4-20 mA Converters
4-20 mA Converters
(OP)
Does anyone knows a single chip with the following characteristics:
Input: 4-20 mA as input from a field pressure/temperature
transmiter.
Output: 0.1-2.8 Vdc (0-5 Vdc)as input to ADC.
I knew a couple of option but they don´t satisfy me. One is using galvanic isolators that have this characteristics (weidmuller/Phoenix Contact) but they are too expensive.
The other is using an AD620+some resistor..to weak.
Thanks.
Input: 4-20 mA as input from a field pressure/temperature
transmiter.
Output: 0.1-2.8 Vdc (0-5 Vdc)as input to ADC.
I knew a couple of option but they don´t satisfy me. One is using galvanic isolators that have this characteristics (weidmuller/Phoenix Contact) but they are too expensive.
The other is using an AD620+some resistor..to weak.
Thanks.
RE: 4-20 mA Converters
RE: 4-20 mA Converters
Using 4..20 mA signal is a very good means to transmit a signal reliable over extended distance in industrial installations. So ner68 should continue to follow the approach he has choosen, unless the transmitter is really close (<1m) to the electronics.
RE: 4-20 mA Converters
RE: 4-20 mA Converters
As for pressure transducer We use some conventional from Fisher-Roasemount, so I bounded to them.
RE: 4-20 mA Converters
RE: 4-20 mA Converters
http://focus.ti.com/docs/prod/productfolder.jhtml?genericPartNumber=RCV420
Steve Smith
Product Engineer
Staco Energy Products Co.
www.stacoenergy.com
RE: 4-20 mA Converters
4-20ma has been used for longer distance purposes as you noted but from what I have seen it is a fading technology for such purpose. A good 6 wire ratio-metric amplifier can easily be used with cables of 10-40'. Some of our own signal conditioner boards are used with 100-200' cables with very good results. Our boards are 24 bit with <.25uV noise being typical. The trend lately though is to convert to a digital signal for transmitting long distances. Each time you run a signal through another converter you induce one more source of error. We do use 4-20ma for lower accuracy purposes when long cable lengths are needed but overall accuracy or resolution is not.