Datasheet

VREF
TS
RT2
RT1
RTH
103AT
bq24610/7
VREF
LTF
COLD
V
1
V
RT1 =
1 1
+
RT2 R TH
-
æ ö
´ ´ ´ -
ç ÷
è ø
æ ö
æ ö
´ - - ´ -
ç ÷
ç ÷
è ø
è ø
VREF COLD HOT
LTF TCO
VREF VREF
HOT COLD
TCO LTF
1 1
V RTH RTH
V V
RT2 =
V V
RTH 1 RTH 1
V V
CHARGE SUSPENDED CHARGE SUSPENDED
TEMPERATURE RANGE
TO INITIATE CHARGE
TEMPERATURE RANGE
DURING A CHARGE
CYCLE
V
LTF
GND
V
TCO
GND
V
LTF_HYS
VREF
VREF
CHARGE SUSPENDED CHARGE SUSPENDED
V
HTF
V
LTF
V
LTF_HYS
bq24610
bq24617
SLUS892B –DECEMBER 2009–REVISED SEPTEMBER 2013 www.ti.com
Temperature Qualification
The controller continuously monitors battery temperature by measuring the voltage between the TS pin and
GND. A negative temperature coefficient thermistor (NTC) and an external voltage divider typically develop this
voltage. The controller compares this voltage against its internal thresholds to determine if charging is allowed.
To initiate a charge cycle, the battery temperature must be within the V
LTF
to V
HTF
thresholds. If battery
temperature is outside of this range, the controller suspends charge and the safety timer, and waits until the
battery temperature is within the V
LTF
to V
HTF
range. During the charge cycle, the battery temperature must be
within the V
LTF
to V
TCO
thresholds. If battery temperature is outside of this range, the controller suspends charge
and waits until the battery temperature is within the V
LTF
to V
HTF
range. The controller suspends charge by
turning off the PWM charge FETs. Figure 17 summarizes the operation.
Figure 17. TS Pin, Thermistor Sense Thresholds
Assuming a 103AT NTC thermistor on the battery pack as shown in Figure 1, the value RT1 and RT2 can be
determined by using the following equations:
(8)
(9)
Figure 18. TS Resistor Network
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