciency is the product of the individual
effi ciencies.
3.3V OUTPUT
V
V
V
V
f
BURST ENABLED
PGOOD2
OSC
BAT
IN
OUT1
OUT2
SHDN2
MODE
= 2.4V
SW2
100
= 1.2MHz
FB2
= 5V
= 3.3V
3523 F02b
4.7μF
V
IN
100k
1000
3523 F02a
V
IN
10pF
825k
182k
10μF
V
STEP-DOWN
OUTPUT
3.3V
50mA
OUT2
3523f