LTC3456 Datasheet, PDF (13/28 Pages) Linear Technology – 2-Cell, Multi-Output DC/DC Converter with USB Power Manager

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OPERATIO
AC Wall Adapter Powered
The LTC3456 can be powered off the AC wall adapter as
shown in Figure 3. The wall adapter is connected to the
V_EXT pin via the diode D1.
The status of the AC wall adapter power is monitored
through the WALLFB pin. The nominal voltage at this pin
is 1.25V. When the pin voltage is higher than 1.25V, the IC
LTC3456
will draw all its power from the AC adapter via the V_EXT pin.
The WALLFB voltage should always be kept below 2V.
When enabled, the onboard voltage detector checks the
status of the V_EXT voltage. If the V_EXT pin voltage is greater
than 4V, the V_INT, Core output, Main output and Hot Swap
outputs power-up in that sequence.
V_EXT
AC
ADAPTER
5V ±5%
–
4V
+
V_EXT
9
10µF
LTC3456
EN
BUCK 1
SW1
5
SW2_BK
D1
BUCK 2
13
WALL_RDY
V_INT
15
V_MAIN
16
L1
10µH
L3
10µH
11.3k
4.32k
WALLFB
7
1.25V
R
–
+^VOS
HSO
17
3456 F03
Figure 3. AC Adapter-Powered LTC3456
10µF
CORE OUTPUT
1.8V
200mA
V_INT
3.3V
22µF
MAIN OUTPUT
3.3V
1µF ^150mA
Hot Swap OUTPUT
3.3V
1µF ^50mA
3456fa
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