Hi there

I am having trouble finding I2C DIP ADC's with a resolution greater than 8 bits (I need 12bit - the customer is adament - despite the fact it is overkill)

Could I do something along the lines of the following with 2x 8Bit ADC's in the Philips PCF package?


Put an op amp 1 that works on anything lower than ½ of the range of 4-20mA (anything less than 12mA) then when the current goes over 12mA op amp 1 turns off and op amp 2 turns on, measuring 12.0000001mA (12mA + 1/255 of 8mA) – 20mA

Then each ADC would measure an 8mA span with 8bit resolution rather than a 16mA span with 8bit resolution. Giving 16bit resolution over the 16mA span

Any ideas on how I could do this on the anolog side would be appreciated, the digital side should be easy, I have the data nicely formatted into two bytes so all I have to do is add or subtract and offset and I have a useable value


Appreciate your thoughts

Marshall Brown