Expansion circuit 1 of analog multi-way switch CD4051

CD4051 is a single-ended input 8-channel multiplexer. It has 3 channel
selection input terminals A, B, and C and an inhibit input terminal INH. The input
terminals A, B, and C signals are used to control the selection of one of the 8 channels. is connected. In
practical applications, if there are more than 8 channels of measured parameters, using a CD4051
multi-channel switch cannot meet the requirements for the number of channels. For this, multiple CD4051s can be
connected and expanded. Figure 27-6 shows the connection diagram of a 16-channel multiplexer composed of two CD
4051s. When the multi-way switch of chip 1 is turned on, all the multi-way switches of chip 2 are turned off; conversely, when
the multi-way switch of chip 2 is turned on, all the multi-way switches of chip 1 are turned off. Therefore, as long as one address (or data) line is used as the selection signal for the control end of chip 1 and chip 2, the channel selection input ends of the two chips share a set of address (or data) lines. By changing the state of the channel selection lines D3~DO, one of the 16 channels INO~IN15     can be selected . D3 is used to control the level of the INH input terminals of chip 1 and chip 2. When D3-0, the chip l is entered . Under this premise, the state of DZ-DO terminal changes, and only one of INO ~ IN7 can be selected. When D3-1, the inverter becomes low level, and chip 2 is selected. At this time, the status of the three lines D2--; DO can turn on the corresponding channels among IN8-IN15.