Wireless Charging Sonic Electric Toothbrushes
WAS-1972EN V1.00
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December 27, 2021
Power input: After receiving the LC resonance energy signal transmitted by the charging base, the
toothbrush body will pass through a full-bridge rectifier circuit and a Zener regulator circuit, then
provide power to the BP45F1330 linear charging circuit.
Linear charger circuit: Select trickle/constant current/constant voltage charging modes by detecting
the battery voltage.
1.
Trickle charging mode: During this initial charging process, for a battery that has been in an
over-discharged state, when the battery voltage is less than 2.5V, the battery will be pre-charged
at a constant current of 4mA. If the battery voltage is greater than 2.5V, the battery will be
charged at 0.1 times a constant current charging current (I
BAT_CC
) set by the firmware, that is,
0.1×I
BAT_CC
.
2.
Constant current charging mode: During this second stage, when the battery voltage is greater
than 3V, the battery will be charged using a constant current charging current, which is
controlled by the firmware.
3.
Constant voltage charging mode: When the battery voltage is greater than 4.2V, it will be
charged using a constant voltage during this third stage. The charging current gradually
decreases as the constant voltage charging time increases. When the charging current is less than
0.1 times the constant current charging current, then the charging will cease.
Note: Here a 300mAh capacity lithium battery is taken as an example, 0.1C means charging at
30mA and 1C means charging at 300mA.
Modulation
During the charging process, the toothbrush will carry out one-way communication with the
charging base in the way of load change and transmits the ID code.
H-Bridge drive circuit
The integrated H-bridge drive circuit can control the sonic motor to rotate backward or forward.
Button
A button switch is used to switch the operating modes.
LEDs
Three white LEDs are used to display the operating modes and one RGB LED to display the
battery capacity.
