LTC4075 datasheet(7/16 Pages) LINER

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LTC4075/LTC4075X

4075Xfa

USBIN (Pin 1): USB Input Supply Pin. Provides power to

the battery charger. The maximum supply current is 650mA.

This pin should be bypassed with a 1µF capacitor.

IUSB (Pin 2): Charge Current Program for USB Power.

The charge current is set by connecting a resistor, RIUSB,

to ground. When charging in constant-current mode, this

pin servos to 1V. The voltage on this pin can be used to

measure the battery current delivered from the USB input

using the following formula:

BAT

IUSB

•1000

ITERM (Pin 3): Termination Current Threshold Program.

The termination current threshold, ITERMINATE, is set by

connecting a resistor, RITERM, to ground. ITERMINATE is set

by the following formula:

TERMINATE

ITERM

100

When the battery current, IBAT, falls below the termination

threshold, charging stops and the

⎯C⎯H⎯R⎯G output becomes

high impedance.

This pin is internally clamped to approximately 1.5V. Driving

this pin to voltages beyond the clamp voltage can draw

large currents and should be avoided.

⎯P⎯W⎯R (Pin 4): Open-Drain Power Supply Status Output.

When the DCIN or USBIN pin voltage is sufﬁcient to begin

charging (i.e. when the supply is greater than the under-

voltage lockout threshold and at least 180mV above the

battery terminal), the

⎯P⎯W⎯R pin is pulled low by an internal

N-channel MOSFET. Otherwise

⎯P⎯W⎯R is high impedance.

This output is capable of sinking up to 10mA, making it

suitable for driving an LED.

⎯C⎯H⎯R⎯G (Pin 5): Open-Drain Charge Status Output. When

the LTC4075 is charging, the

⎯C⎯H⎯R⎯G pin is pulled low by

an internal N-channel MOSFET. When the charge cycle is

completed,

⎯C⎯H⎯R⎯G becomes high impedance. This output

is capable of sinking up to 10mA, making it suitable for

driving an LED.

ENABLE (Pin 6): Enable Input. When the LTC4075 is

charging from the DCIN source, a logic low on this pin

enables the charger. When the LTC4075 is charging from

the USBIN source, a logic high on this pin enables the

charger. If this input is left ﬂoating, an internal 2M

pulldown resistor defaults the LTC4075 to charge when

a wall adapter is applied and to shut down if only the USB

source is applied.

USBPWR (Pin 7): Open-Drain USB Power Status Output.

When the voltage on the USBIN pin is sufﬁcient to begin

charging and there is insufﬁcient power at DCIN, the USB-

PWR pin is high impedance. In all other cases, this pin is

pulled low by an internal N-channel MOSFET, provided that

there is power present at the DCIN, USBIN, or BAT inputs.

This output is capable of sinking up to 1mA, making it

suitable for driving high impedance logic inputs.

IDC (Pin 8): Charge Current Program for Wall Adapter

Power. The charge current is set by connecting a resis-

tor, RIDC, to ground. When charging in constant-current

mode, this pin servos to 1V. The voltage on this pin can

be used to measure the battery current delivered from the

DC input using the following formula:

BAT

IDC

•1000

BAT (Pin 9): Charger Output and Regulator Input. This pin

provides charge current to the battery and regulates the

ﬁnal ﬂoat voltage to 4.2V.

DCIN (Pin 10): Wall Adapter Input Supply Pin. Provides

power to the battery charger. The maximum supply

current is 950mA. This should be bypassed with a 1

μF

capacitor.

Exposed Pad (Pin 11): GND. The exposed backside of the

package is ground and must be soldered to PC board ground

for electrical connection and maximum heat transfer.

PI FU CTIO S

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