# Low Pass Filter calculation

I am designing a circuit which reads a analog signal(DC - Response from a photo-diode exposed to tungsten lamp) to a 12 bit ADC. The ADC is MCP3202 running at 1Mhz speed and uses 16 input bits to get one sample of the result.

As per my calculations, I have calculated the response time of the low pass filter as shown below:

Chip Speed (Mhz)    1
Period(us : microSecond)    1
No of Process Cycles    16
Response time required (us) 16
Response time required (ns : NanoSeconds)   16000
Response time required (ms : MilliSeconds)  0.016
Response time required (Seconds)    0.000016 or 1.6E-5


I believe that if my RC circuit is slower than the above response time, then I will see a delayed response, which I should avoid. Therefore, I choose the following Resistance and Capacitor values for my RC low pass filter.

R = 1 K
C = 5 nF


The cut-off frequency is calculated as :

 fc = 31830.9886184[Hz]


The response time is calculated as:

1.1512925465E-5


Does all of the above sounds OK or am I off track here?