How to convert Electrical Conductivity to pH

I have some data from measuring EC in solutions and I want to convert it to pH . Values of ADC of EC that I collect from microcontroller are 80 ( for EC : 0.2mS/cm ) , 90 ( for EC : 0.5mS/cm), 110 ( for EC 0.7mS/cm) .

pH and electrical conductivity are not the same. For example, a highly conductive solution can have either a high or low pH.