74LS138 為3 線-8線解碼器,共有 54LS138和 74LS138 兩種線路結構型式。54LS138為軍用,74LS138為民用。
基本介紹
- 中文名:3 線-8線解碼器
- 外文名:74LS138
- 作用:組合邏輯電路的設計
- 組成:TTL與非門組成
- 特徵:完全解碼器
- 輸入:三位或四位二進制
工作原理
![](/img/6/50d/f0d9043b511e49c050a5d227e2ba.jpg)
![](/img/e/b5c/275766ad4a777cf4b235dbc5914c.jpg)
引腳功能
![圖1 74LS138 圖1 74LS138](/img/1/69f/cGcq5CM5M2NmNDNkJGZ0MWNyQzMzAjMlNmYyM2LtVGdp9yYpB3LltWahJ2Lt92YuUHZpFmYuMmczdWbp9yL6MHc0RHa.jpg)
![](/img/8/f82/74af9230910f4106192c504b60fc.jpg)
![](/img/b/25e/f3f4291ac5b28fcb625aa70f0788.jpg)
![](/img/6/2d4/0e3b2860e88759059332d8d724fc.jpg)
![](/img/6/0e7/276760a88a4d91c9ab252234224e.jpg)
![](/img/0/a5e/d7f86876a25333a47a655ef0dbe8.jpg)
![](/img/e/de1/a275e50e02449f331b8f9960b72f.jpg)
內部邏輯圖
![圖2 內部邏輯圖 圖2 內部邏輯圖](/img/3/ed3/nBnauQmZkJWOzQDZzQmNzU2YiFjN1EjM5MGNwI2MzAjY5QzM0MDOyEmM1Q2LtVGdp9yYpB3LltWahJ2Lt92YuUHZpFmYuMmczdWbp9yL6MHc0RHa.jpg)
真值表
輸入 | 輸出 | ||||||||||||
G1 | /G2A | /G2B | A2 | A1 | A0 | /Y0 | /Y1 | /Y2 | /Y3 | /Y4 | /Y5 | /Y6 | /Y7 |
× | 1 | × | × | × | × | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
× | × | 1 | × | × | × | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
0 | × | × | × | × | × | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
1 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 |
1 | 0 | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 |
1 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 1 |
1 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 1 |
1 | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 |
1 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 |
1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 |