7
LTC4065/LTC4065A
4065fb
UU
U
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.
V
CC
(Pin 4): Positive Input Supply Voltage. This pin
provides power to the charger. V
CC
can range from 3.75V
to 5.5V. This pin should be bypassed with at least a 1µF
capacitor. When V
CC
is within 32mV of the BAT pin
voltage, the LTC4065 enters shutdown mode, dropping
I
BAT
to about 1µA.
EN (Pin 5, LTC4065 Only): Enable Input Pin. Pulling this
pin above the manual shutdown threshold (V
MS
is typi-
cally 0.82V) puts the LTC4065 in shutdown mode. In
shutdown mode, the LTC4065 has less than 20µA supply
current and less than 1µA 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
Status Output. When V
CC
is greater than the undervoltage
lockout threshold (3.6V) and V
BAT
+ 80mV (if V
BAT
> 3.6V),
the ACPR pin will be pulled down to ground; otherwise the
pin is high impedance.
PROG (Pin 6): Charge Current Program and Charge Cur-
rent Monitor Pin. Connecting a 1% resistor, R
PROG
, to
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 20µA
supply current and about 1µA 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.
