Hello,
I have an issue implementing a single supply 4-20mA receiver using the rcv420 chip. My design is based off the Application Bulletin of Single Supply 4-20mA Current Loop Receiver (http://www.ti.com/lit/an/sboa023/sboa023.pdf) and the rcv420 datasheet (http://www.ti.com/lit/ds/symlink/rcv420.pdf). My circuit is built according to figure 12 of the rcv420 datasheet, a 4-20mA to 5-0V conversion. The problem I am having occurs at around 16mA (or 1.25V output). From 4mA - 16 mA input, the output produces the correct voltage output range of 5V to 1.25V. But it saturates at 1.25V beyond 16mA, anything from 16mA to 20mA will only give me 1.25V output, but in theory 20mA should give me 0V output right? Does anyone know why this problem is occurring?
Thanks,
Michael