LTC3455_15 Datasheet, PDF (25/28 Pages) Linear Technology – Dual DC/DC Converter with USB Power Manager and Li-Ion Battery Charger

LTC3455/LTC3455-1
TYPICAL APPLICATIONS
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.
USB 5V
1Ω
C6
4.7μF
5.6V
USB
CONTROLLER
8
USB
6
SUSPEND
5
USBHP
C5
10μF
10
V_MAX
21
MODE
15
HSON
19
ON2
22
PWRON
RST ²⁰
23
PBSTAT
LTC3455/LTC3455-1
1M 1M
μC
1.8V
4 _CHRG
11 _WALLFB
3
V_MAX
2
2.49k
9
C4
4700μF
1.8V
DROPOUT
10k
17
V_MAX
82.5k
1M
16
20k
TIMER
PROG
V_BAT
AO
AI
ON ²⁴
ON/OFF
14
HSO
3.3V, HS
C3
1μF
13
HSI
12 ^{L2, 4.7μH}
SW2
3.3V
0.4A
10pF
18
FB2
249k
C2
10μF
80.6k
7 ^{L1, 4.7μH}
SW1
10pF
1
FB1
25
GND
1.8V
0.2A
100k
C1
10μF
80.6k
3455 F16
C1, C2, C3, C5, C6: X5R OR X7R CERAMIC
L1, L2: TOKO DB318C
ALL RESISTORS 1%
Figure 16. Standalone USB Power Supply with Temporary Backup Power
3455fc
25