Hi, we want to use the OPA354 as DC Line-Driver/(Gain +1) for a 0 to 4V Signal to generate a 0-4V Output Signal to Drive a 75Ohm cable with 75Ohm end-Termination. Supply Voltage 0V // 5V .
I understand that the 4V will not be achived to 100% as the OPAMP has to "work" against the 75Ohm Termination to GND.
But what will happen für the 0V especiallly für Slow Signals with 0V for 100us or more. Will 0V be achieved by the OPAMP or does I have to expect some Offset (how much)
Best regards
Dietmar
Dietmar,
In fact OPA354 will be able to swing all the way to 4V with a 0-5V supply.
I am assuming by 75 ohm cable you mean characteristic impedance of the cable and not actual resistance. In that case, only the 75 ohm termination to GND is the load. A 4V output swing means OPA354 needs to provide 53.33 mA which is well within its capability. Hence you will be able to get close to 4V at Vout.
OPA354 can typically swing to 0.1V from GND and at least to within 0.3V from GND.
The key specs you are interested in from the datasheet are below:
Also, if you are interested in swing to GND, you can refer to below TI reference design. It discusses how you can get swing all the way to GND but it does require availability of a negative voltage source in your application.
Thanks,
Keyur
