微机保护采样电路动态工作范围的实用扩展方法

A Practical Way to Expand Dynamic Working Scope of Sampling Circuit in Microcomputer Protection

结合目前采用 12位A/D的保护装置精度较低的实际情况 ,介绍了在 12位A/D芯片的前置放大电路中 ,采用精密模拟开关及精密电阻构成二进制程控放大器 ,并由CPU根据最近一组采样值的幅度确定程控放大器的档位 ,通过合理调整该程控放大器的增益 。

For the lower precision of protective device using 12?bit A/D converter,a binary programmed amplifier is introduced,which is made of a precise analog multiplexer and accurate resistors.Based on the latest group of sampling values,CPU decides the setting of the amplifier.The dynamic working scope of the sampling circuit in microcomputer protection is expanded by rationally adjusting the gain of the programmed amplifier.