Design of an isolated F/I converter

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.