LTC4055EUF datasheet(21/24 Pages) LINER

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LTC4055

4055p

IN1

IN2

CHRG

ACPR

WALL

VNTC

NTC

OUT

Li-Ion

CELL

SUSPEND USB POWER

500mA/100mA SELECT

SHUTDOWN

µF

Ω

µF

TIMER PROG

LTC4055

CLPROG

GND

4055 F05

TO LDOs,

REGs, ETC

BAT

SUSP

HPWR

SHDN

CTIMER

0.1

µF

RPROG

61.9k

5V (NOM)

FROM USB

CABLE VBUS

5V WALL

ADAPTER INPUT

RCLPROG

105k

34.8k

10k

RNTCBIAS

100k

NTC

100k

Figure 5. USB Power Control Application with Wall Adapter Input

TYPICAL APPLICATIO S

LTC4055 Configured for USB Application with Wall

Adapter

Figure 5 shows an LTC4055 configured for USB applica-

tions with the optional wall adaptor input. The program-

ming resistor (RCLPROG) 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 VBUS to exceed the

500mA/100mA limits.

The programming resistor (RPROG) with a value of 61.9k

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.

LTC4055EUF Datasheet(PDF) 21 Page - Linear Technology

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