BQ24190_15 Datasheet, PDF (20/52 Pages) Texas Instruments – bq2419x I2C Controlled 4.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG

bq24190, bq24192, bq24192I
SLUSAW5B – JANUARY 2012 – REVISED DECEMBER 2014
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9.3.3.4 Thermistor Qualification
The high capacity battery usually has two or more single cells in parallel. The bq24190, bq24192, bq24192I
provides two TS pins to monitor the thermistor (NTC) in each cell independently.
9.3.3.4.1 Cold/Hot Temperature Window
The bq24190, bq24192, bq24192I continuously monitors battery temperature by measuring the voltage between
the TS pins and ground, typically determined by a negative temperature coefficient thermistor and an external
voltage divider. The device compares this voltage against its internal thresholds to determine if charging is
allowed. To initiate a charge cycle, the battery temperature must be within the V_LTF to V_HTF thresholds. During the
charge cycle the battery temperature must be within the V_LTF to V_TCO thresholds, else the device suspends
charging and waits until the battery temperature is within the V_LTF to V_HTF range.
REGN
bq2419x
TS
RT1
RT2
RTH
103AT
Figure 15. TS Resistor Network
When the TS fault occurs, the fault register REG09[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
V_LTF
TEMPERATURE RANGE TO
INITIATE CHARGE
CHARGE SUSPENDED
TEMPERATURE RANGE
DURING A CHARGE CYCLE
CHARGE SUSPENDED
VREF
V_LTF
V_LTFH
V_LTFH
CHARGE at full C
CHARGE at full C
V_HTF
AGND
CHARGE SUSPENDED
CHARGE SUSPENDED
Figure 16. TS Pin Thermistor Sense Thresholds
V_TCO
AGND
Assuming a 103AT NTC thermistor is used on the battery pack, the value RT1 and RT2 can be determined by
using the following equations:
20
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