BQ24262_15 Datasheet, PDF (25/56 Pages) Texas Instruments – bq2426x 3-A, 30-V, Host-Controlled Single-Input, Single-Cell Switched-Mode Li-Ion Battery Charger With Power-Path Management and USB-OTG Support

Not Recommended for New Designs : bq24260, bq24261
www.ti.com
bq24260, bq24261, bq24261M, bq24262
SLUSBU4D – DECEMBER 2013 – REVISED APRIL 2015
Device Functional Modes (continued)
where
• V_COLD = 0.60 × V_DRV
• V_HOT = 0.30 × V_DRV
(2)
RCOOL =
RLO ´ RHI´ 0.564
RLO - RLO ´ 0.564 - RHI´ 0.564
(3)
RWARM
=
RLO
RLO ´ RHI´ 0.383
- RLO ´ 0.383 - RHI´ 0.383
where
• RHOT is the NTC resistance at the hot temperature
• RCOLD is the NTC resistance at cold temperature
(4)
The WARM and COOL thresholds are not independently programmable. The COOL and WARM NTC
resistances for a selected resistor divider are calculated using Equation 3 and Equation 4.
V_{BATREG 1 x Charge/}
DISABLE – 140 mV 0.5 x Charge
V_DRV
bq2426x
TS COLD
+
TS COOL
+
TS WARM ₊
TS HOT
+
V_DRV
RHI
TS
PACK+
TEMP
RLO
PACK–
Figure 14. TS Circuit
9.4.17 Thermal Regulation and Protection
During the charging process, to prevent overheating in the chip, bq24260/1/1M/2 monitors the junction
temperature, T_J, of the die and reduces the input current once T_J reaches the thermal regulation threshold, T_REG.
The input current is reduced to zero when the junction temperature increases about 10°C above T_REG. Once the
input current is reduced to 0, the system current is reduced while the battery supplements the load to supply the
system. When the input current is completely reduced to 0 and T_J > 125°C, this is may cause a thermal
shutdown of the bq24260/1/1M/2 if the die temperature rises too high. At any state, if T_J exceeds T_SHTDWN,
bq24260/1/1M/2 stops charging and disables the buck converter. During thermal shutdown mode, PWM is turned
off, all timers are suspended, a single 128-μs 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 charge cycle resumes when T_J falls below
T_SHTDWN by approximately 10°C.
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