HT7700 dimming control ASIC

The stepless dimming desk lamp made with HT7700 integrated circuit has two methods: key control and touch control:
the circuit using key control stepless dimming is shown in Figure 2-8. VDI, VD2, R2 and Cl form a resistor step-down rectifier circuit, which outputs about 9V DC working
voltage for integrated block A. When the power is first turned on, the lamp H is off. Press switch SB. If the pressing time is less
than 0.7s, the light will turn on. If you continue to press SB, the light brightness will decrease smoothly to 96 levels. Release SB and the light will maintain this
brightness. If you press the SB key for less than 0.7 seconds, the light will go out. The circuit of a stepless dimming lamp
using touch control is shown in Figure 2-9. It uses signals induced by the human body to trigger dimming
. M is the touch electrode sheet (the metal shell of the desk lamp can also be used), and the hand touch time is less than 0.7s. The light changes from off to on.
If you continue to touch, the brightness of the light will gradually decrease. After you let go, the brightness of the light will remain unchanged. CI is the isolation safety capacitor.