M668 dimming control ASIC

VDl~VD4 and vs form the main circuit of the electric lamp H, and the control circuit is composed of M668 and so on. VD5, Rl and Cl
form a resistor step-down voltage stabilizing circuit, which outputs a DC voltage of about 6V for powering the integrated block. The LED is a weak light indicator, making it easy
to find the switch position at night. If low light indication is not required, short wires can be used to connect the two solder joints of the LED. R2 and R3
form a voltage divider to provide synchronization signals for pin 5 of the integrated block. C3 is the integrated block
the gate of the thyristor VS to control the conduction angle of VS, thus achieving four-speed brightness control. R7 and R8 are safety resistors to ensure
the safety of the user. When a human hand touches the electrode sheet M once, the clutter signal induced by the human body is added to the input
terminal SEN of A through R7 and R8. After being processed by the internal circuit, pin 7 outputs a series of pulse signals and is sent to the gate of vs through C3. Extremely, to control the conduction angle of vs
, so that the brightness of the bulb is low light - medium light -. From brightest to off...the four gears change cyclically. At maximum brightness, the vs conduction
angle is 1500. If pin 4 is not connected to ground but connected to pin 8, the circuit becomes a simple touch light switch
without dimming function.