BQ24298_15 Datasheet, PDF (22/51 Pages) Texas Instruments – bq24298 I2C Controlled 3A Single Cell USB Charger With Narrow VDC Power Path Management and Adjustable Voltage USB OTG

bq24298
SLUSC59 – APRIL 2015
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VREF
V _BCOLDx
( -10ºC / 20ºC)
Temperature Range to
Boost
Boost Disable
Boost Enable
V _BHOTx
(55ºC / 60ºC / 65ºC)
Boost Disable
AGND
Figure 17. TS Pin Thermistor Sense Thresholds in Boost Mode
Assuming a 103AT NTC thermistor is used on the battery pack Figure 16, the value RT1 and RT2 can be
determined by using the following equation:
RT2 =
V_VREF
´ RTH_COLD
´ RTH_HOT
´
æ
ç
è
1
V_LTF
-
1
V_TCO
ö
÷
ø
RTH_HOT
´
æ
ç
V_VREF
è ^VTCO
-
ö
1_÷
ø
-
RTH_COLD
´
æ
ç
è
V_VREF
V_LTF
-
ö
1_÷
ø
V_{VREF - 1}
RT1 =
V_LTF
1₊ 1
RT2 RTH_COLD
(1)
Select 0°C to 45°C range for Li-ion or Li-polymer battery,
RTH_COLD = 27.28 kΩ
RTH_HOT = 4.911 kΩ
RT1 = 5.25 kΩ
RT2 = 31.23 kΩ
8.3.3.4 Charging Termination
The device terminates a charge cycle when the battery voltage is above recharge threshold, and the current is
below termination current. After the charging cycle is complete, the BATFET turns off. The converter keeps
running to power the system, and BATFET can turn back on to engage supplement mode.
When termination occurs, the status register REG08[5:4] is 11, and an INT is asserted to the host. Termination is
temporarily disabled if the charger device is in input current/voltage regulation or thermal regulation. Termination
can be disabled by writing 0 to REG05[7].
8.3.3.4.1 Termination When REG02[0] = 1
When REG02[0] is HIGH to reduce the charging current by 80%, the charging current could be less than the
termination current. The charger device termination function should be disabled. When the battery is charged to
fully capacity, the host disables charging through CE pin or REG01[5:4].
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