Datasheet

LTC4062
7
4062fb
UU
U
PI FU CTIO S
BAT (Pin 1): Charge Current Output. This pin provides
charge current to the battery and regulates the final float
voltage to 4.2V.
IN
+
(Pin 2): Positive Input of the Micropower Comparator.
The negative input is tied internally to a precise bandgap
voltage reference of 1V. There is approximately 50mV of
hysteresis associated with the input comparator threshold
(rising edge).
TIMER (Pin 3): Timer Program and Termination Select
Pin. This pin selects which method is used to terminate the
charge cycle. Connecting a capacitor, C
TIMER
, to ground
selects charge time termination. The charge time is set by
the following formula:
TIME HOURS HOURS
C
F
or
CF
TIME HOURS
HOURS
TIMER
TIMER
()()•
.
.•
()
()
=
µ
=µ
3
01
01
3
Connecting the TIMER pin to ground selects charge cur-
rent termination, while connecting the pin to V
CC
selects
user termination. See Applications Information for more
information on current and user termination.
OUT (Pin 4): Low Power Comparator Open-Drain Output.
This comparator output pin has two states; pull-down and
high impedance. This output can be used as a logic
interface or as an LED driver. In the pull-down state, an
NMOS transistor capable of sinking 10mA pulls down on
the OUT pin. The state of this pin is dependent on the value
of IN
+
. When IN
+
is greater than 1V the output pin is in pull-
down state, if IN
+
is less than 1V the output pin is in high
impedance state. See Applications Information.
CHRG (Pin 5): Open-Drain Charge Status Output. The
charge status indicator pin has three states: pull-down,
pulse at 6Hz and high impedance. This output can be used
as a logic interface or as a LED driver. In the pull-down
state, an NMOS transistor capable of sinking 10mA pulls
down on the CHRG pin. The state of this pin depends on the
value of I
DETECT
as well as the termination method being
used. See Applications Information.
C/5 (Pin 6): C/5 Enable Input. Used to control the amount
of current drawn by the charger when powered from a USB
port. A logic high on the C/5 pin sets the current limit to
100% of the current programmed by the PROG pin. A logic
low on the C/5 pin sets the current limit to 20% of the current
programmed by the PROG pin. An internal 3MΩ pull-down
resistor defaults the C/5 pin to its low current state.
EN (Pin 7): Charger Enable Input. A logic high on the EN
pin places the charger into shutdown mode, where the
input quiescent current is less than 50µA. A logic low on
this pin enables charging. An internal 3MΩ pull-down
resistor to ground defaults the charger to its enabled state.
I
DET
(Pin 8): Current Detection Threshold Program Pin.
The current detection threshold, I
DETECT
, is set by con-
necting a resistor, R
DETECT
, to ground. I
DETECT
is set by the
following formula:
I
R
R
I
V
R
or
R
V
I
DETECT
PROG
DET
CHG
DET
DET
DETECT
==
=
10
100
100
•
The CHRG pin becomes high impedance when the charge
current drops below I
DETECT
. I
DETECT
can be set to 1/10th
the programmed charge current by connecting I
DET
di-
rectly to PROG. If the I
DET
pin is not connected, the CHRG
output remains in its pull-down state until the charge time
elapses and terminates the charge cycle. See Applications
Information.
This pin is clamped to approximately 2.4V. Driving this pin
to voltages beyond the clamp voltage should be avoided.
PROG (Pin 9): Charge Current Program and Charge Cur-
rent Monitor. The charge current is set by connecting a
resistor, R
PROG
, to ground. When charging in constant
current mode, this pin servos to 1V. The voltage on this pin
can be used to measure the charge current using the
following formula:
I
V
R
BAT
PROG
PROG
=•1000