Datasheet

RLO 0.383 RHI
RW ARM =
RLO RLO 0.383 RHI 0.383
´ ´
- ´ - ´
RLO 0.564 RHI
RCOOL =
RLO RLO 0.564 RHI 0.564
´ ´
- ´ - ´
DRV
COL D
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
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bq24165
bq24166
bq24167
SLUSAP4B –DECEMBER 2011–REVISED MARCH 2013 www.ti.com
EXTERNAL NTC MONITORING (TS, bq24166/7)
The bq24166 and bq24167 provide 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.
For the bq24166, two temperature thresholds are monitored; the cold battery threshold (T
NTC
< 0°C) and the hot
battery threshold (T
NTC
> 60°C). These temperatures correspond to the V
COLD
and V
HOT
thresholds. Charging is
suspended and timers are suspended when V
TS
< V
HOT
or V
TS
> V
COLD
.
To satisfy the JEITA requirements, the bq24167 monitors four temperature thresholds; the cold battery threshold
(T
NTC
< 0°C), the cool battery threshold (0°C < TNTC < 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. As with the bq24166, 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 140mV 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 24. The resistor values are
calculated using the following equations:
(3)
(4)
Where:
V
COLD
= 0.60 × V
DRV
V
HOT
= 0.30 × V
DRV
Where RHOT is the NTC resistance at the hot temperature and RCOLD is the NTC resistance at cold
temperature.
For the bq24167, 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:
(5)
(6)
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