converting rs-232 voltage to current in my circuit design
converting rs-232 voltage to current in my circuit design
(OP)
Im using a TI Transimpedance Amplifier OPA138 in a design. The amp is used to convert input current to voltage output.
For reasons related to quick testing capabilities I want to take rs232 voltage signals (from my laptop) and input these signals into the amp. But the amp like I said before is looking for current (10mA max).
So my question is since the serial signal is voltage based can i just place a series resistor between the rs232 signal source and my amp to provide the current that the am is looking for?
I calculated 5k resistor foe 2ma current input. I measured 10V serial voltage.
For reasons related to quick testing capabilities I want to take rs232 voltage signals (from my laptop) and input these signals into the amp. But the amp like I said before is looking for current (10mA max).
So my question is since the serial signal is voltage based can i just place a series resistor between the rs232 signal source and my amp to provide the current that the am is looking for?
I calculated 5k resistor foe 2ma current input. I measured 10V serial voltage.





RE: converting rs-232 voltage to current in my circuit design
If you are only looking at a PC's sorta- pseudo- RS232 output, it may swing 0 to 5 volts or 0 to `12 volts depending on how it was mis-engineered and by whom.
To sort of half answer your question, a series resistor as you have proposed should limit the current going through your current transducer.
Mike Halloran
Pembroke Pines, FL, USA
RE: converting rs-232 voltage to current in my circuit design
RE: converting rs-232 voltage to current in my circuit design