Datasheet

V
DRV
-1
V
COLD
RHI =
1 1
+
RLO RCOLD
1 1
V × RCOLD × RHOT × -
DRV
V V
COLD HOT
RLO =
V V
DRV DRV
RHOT × - 1 - RCOLD × -1
V V
HOT COLD
é ù
ê ú
ê ú
ë û
é ù é ù
ê ú ê ú
ê ú ê ú
ë û ë û
4.1V
T1
(0ºC)
T2
(10ºC)
T3
(45ºC)
T4
(50ºC)
T5
(60ºC)
4.15V
4.25V
0.5C
1.0C
Portion of spec not covered by TS
Implementation on bq2427x
bq24270
bq24271
www.ti.com SLUSB10 –JUNE 2012
Figure 6. Charge Current/Voltage During TS Conditions
To satisfy the JEITA requirements, four temperature thresholds are monitored; the cold battery threshold (T
NTC
<
0°C), the cool battery threshold (0°C < T
NTC
< 10°C) the warm battery threshold (45°C < T
NTC
< 60°C) and the
hot battery threshold (T
NTC
> 60°C). ). These temperatures correspond to the V
COLD
, V
COOL
, V
WARM
, and V
HOT
thresholds. Charging is suspended and timers are suspended when V
TS
< V
HOT
or V
TS
> V
COLD
. When V
HOT
<
V
TS
, V
WARM
the battery regulation voltage is reduced by 140 mV from the programmed regulation threshold.
When V
COOL
< V
TS
< V
COLD
, the charging current is reduced to half of the programmed charge current.
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 7. The resistor values are
calculated using the following equations:
(1)
(2)
Where:
V
COLD
= 0.6 x V
DRV
V
HOT
= 0.3 v V
DRV
Where RHOT is the NTC resistance at the hot temperature and RCOLD is the NTC resistance at cold
temperature.
For the bq24270 and bq24271, the WARM and COOL thresholds are not independently programmable. The
COOL and WARM NTC resistances for a selected resistor divider are calculated using the following equations:
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