ADC0809 是8 位逐次逼近型A/D转换器。它由一个8路模拟开关、一个地址锁存译码器、一个A/D 转换器和一个三态输出锁存器组成（见图1）。多路开关可选通8个模拟通道，允许8 路模拟量分时输入，共用A/D 转换器进行转换。三态输出锁器用于锁存A/D 转换完的数字量，当OE 端为高电平时，才可以从三态输出锁存器取走转换完的数据。-ADC0809 8-bit successive approximation A/D converter. It consists of an 8-channel analog switch, an address latch decoder, an A/D converter and a three-state output latch (see Figure 1). Multi-switch selectable through eight analog channels, allowing time-8 analog inputs, common A/D converter to convert. Three-state output latch lock is used for A/D converting the digital value, when the OE terminal is high, it can be from the tri-state output latch removed converting the data.