Suggestion on generating 4.096V for microcontroller A/D voltage reference

Hi guys, I would like to create a 4.096V reference voltage for my A/D circuit. Can someone suggest a circuit with the least components I can build? I am using PIC18F4620 but I think it doesn't have a FVRCON register. Any IC or simple circuit that could generate this voltage without messing up the analog signal?

Thanks.

You might try one of these.

crutschow said:

You might try one of these.

Click to expand...

I already did some searching before posting a thread here and saw MCP1541 but what confuses me is the Vin-Vss 7V because right inside the chart there's also 4.3V < Vin < 5.5V. Is 7V just the maximum input voltage? Can someone clarify this for me?

I was hoping for a suggestion from someone who tested a circuit already and contrasted it with another circuit and expecting some feedback or things he experienced building them. Thanks anyway Crutschow.

Check my analogue PIC tutorial, which uses an adjustable precision reference IC, which is easily available (and used in lots of TV's VCR's etc.)

You can also get fixed voltage ones.

lloydi12345 said:

I already did some searching before posting a thread here and saw MCP1541 but what confuses me is the Vin-Vss 7V because right inside the chart there's also 4.3V < Vin < 5.5V. Is 7V just the maximum input voltage? Can someone clarify this for me?

I was hoping for a suggestion from someone who tested a circuit already and contrasted it with another circuit and expecting some feedback or things he experienced building them. Thanks anyway Crutschow.

Click to expand...

The 4.3V-5.5V is normal operation (output guaranteed) while the 7V is absolute maximum input, any voltage higher than that will kill the device (or you will get unexplained operation).

The MCP1541 is a good part, with 50ppm/°C temperature response. I have used a similar part, the LM4040 4.096V reference, with 100ppm/°C temperature stability. For a little more money, you can get them down to 10ppm/°C. I have another product which uses an AD1583 ref (3.00V 0.1%, 50ppm/°C) which has a 12V max input. When I went to 15V on my power rail, I had to put a 3.3V zener in line with the Vin pin in order not to violate the 12V max rating input voltage.

Thanks! gonna try out the MCP1541