BQ24230 Datasheet, PDF (23/33 Pages) Texas Instruments – USB-FRIENDLY LITHIUM-ION BATTERY CHARGER AND POWER-PATH MANAGEMENT IC

bq24230
bq24232
www.ti.com .......................................................................................................................................... SLUS821A – OCTOBER 2008 – REVISED DECEMBER 2008
The allowed temperature range for a 103AT-2 type thermistor is 0°C to 50°C. However, the user can increase
the range by adding two external resistors. See Figure 31 for the circuit. The values for RT1 and RT2 are
calculated using the following equations:
-1500μA ´ (RHOT + RCOLD) ± 20 ´ 5625μA ² ´ (RCOLD-RHOT)² + 105μW ´ (RCOLD - RHOT)
RT1 =
3000μA
(1)
RT2 =
1 V ´ (R1 + RHOT)
250 μA ´ RT1 + 250 μA ´ RHOT - 1 V
(2)
RHOT and RCOLD are the thermistor resistance at the desired hot and cold temperatures, respectively. Note
that the temperature window cannot be tightened more than using on the thermistor connected to TS, it can only
be extended.
bq2407x
I_NTC
TS
+
V_COLD
+ _VHOT
RT1
PACK+
TEMP
RT2
PACK-
Figure 31. Extended TS Temperature Thresholds
Copyright © 2008, Texas Instruments Incorporated
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