LTC4065LEDC datasheet(12/16 Pages) LINEAR

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LTC4065/LTC4065A

4065fb

Transconductance amplifier, TA, limits the die tempera-

ture to approximately 115

°C when in constant-tempera-

ture mode. Diode D3 ensures that TA does not affect the

charge current when the die temperature is below approxi-

mately 115

°C. The PROG pin voltage continues to give an

indication of the charge current.

In typical operation, the charge cycle begins in constant-

current mode with the current delivered to the battery

equal to 1000V/RPROG. If the power dissipation of the

LTC4065/LTC4065A results in the junction temperature

approaching 115

°C, the amplifier (TA) will begin decreas-

ing the charge current to limit the die temperature to

approximately 115

°C. As the battery voltage rises, the

LTC4065/LTC4065A either return to constant-current mode

or enter constant-voltage mode straight from constant-

temperature mode. Regardless of mode, the voltage at

the PROG pin is proportional to the current delivered to

the battery.

OPERATIO

IS EN > SHUTDOWN

THRESHOLD?

ENABLE

CHRG HIGH IMPEDANCE

SHUTDOWN MODE

IF VCC > 3.6V AND

VCC > VBAT + 80mV?

UVLO

UVLO MODE

1/10 FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

TRICKLE CHARGE MODE

FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

FAST CHARGE MODE

IS VBAT < 2.9V?

DEFECTIVE BATTERY

IS VBAT < 4.1V?

RECHARGE

NO CHARGE CURRENT

CHRG PULSES (2Hz)

BAD BATTERY MODE

FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

RECHARGE MODE

NO CHARGE CURRENT

CHRG HIGH IMPEDANCE

STANDBY MODE

CHRG HIGH IMPEDANCE

YES

4065 F02

VBAT ≤ 2.9V

1/4 CHARGE CYCLE

(1.125 HOURS)

VCC < 3V

EN > SHDN

THRESHOLD

CHARGE CYCLE

(4.5 HOURS)

1/2 CHARGE CYCLE

(2.25 HOURS)

2.9V < VBAT < 4.1V

VBAT > 4.1V

YES

POWER

Figure 2. State Diagram of LTC4065 Operation

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