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WM_PRJ_Q2686_PTS_001-010
June 30, 2009
Q2686 Wireless CPU
®
3.13
Battery Charging Interface
The Q2686 Wireless CPU
®
supports one battery charging circuit, two
algorithms and one hardware charging mode (pre-charging) for 3 battery
technologies:
•
Ni-Cd (Nickel-Cadmium) with algorithm 0
•
Ni-Mh (Nickel-Métal Hydrure) with algorithm 0
•
Li-Ion
(Lithium-Ion) with the embedded PCM (Protection Circuit
Module).algorithm 1
The two algorithms control a switch, which connects the CHG-IN signal to the
VBATT signal. The algorithm controls the frequency and the connected time of
the switching. During the charging procedure, battery charging level is
monitored and when Li-Ion algorithm is used, battery temperature is monitored
via the ADC1/BAT-TEMP input.
One more charging procedure is provided by the Q2686 Wireless CPU
®
. This is
called “Pre-charging” mode, but is a special charging mode because it is
activated only when the Wireless CPU
®
is OFF. Control is in this case only
performed by the hardware. The purpose of this charging mode is to avoid
battery damage by preventing the battery from being discharged to below the
minimum battery level.
3.13.1
Ni-Cd / Ni-Mh Charging Algorithm
To charge the battery, the algorithm measures battery level when the switch is
open (T2) and charges the battery by closing the switch (T3). When the battery
is charged (battery voltage has reached BattLevelMax) the switch is open for
time T3.
BattLevelMax
T1
T2
T3
Battery Level
Switch State
opened
closed
Figure 7: Ni-Cd / Ni-Mh charging waveform
Electrical characteristics of Ni-Cd / Ni-Mh battery timing charge
Parameter
Min
Typ
Max
Unit
T1
1
s
T2
0.1
s
T3
5
s
Note: T1,T2,T3 and BattLevelMax may be configured by AT command.
