choosing 2.048 voltage reference?

[Sajjadkhan]

i have to connect a 2.048 voltage reference to an 12bit ADC MCP3204. i have come down to a result of 2 chips.
1. ADR380 $1.95
2. Ref191 (25PPM) $3.2
3. Ref191 (5PPM) $5.72

Here is the digikey filtered result:

https://www.digikey.com/scripts/dks...&ptm=0&fid=0&quantity=0&PV-5=23463&PV-5=21047

I have to use it in an environment of temperature like 10-45 degree C. and your circuit is as good as its reference, so please help me choose which one is best?

 

[barry]

How do you define "best"? Lowest price? Tolerance?

If you don't need 5ppm, than why pay for it? The adr380 has an initial tolerance of 0.24%==>5mV, this is actually better than the REF191(10mv) with the same temp coefficient.

 

[keith1200rs]

You don't say what accuracy you require but if cost is important, the LM4040 series tend to be reasonably priced.

Keith

 

[Sajjadkhan]

I would define best if the performance fits a certain scenario with the lowest cost. lets say as an example that i am making an accurate current meter which measure down to 1mA and up to (4096-1) mA by using mcp3204 12 bit adc. so i have calculated that for 25ppm ADR380, if temperature changes from 25 degree C to 50 Degree C and current is 1.500 Amps@ 25 degree, then after a 25 degree change my current display will still be 1.5009 amps. so i guess ADR380 would be ok.

 

[keith1200rs]

You need to look carefully at the curves rather than just using ppm values. Over such a limited temperature range you are working over what is usually the flattest part of the temperature curve. Also, I assume "initial accuracy" will be important to you.

Keith