下拉电阻

微处理器管脚用下拉电阻R1与地相连，阻抗典型为几百千欧，在管脚上呈现出高阻状态。

The microcontroller 's pin connects to ground using pulldown resistor R1 with resistance , typically , of a few hundred kilohms to impress the high-impedance state on the pin .

如将其值的一半接到5V电源做上拉电阻，将另外的一半拉接到地做下拉电阻，则各个节点的两边偏置电阻最大总共为685Ω。

Placing half of this value as a pullup to5V and half as a pulldown to ground gives a maximum bias resistor value of685 Ω for each of the two biasing resistors .

文章介绍了一种用在高精度A／D转换器中的CMOS电压参考源，依靠PMOS管阈值电压差来产生电流，在外接下拉电阻上产生电压参考源。

In this paper , it introduces one kind of CMOS voltage reference source in high precision A / D converter , which produces current depending on difference of PMOS threshold voltage , and gives birth to voltage reference source on external get-down resistance .