Linear Technology LTM8062EV Demo Board, 32V, 2A µModule Li-Ion Battery Charger with MPPT DC1621A DC1621A Data Sheet

Product codes

DC1621A

LTM8062/LTM8062A

8062fd

For more information

www.linear.com/LTM8062

pin FuncTions

GND (Bank 1, Pin L7): 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 charging

cycle when the voltage at the ADJ 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.
V

INA

(Bank 3): Anode of input reverse protection Schottky

diode. Connect the input power here if input reverse volt-

age protection is desired.
V

(Bank 4): Charger Input Supply. Decouple with at least

4.7µF to GND. Connect the input power here if no input

reverse voltage protection is needed.
BIAS (Pin G7): The BIAS pin connects to the internal

power bus. In most cases connect to V

BAT

. If this is not

desirable, connect to a power source greater than 2.8V

and less than 10V.
CHRG (Pin K7): Open-Collector Charger Status Output;

typically pulled up through a resistor to a reference

voltage. This status pin can be pulled up to voltages as

high as V

and can sink currents up to 10mA. During

a battery charging cycle, CHRG is pulled low. When the

charge current falls below C/10, the CHRG pin becomes

high impedance. If the internal timer is used for termina-

tion, the pin stays low during the charging cycle until the

charge current drops below a C/10 rate, approximately

200mA, 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).
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, B = 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 the internal timer termination is

being used, the timer is paused, suspending the charging

cycle. Charging resumes when the voltage on NTC returns

to within the 0.29V to 1.36V active region. There is approxi-

mately 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.
ADJ (Pin H7): Battery Float Voltage Feedback Input. The

charge function operates to achieve a final float voltage of

3.3V on this pin. The output battery float voltage (V

BAT(FLT)

)

is programmed using a resistor divider. V

BAT(FLT)

can be

programmed up to 14.4V. The auto-restart feature initi-

ates a new charging cycle when the voltage at the ADJ

pin falls 2.5% below the float voltage reference. The ADJ

pin input bias current is 110nA. Using a resistor divider

with an equivalent input resistance at the ADJ pin of 250k

compensates for input bias current error. Required resistor

values to program desired V

BAT(FLT)

follow the equations:

BAT(FLT)

• 2.5 • 10

3.3

(

Ω)

R1• 2.5 • 10

−(2.5 • 10

)

(

Ω)

R1 is connected from BAT to ADJ, and R2 is connected

from ADJ to ground.
FAULT (Pin J7): Open-Collector Fault Status Output; typi-

cally pulled up through a resistor to a reference voltage.

This status pin can be pulled up to voltages as high as

and can sink currents up to 10mA. This pin indicates

charge cycle fault conditions during a battery charging

cycle. A temperature fault causes this pin to be pulled

low. If the internal timer is used for termination, a bad bat-

tery fault also causes this pin to be pulled low. If no fault

conditions exist, the FAULT pin remains high impedance

(see the Applications Information section).
TMR (Pin J6): End-Of-Cycle Timer Programming Pin.

If a timer-based charge termination is desired, connect

a capacitor from this pin to ground. Full charge end-of

cycle time (in hours) is programmed with this capacitor

following the equation:
t

EOC

= C

TIMER

• 4.4 • 10

A bad battery fault is generated if the battery does not

reach the precondition threshold voltage within one-eighth

of t

EOC

, or:

PRE

= C

TIMER

• 5.5 • 10