LTM8062

9

8062f

OPERATION

8062 F01

BATTERY VOLTAGE

BATTERY CHARGE

CURRENT

RUN

CHRG

FAULT

MAXIMUM CHARGE CURRENT

PRECONDITION CURRENT

C/10

0 AMPS

FLOAT VOLTAGE

RECHARGE THRESHOLD

PRECONDITION THRESHOLD

1

0

1

0

0

1

Figure 1. Typical C/10 Terminated Charge Cycle (TMR Grounded, Time Not to Scale)

Figure 2. Typical EOC (Timer-Based) Terminated Charge Cycle

(Capacitor Connected to TMR, Time Not to Scale)

8062 F02

BATTERY VOLTAGE

BATTERY CHARGE

CURRENT

RUN

CHRG

FAULT

MAXIMUM CHARGE CURRENT

PRECONDITION CURRENT

C/10 CURRENT

AUTOMATIC

RESTART

FLOAT VOLTAGE

RECHARGE THRESHOLD

PRECONDITION THRESHOLD

1

0

1

0

0

1

which termination scheme is used. When the timer-based

scheme is used, the LTM8062 also supports bad battery

detection, which triggers a system fault if a battery stays

in precondition mode for more than one-eighth of the total

programmed charge cycle time.

Once charging terminates and the LTM8062 is not actively

charging, the charger automatically enters a low current

standby mode in which supply bias currents are reduced

to 85μA. If the battery voltage drops 2.5% from the full

charge float voltage, the LTM8062 engages an automatic

charge cycle restart. The IC also automatically restarts a

new charge cycle after a bad-battery fault once the failed

battery is removed and replaced with another battery.

The LTM8062 contains a battery temperature monitoring

circuit. This feature, using a thermistor, monitors battery

temperature and will not allow charging to begin, or will

suspend charging, and signal a fault condition if the bat-

tery temperature is outside a safe charging range. The

LTM8062 contains two digital open-collector outputs,

CHRG and FAULT, which provide charger status and signal

fault conditions. These binary coded pins signal battery

charging, standby or shutdown modes, battery temperature

faults and bad battery faults. For reference, C/10 and TMR

based charging cycles are shown in Figures 1 and 2.