Is there a LTSpice model for the AD7495 or at least a LTSpice model for the Vin? I am using the 2.5V RefOut with a resistor voltage divider for the Vin pin and I am seeing less than 1/2 of the reference. I do not see a spec for the input impedance of the

I am sampling the ADC at 1Mhz, I have a 30K resistor from the RefOut pin to another 30K resistor to gnd. On the center tap between these resistors I have a 1K resistor into the Vin pin. I am seeing 1.084V on the Vin pin. When I remove the 1K resistor (isolating the Vin pin from being in parallel with the lower 30K resistor) the divider is correct  at 1.25V.

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  • Daryl, Thanks for the reply.  After my post, I started some empirical testing which shows about 112 ohms of input impedance for our application. The seems to be closely aligned with Analog Input section of the datasheet which states this resistor is typically about 100 ohms for R1 (Figure 14). I will assume that there is no LTSpice model available for the AD7495.

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  • Daryl, Thanks for the reply.  After my post, I started some empirical testing which shows about 112 ohms of input impedance for our application. The seems to be closely aligned with Analog Input section of the datasheet which states this resistor is typically about 100 ohms for R1 (Figure 14). I will assume that there is no LTSpice model available for the AD7495.

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