I have a 2ch A/D Converter with A freescale MCU. It communicates with the PC through FT232R. All of this is isolated with ADUM5000 and ADUM4160. (It´s a USB bus-powered A/D converter)
All works fine, but I´m afraid of the Viso in the ADUM5000...
The signal for measure is 0-5V. With a Rail to Rail Operational Amplifier I can manage the buffer for the Analog Signals, so I can put after de buffer a resistive voltage divider, in the way that the MCU sees [0-4]V in each channel.
My fear is the Vcc provide to the buffer (Gain=1), so if I receive a signal of 5V my buffer must follow it with 5V.
I have 3 prototypes running OK. Just because the ADUM5000 provides [5.03 - 5.11] and never goes down 5V.
In one board I have a LED connected to the MCU, it seems the ADUM5000 reduce the Viso a little (5.03V)
In the other two boards Viso=5.11V (without LED)
Should I expect that Viso will be always the same? If Viso goes down from 4.95 there will be a little problem
In the datasheet says that Viso can vary from (4,7V - 5,3V) But I cannot find any more information about how and when this voltage could change.
If once running the ADUM5000 shows Viso=5,03V will this value change through the time or temperature??
Or simply will I receive some chips with differents Viso from the market? <-- that would be neat!
Information about this will be much appreciated.