7

LTC4065/LTC4065A

4065fb

PI FU CTIO S

GND (Pin 1): Ground.

CHRG (Pin 2): Open-Drain Charge Status Output. The

charge status indicator pin has three states: pull-down,

pulse at 2Hz and high impedance state. This output can be

used as a logic interface or as an LED driver. When the

battery is being charged, the CHRG pin is pulled low by an

internal N-channel MOSFET. When the charge current

drops to 10% of the full-scale current, the CHRG pin is

forced to a high impedance state. If the battery voltage

remains below 2.9V for one quarter of the charge time, the

battery is considered defective and the CHRG pin pulses at

a frequency of 2Hz.

BAT (Pin 3): Charge Current Output. Provides charge

current to the battery and regulates the final float voltage

to 4.2V. An internal precision resistor divider on this pin

sets the float voltage and is disconnected in shutdown mode.

to 5.5V. This pin should be bypassed with at least a 1

µF

voltage, the LTC4065 enters shutdown mode, dropping

EN (Pin 5, LTC4065 Only): Enable Input Pin. Pulling this

cally 0.82V) puts the LTC4065 in shutdown mode. In

shutdown mode, the LTC4065 has less than 20

µA supply

current and less than 1

µA battery drain current. Enable is

the default state, but the pin should be tied to GND if unused.

ACPR (Pin 5, LTC4065A Only): Open-Drain Power Supply

the ACPR pin will be pulled down to ground; otherwise the

pin is high impedance.

PROG (Pin 6): Charge Current Program and Charge Cur-

ground programs the charge current. When charging in

constant-current mode, this pin servos to 1V. In all modes,

the voltage on this pin can be used to measure the charge

current using the following formula:

I

V

R

BAT

PROG

PROG

=

• 1000

Floating the PROG pin sets the charge current to zero

(LTC4065) or puts the part in shutdown mode (LTC4065A).

In shutdown mode, the LTC4065A has less than 20

µA

supply current and about 1

µA battery drain current.

Exposed Pad (Pin 7): Ground. The Exposed Pad must be

soldered to the PCB ground to provide both electrical con-

tact and rated thermal performance.