Jeethu Rao wrote:
> Hi,
> A guy in here wants a couple of 0-10volts to 4-20ma convertors for
> Interfacing some sensors to a PLC. Are there any directly
> Applicable ICs for this or should I build it out of OPAMPS ?
>
> The only IC I could find was MAX1459, which is for resistive sensors.
> And its got a built in DAC for compensation etc. I'm looking for
> Something simpler.
>
> Thanks,
>
> Jeethu Rao

4-20mA units can work as passive or active.
How this unit will work?

Active is when it generates the 4-20mA current based on an internal 25V
generator, obviously the other loop side will act as passive and will only
reads the current.

Passive is when it uses a 25V power line to control 4-20mA current on the
loop - in this case, the 25V generator is located at the remote (reader) at
the loop.

Active is easier to produce since the power supply feeds both parts of the
unit, the 25V and the 0-10 to 4-20mA converter.  Passive units needs to be
well done produced since they will feed energy from the loop power, and
sometimes the loop power was also not so well done, so, passive units
should consume very low power and consume less than 4mA...

Wagner.

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads