How to use a TC301D chip to achieve human induction without costing less than ￥1.00

With the rapid development of Internet of things technology, the demand is more and more extensive. In addition to the common communication switch mode, most related electrical appliances are equipped with the switch mode of body sensing or touch. Recently, another customer asked for this kind of scheme, which requires the minimum cost to achieve the induction distance of 6-7cm. We chose TC301D chip, which is powered by 5v dc. After a lot of tests, we found that the effect is good and the stability is high. The following is our testing process, only for the reference of peers with such requirements.

Compared with external infrared induction or gravity induction, capacitive human body induction has the characteristics of fewer auxiliary devices, smaller volume and lower cost.

Chip connection modeThe TC301D chip scheme circuit is simple. When it is used for human body induction, only the 7 and 8 pins (FUN, VCC) are short-connected, and the 4 and 5 pins (CR, CX) are short-connected to remove the capacitance of the 4 pins. In this way, the chip has self-correction function, which can be corrected according to the environment, and no wrong action will occur due to the change of environment.

Capacitive induction design principle is that when the chip sensing the human body, will always have a signal output, when people leave the light will be off. The difficulty lies in how to control the induction distance and range of the ground lamp correctly. If the distance is too small, when the person standing above will not be able to sense, if the distance is too large, the induction will occur wrong action. Loop winding is a relatively simple and efficient way, of course, induction antenna can also be used other structures, such as large area of foil and so on.

The longitudinal sensing distance of the chip is 6-7 cm and the transverse sensing distance is 2-3 cm. The density and length of winding are not fixed. The higher the winding density, the farther the induction distance. It can be adjusted according to the actual situation.