Datasheet

DRV
COLD
V
1
V
RHI
1 1
RLO RCOLD
-
=
+
DRV
COLD HOT
DRV DRV
HOT COLD
1 1
V RCOLD RHOT
V V
RLO
V V
RHOT 1 RCOLD 1
V V
é ù
´ ´ ´ -
ê ú
ë û
=
é ù é ù
´ - - ´ -
ê ú ê ú
ë û ë û
T1
(0 C)
o
T2
(10 C)
o
T3
(45 C)
o
T4
(50 C)
o
T4
(60 C)
o
1.0C
0.5C
4.25V
4.15V
4.1V
Portion of spec not covered by TS
Implementation on bq24272
bq24272
www.ti.com SLUSB09 –JUNE 2012
2. V
IN
< V
SLP
+ V
BAT
3. Thermal Shutdown
External NTC Monitoring (TS)
The I
2
C interface allows the user to easily implement the JEITA standard for systems where the battery pack
thermistor is monitored by the host. Additionally, the bq24272 provides a flexible, voltage based TS input for
monitoring the battery pack NTC thermistor. The voltage at TS is monitored to determine that the battery is at a
safe temperature during charging. The bq24272 enables the user to easily implement the JEITA. The JEITA
specification is shown in Figure 5.
Figure 5. Charge Current/Voltage During TS Conditions
The TS function is voltage based for maximum flexibility. Connect a resistor divider from DRV to GND with TS
connected to the center tap to set the threshold. The connections are shown in Figure 6. The resistor values are
calculated using the following equations:
(1)
(2)
Where:
V
COLD
= 0.60 × V
DRV
V
HOT
= 0.60 × V
DRV
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