BQ24193_15 Datasheet, PDF (19/49 Pages) Texas Instruments – bq24193 I2C Controlled 4.5-A Single Cell USB/Adapter Charger with Narrow VDC Power Path Management and USB OTG

bq24193
www.ti.com
SLUSBG7 – DECEMBER 2014
8.3.3.4 Thermistor Qualification
The bq24193 continuously monitors battery temperature and applies JEITA profile with TS1/TS2 shorted. It
measures 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.
8.3.3.4.1 JEITA Guideline Compliance
To improve the safety of charging Li-ion batteries, JEITA guideline was released on April 20, 2007. The guideline
emphasized the importance of avoiding a high charge current and high charge voltage at certain low and high
temperature ranges.
To initiate a charge cycle, the voltage on TS pin must be within the V_T1 to V_T5 thresholds. If TS voltage exceeds
the T1–T5 range, the controller suspends charging and waits until the battery temperature is within the T1 to T5
range. At cool temperature (T1–T2), JEITA recommends the charge current to be reduced to at least half of the
charge current or lower. At warm temperature (T3–T5), JEITA recommends charge voltage less than 4.1 V.
The bq24193 provides flexibility voltage/current settings beyond the JEITA requirement. The voltage setting at
warm temperature (T3–T5) can be 4.2 V or 4.05 V (REG07 bit[4]). The current setting at cool temperature
(T1–T2) can be further reduced to 20% of fast charge current (REG05 bit[0]).
Charging Current
1I_CHG
4.2V
0.5I_CHG
0.2I_CHG
ISET=1
ISET=0
4.10V
4.05V
T1 T2
0⁰C 10⁰C
T3 T5
45⁰C
60⁰C
The resistor bias network has been updated as below.
RT2 =
V_VREF
´ RTH_COLD
´ RTH_HOT
´
æ
çè
1_-
VT1
1
VT5
ö
÷ø
RTH_HOT
´
æ
çè
V_VREF
VT5
-
ö
1_÷ø
-
RTH_COLD
´
æ
çè
V_VREF
VT1
-
ö
1_÷ø
Charging Voltage
VSET=1
T1 T2
0⁰C 10⁰C
VSET=0
T3
45⁰C
T5
60⁰C
V_{VREF - 1}
RT1 =
VT1
1₊ 1
RT2 RTH_COLD
(2)
Select 0°C to 60°C range for Li-ion or Li-polymer battery,
RTH_T1 = 27.28 kΩ
RTH_T5 = 3.02 kΩ
RT1 = 2.27 kΩ
RT2 = 6.86 kΩ
8.3.3.5 Charging Termination
The bq24193 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.
Copyright © 2014, Texas Instruments Incorporated
Product Folder Links: bq24193
Submit Documentation Feedback
19