Specifications

TC35 / TC37 Hardware Interface Description
TC35_37_HD_02_V03.10 - Released Page 27 of 92 21.12.2001
3.2.2.2 Supported charging technique
Charging can be accomplished only in a temperature range from 0°C to +45°C. The
charging process supports trickle charging and processor controlled fast charging. In trickle
mode, the battery is charged at a rate of less than 10mA. The fast charging rate provided by
the charger or any other external source must be limited to 500mA. See also Table 29.
The charge cycle begins once the charger is tied to the two POWER pins of the ZIF
connector. First, the charging process goes into trickle charge mode, no matter whether the
battery was deeply or partially discharged. When the battery voltage reaches 3.2V within
60 minutes +10%, the Power ASIC turns on and wakes up the baseband processor.
Once activated, the baseband processor enables fast charging, in parallel to trickle charging.
Fast charging delivers a constant current until the battery voltage reaches 4.2V and then
proceeds with varying charge pulses. As shown in Figure 6, the pulse duty cycle is reduced
to adjust the charging procedure and prevent the voltage from overshooting beyond 4.2V.
Once the pulse width reaches the minimum of 100ms and the duty cycle does not change for
2 minutes, fast charging is completed.
4.3
4.2
3.8
Voltage
3.4
3.0
Constant current
t
OFF
= 100 ms
t
ON
= 100 ms
Time
100ms 2 ... 0.1s
100ms 0.1 ... 2s
Figure 6: Charging process
Note: Do not connect the charger to the VBATT+ lines. Only the POWER lines are
intended as input for charging!
The battery manufacturer must guarantee that the battery complies with the
described charging technique. Please refer to the application notes "Battery Pack"
and "Charging the Battery Pack" for a detailed description of the charging
characteristics.