Divider and lowpass combined

1. Not that I'm aware of, call it a filtered voltage divider :)

2. \$fc=\frac{(R_1+R_2)\sqrt{(10^{3/10}-1)}}{2\pi*R_1*R_2*C_1}\approx \frac{(R_1+R_2)}{2\pi*R_1*R_2*C_1} \$

3. \$R_1//R_2//C_1 \$

4. There are other considerations to take into account. In your case for instance, the conversion speed (the time it takes to charge the ADC's internal sampling capacitor) which would have an impact on the max series resistance, max Vin voltage and so on.

1) I call this a voltage divider with a filter cap. There's no special name for it as far as I know

2) \$f_c = \frac{1}{2\pi * (R_1//R_2) * C_1}\$

Where \$R_1//R_2\$ is the value you get when \$R_1\$ and \$R_2\$ are in parallel

3) can be answered by learning some basic network theory. This is explained in any textbook about electronics or electronic networks.

4) yes, by learning what is mentioned under 3)

The answers to 4) are:

\$R_1 = \frac{V_{in} R_{out}}{V_{out}}\$

\$R_2 = \frac{V_{in} R_{out}}{V_{in} - V_{out}}\$

\$C_1 = \frac{1}{2 \pi f_c R_{out}}\$

Where \$R_{out}\$ is the DC output impedance (\$ \omega = 0\$) and \$f_c\$ is the low-pass cutoff frequency.