LTC4085EDE-3-TRPBF Ver la hoja de datos (PDF) - Linear Technology

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LTC4085EDE-3-TRPBF

USB Power Manager with Ideal Diode Controller and 3.95V Li-Ion Charger

Linear Technology 

LTC4085-3/LTC4085-4

PIN FUNCTIONS

IN (Pin 1): Input Supply. Connect to USB supply, VBUS.

Input current to this pin is limited to either 20% or 100%

of the current programmed by the CLPROG pin as deter-

mined by the state of the HPWR pin. Charge current (to

BAT pin) supplied through the input is set to the current

programmed by the PROG pin but will be limited by the

input current limit if charge current is set greater than the

input current limit.

OUT (Pin 2): Voltage Output. This pin is used to provide

controlled power to a USB device from either USB VBUS

(IN) or the battery (BAT) when the USB is not present. This

pin can also be used as an input for battery charging when

the USB is not present and a wall adapter is applied to this

pin. OUT should be bypassed with at least 4.7μF to GND.

CLPROG (Pin 3): Current Limit Program and Input Cur-

rent Monitor. Connecting a resistor, RCLPROG, to ground

programs the input to output current limit. The current

limit is programmed as follows:

ICL

(A)

=

1000V

RCLPROG

In USB applications the resistor RCLPROG should be set

to no less than 2.1k.

The voltage on the CLPROG pin is always proportional to

the current flowing through the IN to OUT power path.

This current can be calculated as follows:

IIN(A) =

VCLPROG

RCLPROG

• 1000

HPWR (Pin 4): High Power Select. This logic input is used

to control the input current limit. A voltage greater than

1.2V on the pin will set the input current limit to 100% of

the current programmed by the CLPROG pin. A voltage

less than 0.4V on the pin will set the input current limit to

20% of the current programmed by the CLPROG pin. A 2μA

pull-down is internally applied to this pin to ensure it is low

at power up when the pin is not being driven externally.

SUSP (Pin 5): Suspend Mode Input. Pulling this pin above

1.2V will disable the power path from IN to OUT. The sup-

ply current from IN will be reduced to comply with the

USB specification for suspend mode. Both the ability to

charge the battery from OUT and the ideal diode function

(from BAT to OUT) will remain active. Suspend mode will

reset the charge timer if VOUT is less than VBAT while in

suspend mode. If VOUT is kept greater than VBAT, such as

when a wall adapter is present, the charge timer will not

be reset when the part is put in suspend. A 2μA pull-down

is internally applied to this pin to ensure it is low at power

up when the pin is not being driven externally.

TIMER (Pin 6): Timer Capacitor. Placing a capacitor, CTIMER,

to GND sets the timer period. The timer period is:

t TIMER (Hours)

=

CTIMER • RPROG • 3Hours

0.1μF • 100k

Charge time is increased if charge current is reduced

due to undervoltage current limit, load current, thermal

regulation and current limit selection (HPWR).

Shorting the TIMER pin to GND disables the battery charg-

ing functions.

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