一种隔离式频率电流转换器的设计

Design of an isolated F/I converter

提出一种隔离式频率电流转换器的设计方案。该频率电流转换器采用PIC16F1823单片机采集200～1 000Hz频率信号,通过SPI协议与DA芯片MCP4911通信,将频率信号转换成电压信号,然后通过集成电路AD694将电压信号线性转换为标准的4～20mA电流信号。工业测试结果表明,该频率电流转换器的数据采集精度可达0.5级,误差范围小于±0.5%,满量程工作时电流为26.8±0.2mA,最低功耗仅为450mW。

The paper proposed design scheme of an isolated F/I converter. The converter uses PIC16F1823 single chip microcomputer to collect frequency signal of 200 ～ 1 000 Hz and transmits the frequency signal through SPI protocol to MCP4911 DA conversion chip for F/V conversion, then IC AD694 converts the voltage signal into standard current signal of 4～20 mA. The industrial testing result showed that the precision of data collection of the converter achieves 0.5 level, error range is less than ±0.5%, working current is 26.8±0.2 mA in full range, and the lowest power consumption is 450 nW.