Thanks for the response. We're using the ADR3425 for REFIN. Please see the attached image. Just a note about the schematic: the AAFx components are hierarchical blocks containing a programmable filter circuit.
Here is the answer I got "We only have a spice model for the ADR3425 (the 2.5V output version of this family). It is used as an exampleof behavior. Other voltages behave similarly." The spice models are available at:
Hello Suresha NS
You did a really good job and I learned a lot from your accuracy analysis document.
I made some comments in the attached document for your reference.
With best regards,
Why do you say the reference input draws high peak currents? I didn't see that in the d.s. and it's
a sigma-delta, not a SAR??
The eval board uses an ADR421, so that or an ADR43x should be fine. I like the 43x family
because you can…
I would not even consider the TL431 with a 16 bit ADC; you are just throwing money away.
The TL431 is a commodity reference, with 50 ppm/C tempco. So after your temperature
changes by 10 degrees, you have less than a 14 bit system. There is a noise…
Fig 19 is for the REF195, which is similar to the REF192. If you look at fig. 20 in the d.s.,
the pass element is a PNP, so Vce(sat) is probably less than 0.3V, so you should not have
any problem. However, why use the REF192, which is more than…
What are the red and blue traces? Which 623?? top or bottom?
Everything has a tempco. If you want very stable operation, you need to use resistors that are 5-10ppm/C tempco,
and get rid of the junk op amp, LM2904. Do not use a dual. You did…
I meant to add a cap, say 1uF-100uF across the lower resistor. This will give you low impedance at
higher frequencies. If you use 1k/1k, you have an RC lowpass from the 5V supply, so millivolts of noise
gets filtered. The cap doesn't do…
I need around 15-20mA stable 5.000V reference for powering A1301, a ratiometric hall sensor. Since the project has low budget, I choose ADR3450 and plan to increase output capability with something similar that shown in datasheet: