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BQ25120_15 Datasheet, PDF (24/68 Pages) Texas Instruments – bq25120 700-nA Low IQ Highly Integrated Battery Charge Management Solution for Wearables and IoT
BQ25120
SLUSBZ9A – AUGUST 2015 – REVISED AUGUST 2015
VBATREG 1 x Charge/
DISABLE – 140 mV 0.5 x Charge
VDRV
www.ti.com
bq25120
TS COLD
+
TS COOL +
TS WARM +
TS HOT
+
VDRV
RHI
TS
PACK+
TEMP
RLO
PACK–
Figure 15. TS Circuit
æ1
1ö
R(LO)
=
VIN x R(COLD) x R(HOT)
R(HOT)
x
æ
ççè
VIN
V(HOT)
ö
- 1÷÷ø
-
x ççè V(COLD) - V(HOT) ÷÷ø
R(COLD)
x
æ
ççè
VIN
V(COLD)
ö
- 1÷÷ø
(1)
R(HI)
=
æ
ççè
VIN
V(COLD)
ö
- 1÷÷ø
æ
ççè
1
R(LO)
+
1
R(COLD)
ö
÷÷ø
(2)
Where
• R(HOT) = the NTC resistance at the hot temperature
• R(COLD) = the NTC resistance at the cold temperature
The warm and cool thresholds are not independently programmable. The cool and warm NTC resistances for a
selected resistor devider are calculated using Equation 3 and Equation 4.
R(COOL)
=
R(LO)
-
R(LO) x R(HI)
R(LO) x 0.57
x 0.57
- R(HI)
x
0.57
(3)
( ) R(WARM)
=
R(LO)
x R(HI)
R(LO)
x 0.38
-
R(LO) x 0.38 - R(HI) x 0.38
(4)
24
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