Datasheet

LTC4063
7
4063fc
pin FuncTions
BAT (Pin 1): Charger Output and Regulator Input. This pin
provides charge current to the battery and regulates the
final float voltage to 4.2V. This pin also supplies power to
the LDO regulator.
OUT
(Pin 2): LDO Regulator Output. This pin should be
bypassed with a ≥2µF low ESR capacitor as close to the
pin as possible for best performance. The minimum V
OUT
is 1.2V.
FB (Pin
3): Regulator Feedback Input. The voltage on this
pin is compared to the internal reference voltage (800mV)
by the error amplifier to keep the output voltage in regula-
tion. An external resistor divider between OUT and FB sets
the output voltage.
LDOEN (Pin
4): LDO Enable Input. A logic high on the
LDOEN pin shuts down the LDO. In this state, OUT becomes
high impedance and the battery drain current drops to
less than 5µA. A logic low on the LDOEN pin enables the
LDO regulator. A 2M pull-down resistor defaults the LDO
to its enabled state.
CHGEN (Pin
5): Charger Enable Input. A logic high on the
CHGEN pin places the charger into shutdown mode, where
the I
CC
quiescent current is less than 65µA. A logic low on
this pin enables battery charging. A 2M pull-down resistor
to ground defaults the charger to its enabled state.
CHRG (Pin
6): Open-Drain Charge Status Output. The
charge status indicator pin has two states: pull-down
and high impedance. This output can be used as a logic
interface or an 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 is dependent on the
value of I
DETECT
as well as the termination method being
used. See Applications Information.
TI
MER (Pin 7): 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
µF
or
C µF
Ti
TIMER
TIMER
( ) •
.
. •
=
=
3
0 1
0 1
mme Hours
Hours
( )
( )3
Connecting the pin to ground selects Charge Current
termination, while connecting the pin to V
CC
selects User
termination. See Applications Information.
IDET (Pin
8): Current Detection Threshold Program Pin.
The current detection threshold, I
DETECT
, is set by con-
necting a resistor, R
DET
, 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
DE
= =
=
10
100
100
•
TTECT
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 IDET
directly
to PROG. See Applications Information.
This pin is clamped to approximately 2.4V. Driving this
pin to voltages beyond the clamp voltage can draw large
currents and 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
V
CC
(Pin 10): Positive Input Supply Pin. Provides power
to the battery charger. This pin should be bypassed with
a 1µF capacitor.
GND
(Exposed
Pad Pin 11): Ground. This pin is the back
of the Exposed Pad package and must be soldered to the
PCB copper for minimal thermal resistance.