LTM8061_15 Datasheet, PDF (7/22 Pages) Linear Technology – 32V, 2A Module Li-Ion/ Polymer Battery Charger

LTM8061
Pin Functions
GND (Bank 1): Power and Signal Ground Return.
BAT (Bank 2): Battery Charge Current Output Bus. The
charge function operates to achieve the final float voltage
at this pin. The auto-restart feature initiates a new charge
cycle when the voltage at the BAT pin falls 2.5% below
the float voltage. Once the charge cycle is terminated, the
input bias current of the BAT pin is reduced to minimize
battery discharge while the charger remains connected.
In most applications, connect BIAS to BAT.
V_INA (Bank 3): Anode of Input Reverse Protection Schottky
Diode. Connect the input power here if input voltage pro-
tection is desired.
V_INC/CLP (Bank 4): This pad bank connects to the cathode
of the input reverse protection diode. In addition, system
current levels can be monitored by connecting a sense
resistor from this pin to the V_IN pin. Additional system
load is drawn from the V_IN pin connection, and maximum
system load is achieved when V_VINC/CLP – V_VIN = 50mV. The
LTM8061 servos the charge current required to maintain
programmed maximum system current. If this function is
not desired, connect the V_INC/CLP pin to the V_IN pin (see
the Applications Information section). Do not raise this
pin above V_IN + 0.5V.
V_IN (Bank 5): Charger Input Supply. Apply C_IN here. Con-
nect the input power here if no input power rectification
is required.
BIAS (Pin G7): The BIAS pin connects to the internal power
bus. Connect to a power source greater than 2.5V and
less than 10V. In most applications, connect BIAS to BAT.
CHRG (Pin K7): Open-Collector Charger Status Output.
Typically pulled up through a resistor to a reference volt-
age. This status pin can be pulled up to voltages as high
as V_IN and can sink currents up to 10mA. During a battery
charge cycle, CHRG is pulled low. When the charge cycle
terminates, the CHRG pin becomes high impedance. If the
internal timer is used for termination, the pin stays low
during the charge cycle until the charge current drops below
a C/10 rate even though the charger will continue to top
off the battery until the end-of-charge timer terminates the
charge cycle. A temperature fault also causes this pin to
be pulled low (see the Applications Information section). If
RUN is low, or the LTM8061 is otherwise powered down,
the state of the CHRG pin is invalid.
NTC (Pin H6): Battery Temperature Monitor Pin. This pin
is the input to the NTC (negative temperature coefficient)
thermistor temperature monitoring circuit. This function is
enabled by connecting a 10kΩ, β = 3380 NTC thermistor
from the NTC pin to ground. The pin sources 50μA, and
monitors the voltage across the 10kΩ thermistor. When
the voltage on this pin is above 1.36V (T < 0°C) or below
0.29V (T > 40°C), charging is disabled and the CHRG and
FAULT pins are both pulled low. If internal timer termina-
tion is being used, the timer is paused, suspending the
charge cycle. Charging resumes when the voltage on NTC
returns to within the 0.29V to 1.36V active region. There
is approximately 5°C of temperature hysteresis associated
with each of the temperature thresholds. The temperature
monitoring function remains enabled while thermistor
resistance to ground is less than 250kΩ. If this function
is not desired, leave the NTC pin unconnected.
For more information www.linear.com/LTM8601
8061fa
7