LTC4069 Просмотр технического описания (PDF) - Linear Technology

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производитель

LTC4069

Standalone 750mA Li-Ion Battery Charger in 2 × 2 DFN with NTC Thermistor Input

Linear Technology 

LTC4069

Operation

POWER

ON

UVLO

NO

IF VCC > 3.6V AND

VCC > VBAT + 80mV?

TEMPERATURE

NOT OK

YES

NTC FAULT

BATTERY CHARGING SUSPENDED

CHRG PULSES (2Hz)

TEMPERATURE NOT OK

VBAT ≤ 2.9V

TEMPERATURE OK

2.9V < VBAT < 4.1V

TRICKLE CHARGE MODE

1/10 FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

FAST CHARGE MODE

FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

1/4 CHARGE CYCLE

NO CHARGE CYCLE

NO

(1.125 HOURS)

(4.5 HOURS)

DEFECTIVE BATTERY

IS VBAT < 2.9V?

RECHARGE

IS VBAT < 4.1V?

UVLO MODE

CHRG HIGH IMPEDANCE

VBAT > 4.1V

STANDBY MODE

NO CHARGE CURRENT

CHRG HIGH IMPEDANCE

YES

YES

BAD BATTERY MODE

NO CHARGE CURRENT

CHRG PULSES (2Hz)

VCC < 3V

RECHARGE MODE

FULL CHARGE CURRENT

CHRG STRONG PULL-DOWN

1/2 CHARGE CYCLE

(2.25 HOURS)

4069 F02

Figure 2. State Diagram of LTC4069 Operation

In typical operation, the charge cycle begins in con-

stant-current mode with the current delivered to the battery

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

LTC4069 results in the junction temperature approaching

115°C, the amplifier (TA) will begin decreasing the charge

current to limit the die temperature to approximately 115°C.

As the battery voltage rises, the LTC4069 either returns to

constant-current mode or enters constant-voltage mode

straight from constant-temperature mode.

Regardless of mode, the voltage at the PROG pin is pro-

portional to the current delivered to the battery.

Battery Temperature Monitoring via NTC

The battery temperature is measured by placing a negative

temperature coefficient (NTC) thermistor close to the

battery pack. The NTC circuitry is shown in Figure 3.

To use this feature, connect the NTC thermistor, RNTC, be-

tween the NTC pin and ground and a resistor, RNOM, from

the NTC pin to VCC. RNOM should be a 1% resistor with a

value equal to the value of the chosen NTC thermistor at

25°C (this value is 100k for a Vishay NTHS0603N01N1003J

thermistor). The LTC4069 goes into hold mode when the

4069fc

10

For more information www.linear.com/LTC4069

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