参数资料
| 型号： | LTC4085EDE#TRPBF |
| 厂商： | Linear Technology |
| 文件页数： | 18/24页 |
| 文件大小： | 0K |
| 描述： | IC USB POWER MANAGER 14-DFN |
| 标准包装： | 2,500 |
| 功能： | 电源管理 |
| 电池化学： | 锂离子（Li-Ion） |
| 电源电压： | 4.35 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 14-WFDFN 裸露焊盘 |
| 供应商设备封装： | 14-DFN-EP（4x3） |
| 包装： | 带卷 (TR) |
LTC4085
OPERATION
For example, if the full charge current is programmed
to 500mA with a 100k PROG resistor the CHRG pin will
change state at a battery charge current of 50mA.
Note: The end-of-charge (EOC) comparator that moni-
tors the charge current latches its decision. Therefore,
the first time the charge current drops below 10% of the
programmed full charge current while in constant-voltage
mode will toggle CHRG to a high impedance state. If, for
some reason, the charge current rises back above the
threshold the CHRG pin will not resume the strong pull-
down state. The EOC latch can be reset by a recharge cycle
(i.e. V BAT drops below the recharge threshold) or toggling
the input power to the part.
Current Limit Undervoltage Lockout
An internal undervoltage lockout circuit monitors the
input voltage and disables the input current limit circuits
until V IN rises above the undervoltage lockout threshold.
The current limit UVLO circuit has a built-in hysteresis of
125mV. Furthermore, to protect against reverse current in
the power MOSFET, the current limit UVLO circuit disables
the current limit (i.e. forces the input power path to a high
impedance state) if V OUT exceeds V IN . If the current limit
UVLO comparator is tripped, the current limit circuits will
not come out of shutdown until V OUT falls 50mV below
the V IN voltage.
Charger Undervoltage Lockout
An internal undervoltage lockout circuit monitors the V OUT
voltage and disables the battery charger circuits until
V OUT rises above the undervoltage lockout threshold. The
battery charger UVLO circuit has a built-in hysteresis of
125mV. Furthermore, to protect against reverse current
in the power MOSFET, the charger UVLO circuit keeps the
Suspend
The LTC4085 can be put in suspend mode by forcing the
SUSP pin greater than 1V. In suspend mode the ideal diode
function from BAT to OUT is kept alive. If power is applied
to the OUT pin externally (i.e., a wall adapter is present)
then charging will be unaffected. Current drawn from the
IN pin is reduced to 50μA. Suspend mode is intended to
comply with the USB power specification mode of the
same name.
NTC Thermistor
The battery temperature is measured by placing a negative
temperature coefficient (NTC) thermistor close to the bat-
tery pack. The NTC circuitry is shown in Figure 4. To use
this feature, connect the NTC thermistor (R NTC ) between
the NTC pin and ground and a resistor (R NOM ) from the
NTC pin to V NTC . R NOM should be a 1% resistor with a
value equal to the value of the chosen NTC thermistor at
25°C (this value is 10k for a Vishay NTHS0603N02N1002J
thermistor). The LTC4085 goes into hold mode when the
resistance (R HOT ) of the NTC thermistor drops to 0.41
times the value of R NOM or approximately 4.1k, which
should be at 50°C. The hold mode freezes the timer and
stops the charge cycle until the thermistor indicates a
return to a valid temperature. As the temperature drops,
the resistance of the NTC thermistor rises. The LTC4085 is
designed to go into hold mode when the value of the NTC
thermistor increases to 2.82 times the value of R NOM . This
resistance is R COLD . For a Vishay NTHS0603N02N1002J
thermistor, this value is 28.2k which corresponds to ap-
proximately 0°C. The hot and cold comparators each have
approximately 3°C of hysteresis to prevent oscillation
about the trip point. Grounding the NTC pin can disable
the NTC function.
charger shut down if V BAT exceeds V OUT . If the charger
UVLO comparator is tripped, the charger circuits will not
come out of shut down until V OUT exceeds V BAT by 50mV.
4085fd
18
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