U2405B
| Model | U2405B |
| Description | Fast Charge Controller for Drained NiCd/NiMH Batteries |
| PDF file | Total 17 pages (File size: 313K) |
| Chip Manufacturer | TEMIC |
U2405B
Temperature Control, Figure 7
When the battery temperature is not inside the specified
temperature windows,
the overal temperature control will
not allow the charge process. Sensor short circuit or
interruption also leads to switch-off.
Differentiation is made whether the battery exceeds the
maximum allowable temperature, T
max
, during the
charge phase or the battery temperature is outside the
temperature window range before battery connection.
A permanent switch-off follows after a measurement
period of 20.48 s, if the temperature exceeds a specified
level, which is denoted by a status of a red LED
1
. A charge
sequence will start only when the specified window
temperature range is attained. In such a case, the green
LED
2
starts blinking immediately showing a quasi charge
readiness, even though there is no charge current flow.
NTC sensors are normally used to control the temperature
of the battery pack. If the resistance values of NTC are
known for maximum and minimum conditions of
allowable temperature, then other resistance values, R
T1
,
R
T2
and R
T3
are calculated as follows:
suppose R
T2
= 100 k
W
, then
R
T1
R
T3
+
R
+
R
NTCmax
V
Ref
– 4V
4V
R
T2
R
T1
NTCmin
V
Ref
R
T2
V
Ref
14
T
max
7
R
T1
R
T3
7V
+
–
High
temperature
V
Ref
= 4 V
Sensor
8
NTC
sensor
7V
94 8682
+
–
Low
temperature
Figure 7. Temperature window
TELEFUNKEN Semiconductors
Rev. A2, 14-Nov-96
9 (17)
