Other Parts Discussed in Thread: ADC128S022
Hi,
I would like to ask you following questions about ADS128S022 input filter.
Q1) There is an explanation below at data sheet p16.
"The ADC128S022 will deliver best performance when driven by a low-impedance source (less than 100 Ω)."
Could you tell me the reason why the sorce shold be less than 100ohm?
I suppose it is due to "R1(=500ohm)" of "input circuit" which is shown at Figure 37, datasheet p16.
In case of using over 100ohm, the time constant of the sampling circuit is larger than "R1*C2" and it will happen the error of sampled analog data.
Is my understanding correct?
Q2) To use over 100ohm resigter..
If my idea is correct about Q1, I think it is possible to use over 100ohm by using large input capacitor.
For example, in case of using 30nF (=30pF(C2)*1000), the error of sampled analog input signal will be less than 0.1%, I think.
And in this case, I suppose we can use large register, for example, 5Kohm registor.
How is my idea?
Thank you for your support.
Best Regards,
Takumi
