Datasheet

LTC3455/LTC3455-1
25
3455fc
11
10
13
14
C3
1μF
C4
4700μF
WALLFB
HSI
HSO
C1, C2, C3, C5, C6: X5R OR X7R CERAMIC
L1, L2: TOKO DB318C
ALL RESISTORS 1%
3.3V, HS
V
MAX
8
6
5
9
1Ω
C6
4.7μF
USB 5V
USB
SUSPEND
USBHP
4
2
3
18
12
SW2
FB2
249k
L2, 4.7μH
80.6k
10pF
C2
10μF
3.3V
0.4A
1
7
SW1
FB1
100k
L1, 4.7μH
80.6k
10pF
C1
10μF
1.8V
0.2A
TIMER
PROG
16
AI
17
AO
DROPOUT
24
23
20
21
19
22
15
V
BAT
20k
10k
1M
1.8V
V
MAX
V
MAX
82.5k
C5
10μF
1M
2.49k
1M
1.8V
ON
25
GND
CHRG
PBSTAT
RST
MODE
LTC3455/LTC3455-1
ON2
PWRON
HSON
3455 F16
μC
USB
CONTROLLER
ON/OFF
5.6V
TYPICAL APPLICATIONS
Figure 16. Standalone USB Power Supply with Temporary Backup Power
using the battery charger to slowly charge this capacitor
(normally using such a large capacitor would result in
very large inrush currents). With the TIMER pin tied to
V
MAX
, the battery charger operates in constant-current
mode (the voltage-loop and timer function are disabled),
so the 4700μF capacitor is always fully charged to the
available USB voltage.