BQ25895_16 Datasheet, PDF (24/67 Pages) Texas Instruments – Adjustable Voltage 3.1-A Boost Operation

bq25895
SLUSC88A – MARCH 2015 – REVISED MAY 2016
REGN
bq25895
TS
RT1
RT2
RTH
103AT
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Figure 14. TS Resistor Network
When the TS fault occurs, the fault register REG0C[2:0] indicates the actual condition on each TS pin and an INT
is asserted to the host. The STAT pin indicates the fault when charging is suspended.
VREF
TEMPERATURE RANGE TO
INITIATE CHARGE
TEMPERATURE RANGE
DURING A CHARGE CYCLE
VREF
CHARGE SUSPENDED
V_LTF
CHARGE SUSPENDED
V_LTF
V_LTFH
V_LTFH
CHARGE at full C
CHARGE at full C
V_HTF
AGND
CHARGE SUSPENDED
CHARGE SUSPENDED
Figure 15. TS Pin Thermistor Sense Thresholds
V_TCO
AGND
Assuming a 103AT NTC thermistor on the battery pack as shown in Figure 14, the value RT1 and RT2 can be
determined by using Equation 2:
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
(2)
Select 0°C to 45°C range for Li-ion or Li-polymer battery,
RTH_COLD = 27.28 kΩ
RTH_HOT = 4.91 kΩ
RT1 = 5.21 kΩ
RT2 = 29.87 kΩ
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