Wireless Charging Sonic Electric Toothbrushes
WAS-1972EN V1.00
3 / 17
December 27, 2021
Functional Description
Solution Features
This solution consists of a charging base and a toothbrush body. Their characteristics will be
explained below.
Charging Base
Operating voltage: DC 5V – powered by a USB interface
Operating current: 160 mA – when connected to the toothbrush body
The charging base is powered by a 5V USB interface. LC resonance is implemented using a PWM
function to control the internal MOS transistors. An internal demodulation circuit together with an
external current-sampling resistor can implement communication demodulation. The ID returned by
the toothbrush body is used to determine whether the charging base is powered on.
Toothbrush Body
Operating voltage: DC 3.0V~4.2V – powered by a lithium battery
Operating current: Standby current consumption of 1µA (Sleep Mode), operating current
consumption of 600mA (LED + sonic motor)
Lithium battery charging management: The master BP45F1330 MCU includes an integrated
linear charging circuit which is used for lithium battery charging management. The H-bridge
drive circuit can directly drive the motor.
The toothbrush body is powered by an LC resonance circuit which is supplied to the MCU through a
regulator circuit. The internal linear charging circuit is used for 3.7 V lithium battery trickle charging,
constant current and constant voltage charging control. The charging current varies according to the
user design. During the charging process, the toothbrush body will communicate with the charging
base, which will obtain the toothbrush body ID.
Solution Functions
The application solution consists of a charging base and a toothbrush body. Figure 2 shows the
product hardware.
Sonic electric toothbrush
Button
Mode indicator
Charging indicator
Charging base
Figure 2. Product Hardware
