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 74LS49数据手册
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·74XX49简介：
高电平有效，集电极开路。灭灯输入，有灯光强度调节功能。输出最大电压5.5V,吸收电流8mA。
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| 74XX49 BCD—七段译码驱动器功能表 |
十进数
或功能 | 输入 | 输出 | 备注
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| D C B A | BI | a | b | c | d | e | f | g |
| 0 | 0 0 0 0 | H | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 |
| 1 | 0 0 0 1 | H | 0 | 1 | 1 | 0 | 0 | 0 | 0 |
| 2 | 0 0 1 0 | H | 1 | 1 | 0 | 1 | 1 | 0 | 1 |
| 3 | 0 0 1 1 | H | 1 | 1 | 1 | 1 | 0 | 0 | 1 |
| 4 | 0 1 0 0 | H | 0 | 1 | 1 | 0 | 0 | 1 | 1 |
| 5 | 0 1 0 1 | H | 1 | 0 | 1 | 1 | 0 | 1 | 1 |
| 6 | 0 1 1 0 | H | 0 | 0 | 1 | 1 | 1 | 1 | 1 |
| 7 | 0 1 1 1 | H | 1 | 1 | 1 | 0 | 0 | 0 | 0 |
| 8 | 1 0 0 0 | H | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| 9 | 1 0 0 1 | H | 1 | 1 | 1 | 0 | 0 | 1 | 1 |
| 10 | 1 0 1 0 | H | 0 | 0 | 0 | 1 | 1 | 0 | 1 |
| 11 | 1 0 1 1 | H | 0 | 0 | 1 | 1 | 0 | 0 | 1 |
| 12 | 1 1 0 0 | H | 0 | 1 | 0 | 0 | 0 | 1 | 1 |
| 13 | 1 1 0 1 | H | 1 | 0 | 0 | 1 | 0 | 1 | 1 |
| 14 | 1 1 1 0 | H | 0 | 0 | 0 | 1 | 1 | 1 | 1 |
| 15 | 1 1 1 1 | H | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| BI | x x x x | L | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 |
[1].要求0—15时，灭灯输入（BI）必须开路或保持高电平。
[2].将一低电平直接输入BI端，则不管其他输入为何电平，所有的输出端均输出为低电平。
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