LTC4055-1_15 Datasheet, PDF (21/24 Pages) Linear Technology – USB Power Controller and Li-Ion Charger

LTC4055/LTC4055-1
TYPICAL APPLICATIONS
LTC4055/LTC4055-1 Configured for USB Application
with Wall Adapter
Figure 5 shows an LTC4055/LTC4055-1 configured for
USB applications with the optional wall adapter input. The
programming resistor (R_CLPROG) is set to 105k which sets
up a nominal current limit of 467mA in high power mode
(92mA in low power). This is done to prevent the various
tolerances in the part and programming resistors from
allowing the input current supplied by V_BUS to exceed the
500mA/100mA limits.
The programming resistor (R_PROG) with a value of 60.4k
sets up a nominal charge current of approximately 800mA.
Note that this is the charge current when the wall adapter
is present. When the wall adapter is absent, the current
limit supersedes the charge current programming and
charge current is limited to 467mA.
5V WALL
ADAPTER INPUT
5V (NOM)
FROM USB
CABLE V_BUS
R3
1Ω
10μF
R1
34.8k
R2
10k
IN1
OUT
IN2
BAT ₊
CHRG
ACPR
LTC4055
SUSP
WALL
HPWR
R_NTCBIAS
100k
V_NTC
NTC
TIMER PROG
CLPROG
SHDN
GND
NTC
100k
C_TIMER
0.1μF
R_PROG R_CLPROG
60.4k 105k
Li-Ion
CELL
TO LDOs,
REGs, ETC
10μF
SUSPEND USB POWER
500mA/100mA SELECT
SHUTDOWN
4055 F05
Figure 5. USB Power Control Application with Wall Adapter Input
4055fb
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