74HC138管脚图:74LS138 为3 线－8 线译码器，共有 54/74S138和 54/74LS138 两种线路结构型式，其工作原理如下：

当一个选通端（G1）为高电平，另两个选通端（/(G2A)和/(G2B)）为

低电平时，可将地址端（A、B、C）的二进制编码在一个对应的输出端以低

-74HC138 pin diagram: 74LS138-8 line, 3-wire decoder, the the total 54/74S138 and 54/74LS138 two line structure type, its working principle is as follows:

　　 When a strobe terminal (G1) is high, the other two selected through the end of (/ (G2A,)/(G2B))

Low, the output of the binary encoding of the address side (A, B, C) in a corresponding side with low