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| BQ24085_17 Datasheet, PDF (15/42 Pages) Texas Instruments – 750-mA Single-Chip Li-Ion and Li-Pol Charge Management IC With Thermal Regulation | |||
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www.ti.com
bq24085, bq24086, bq24087, bq24088
SLUS784E â DECEMBER 2007 â REVISED DECEMBER 2015
VIN
VCOLD(TS2)
0.6 x VIN
VHOT(TS1)
0.3 x VIN
Charge Suspend
Normal Temperature
Charge Range
Charge Suspend
Figure 11. Battery Temperature Qualification With NTC Thermistor
The external resistors RT1 and RT2 (see Figure 18) enable selecting a temperature window. If RTC and RTH are
the thermistor impedances for the Cold and Hot thresholds the values for RT1 and RT2 can be calculated as
follows for a NTC (negative temperature coefficient) thermistor. Solve for RT2 first and substitute into RT1
equation. RTC and RTH can be found in the NTC thermistor datasheet specification.
RT2
=
2.5 RTCRTH
RTC - 3.5RTH
(1)
[ ] RT1
=
3
7 RTHRT2
RTH + RT2
(2)
Applying a fixed voltage, 1/2 Vin (50% resistor divider from Vin to ground), to the TS pin to disable the
temperature sensing feature.
8.3.3 Input Overvoltage Detection, Power Good Status Output
The input power detection status for pin IN is shown at the open collector output pin PG.
Table 2. Input Power Detection Status
INPUT POWER DETECTION (IN)
NOT DETECTED
DETECTED, NO OVERVOLTAGE
DETECTED, OVERVOLTAGE
PG STATE
High impedance
LO
High impedance
The bq24085/6/7/8 detects an input overvoltage when V(IN) > V(OVP). When an overvoltage protection is detected
the charger function is turned off and the bq24085/6/7/8 is set to standby mode of operation. Since the OVP
detection is not latched, the IC returns to normal operation when fault condition is removed.
8.3.4 Charge Status Outputs
The open-collector STAT1 and STAT2 outputs indicate various charger operations as shown in Table 3. These
status pins can be used to drive LEDs or communicate to the host processor.
NOTE
OFF indicates the open-collector transistor is turned off. When termination is disabled
(TMR pin floating, or TE = Hi for bq24087) the Done state is not available; the status LEDs
indicate fast charge if V(BAT) > V(LOWV) and precharge if V(BAT) < V(LOWV). The available
output current is a function of the OUT pin voltage, See Figure 16.
Copyright © 2007â2015, Texas Instruments Incorporated
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Product Folder Links: bq24085 bq24086 bq24087 bq24088
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