BQ24180 Datasheet, PDF (22/39 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and Accessory Power Connection

bq24180
SLUSA02 A – FEBRUARY 2010 – REVISED FEBRUARY 2010
1A
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400 mA
T1
(5ºC)
T2
(45ºC)
T3
(55ºC)
Figure 31. Charge Current During TS Conditions in Default Mode
When the bq24180 is not in default mode, the TS input is monitored and faults are displayed in the I²C registers.
If any of the 3 TS fault conditions occur, a single 128µs pulse is sent on the STAT and INT outputs and the
STATx and FAULT_x bits of the status registers are updated in the I²C. The FAULT_x bits signal a general
temperature fault. The TS_FAULTX bits in the NTC Monitor Register show the exact TS fault that has occurred.
I_NTC
bq24180
TS
+
V_COLD
+
V_HOT
TEMP
PACK +
PACK -
+ _VWARM
Figure 32. TS Circuit
Thermal Regulation and Protection
During the charging process, to prevent overheat of the chip, bq24180 monitors the junction temperature, T_J, of
the die and begins to taper down the charge current once T_J reaches the thermal regulation threshold, T_CF. The
charge current is reduced to zero when the junction temperature increases about 10°C above T_CF. At any state, if
T_J exceeds T_SHTDWN, bq24180 terminates charging and disables DCOUT in the I²C register. During thermal
shutdown mode, PWM is turned off, all timers are terminated and reset, and a single 128µs pulse is sent on the
STAT and INT outputs and the STATx and FAULT_x bits of the status registers are updated in the I²C. A new
charging cycle begins when T_J falls below T_SHTDWN by approximately 10°C. DCOUT must be enabled by the host
after a thermal shutdown fault.
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