LTC4065L/
LTC4065LX/LTC4065L-4.1
PIN FUNCTIONS
GND (Pin 1, Exposed Pad Pin 7):
Ground. The Exposed
Pad must be soldered to the PCB ground to provide both
electrical contact and rated thermal performance.
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 cur-
rent to the battery and regulates the final float voltage (4.2V
for LTC4065L/LTC4065LX and 4.1V for LTC4065L-4.1).
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 pro-
vides 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 volt-
age, the LTC4065L enters shutdown mode, dropping I
BAT
to about 1μA.
EN
(Pin 5):
Enable Input Pin. Pulling this pin above the
manual shutdown threshold (V
MS
is typically 0.82V) puts
the LTC4065L in shutdown mode. In shutdown mode, the
LTC4065L 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.
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
BAT
=
V
PROG
• 205
R
PROG
Floating the PROG pin sets the charge current to zero.
4065lfb
7
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
