LTC4069EDC Linear Technology, LTC4069EDC Datasheet - Page 10

• Manufacturer Part Number: LTC4069EDC
• Manufacturer: Linear Technology
• Type: Battery Chargerr

Specifications of LTC4069EDC

• Battery Type: Li-Ion
• Output Current: 500mA
• Output Voltage: 4.2V
• Operating Supply Voltage (min): 3.75V
• Operating Supply Voltage (max): 5.5V
• Operating Temp Range: -40C to 85C
• Package Type: DFN
• Mounting: Surface Mount
• Pin Count: 6
• Operating Temperature Classification: Industrial
• Lead Free Status / Rohs Status: Not Compliant

LTC4069
OPERATION
Regardless of mode, the voltage at the PROG pin is
proportional to the current delivered to the battery.
Battery Temperature Monitoring via NTC
The battery temperature is measured by placing a negative
temperature coeffi cient (NTC) thermistor close to the
battery pack. The NTC circuitry is shown in Figure 3.
To use this feature, connect the NTC thermistor, R
between the NTC pin and ground and a resistor, R
the NTC pin to V
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
value of the NTC thermistor drops to 0.53 times the value
of R
10
NOM
, which corresponds to approximately 40°C,
POWER
CC
ON
. R
NOM
1/4 CHARGE CYCLE
(1.125 HOURS)
should be a 1% resistor with a
1/10 FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
IS V
NO CHARGE CURRENT
CHRG PULSES (2Hz)
V
TRICKLE CHARGE MODE
CC
BAT
DEFECTIVE BATTERY
BAD BATTERY MODE
< 3V
< 2.9V?
V
YES
Figure 2. State Diagram of LTC4069 Operation
BAT
TEMPERATURE
≤ 2.9V
TEMPERATURE NOT OK
NOT OK
NOM
NO
, from
1/2 CHARGE CYCLE
NTC
CHARGE CYCLE
(2.25 HOURS)
BATTERY CHARGING SUSPENDED
CHRG PULSES (2Hz)
(4.5 HOURS)
IF V
V
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
IS V
FULL CHARGE CURRENT
CHRG STRONG PULL-DOWN
CC
,
CC
BAT
> V
FAST CHARGE MODE
RECHARGE MODE
> 3.6V AND
BAT
< 4.1V?
and when the value of the NTC thermistor increases to
3.26 times the value of R
approximately 0°C. Hold mode freezes the timer and stops
the charge cycle until the thermistor indicates a return to
a valid temperature. For a Vishay NTHS0603N01N1003J
thermistor, this value is 32.6k which corresponds to
approximately 0°C. The hot and cold comparators each
have approximately 3°C of hysteresis to prevent oscillation
about the trip point.
When the charger is in Hold mode (battery temperature is
either too hot or too cold) the CHRG pin pulses in a 2Hz,
25% duty cycle frequency unless the charge task is fi nished
or the battery is assumed to be defective. If the NTC pin
is grounded, the NTC function will be disabled
RECHARGE
NTC FAULT
+ 80mV?
UVLO
TEMPERATURE OK
2.9V < V
YES
YES
BAT
< 4.1V
NO
NO
CHRG HIGH IMPEDANCE
NO CHARGE CURRENT
CHRG HIGH IMPEDANCE
STANDBY MODE
UVLO MODE
NOM
, which corresponds to
V
BAT
> 4.1V
4069 F02
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