LTC1732-4 LINER [Linear Technology], LTC1732-4 Datasheet - Page 5

• Manufacturer Part Number: LTC1732-4
• Description: Lithium-Ion Linear Battery Charger Controller
• Manufacturer: LINER [Linear Technology]

PIN
BAT (Pin 1): Battery Sense Input. A bypass capacitor of
10 F or more is required to keep the loop stable when the
battery is not connected. A precision internal resistor
divider on this pin sets the final float potential. The resistor
divider is disconnected in sleep mode to reduce the
current drain on the battery.
SEL (Pin 2): 4.1V/4.2V Battery Selection Input Pin. Ground-
ing this pin will set the output float voltage to 4.1V per cell,
while connecting to V
For the LTC1732-4.2, the SEL pin must be connected to
V
CHRG (Pin 3): Open-Drain Charge Status Output. 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 for more than 15ms,
the N-channel MOSFET turns off and a 35 A current
source is connected from the CHRG pin to GND. When the
timer runs out or the input supply is removed, the current
source will be disconnected and the CHRG pin is forced
into a high impedance state.
TIMER (Pin 4): Timer Capacitor and Constant-Voltage
Mode Disable Input Pin. The timer period is set by placing
a capacitor, C
(hours) = (C
is connected to V
voltage mode is disabled and the chip will operate in
constant-current mode only. Shorting the TIMER pin to
GND will disable the internal timer function and the C/10
function.
CC
U
.
FUNCTIONS
U
TIMER
TIMER
CC
• 3 hours)/(0.1 F). When the TIMER pin
, to GND. The timer period is t
, the timer is disabled, the constant-
CC
U
will set the voltage to 4.2V per cell.
TIMER
GND (Pin 5): Ground.
PROG (Pin 6): Charge Current Program and Shutdown
Input Pin. The charge current is programmed by connect-
ing a resistor, R
= (V
into shutdown by floating the PROG pin and allowing the
internal 2.5 A current source to pull the pin above the
2.457V shutdown threshold voltage.
DRV (Pin 7): Drive Output Pin for the P-Channel MOSFET
or PNP Transistor. If a PNP pass transistor is used, select
a high beta transistor to minimize the charge current error
due to the base current.
V
within 54mV of V
mode, dropping I
Bypass this pin with a 1 F capacitor.
SENSE (Pin 9): Current Sense Input. A sense resistor,
R
This resistor is chosen using the following equation:
ACPR (Pin 10): Wall Adapter Present Output. When the
input voltage (wall adapter) greater than the undervoltage
lockout threshold is applied to the LTC1732, this pin is
pulled to ground by an internal N-channel MOSFET that is
capable of sinking 5mA to drive an external LED.
CC
SENSE
R
PROG
(Pin 8): Positive Input Supply Voltage. When V
SENSE
, must be connected from V
• 800 )/(R
= (V
LTC1732-4/LTC1732-4.2
PROG
PROG
CC
CC
to 7 A. V
• 800 )/(R
PROG
to ground. The charge current is I
, the LTC1732 is forced into sleep
• R
SENSE
CC
PROG
ranges from 4.5V to 12V.
). The IC can be forced
CC
• I
to the SENSE pin.
BAT
)
BAT
5
BAT
is