Original question:
Tool/software:
Hi Ti Team
Is it correct that if I use/need only 60 of the 128 coefficients of the FIR3 Filter it uses all 128 for calculation and the latency is always 68 / fDATA + 16 / fCLK?! Or does it shorten the latency to 30 / fDATA + 16 / fCLK?
Regards Theo
Hello Theo,
Yes, when using the programmable FIR3 filter coefficients, the latency will always be the maximum value based on 128 coefficients, however, the latency will be 75 / fDATA + 16 / fCLK.
When using the default coefficients, the latency is 68 / fDATA + 16 / fCLK, which is less than the programmable option since the number of coefficients used for the default FIR3 filter are less than 128.
When using the programmable option, the ADS127L21 does not have logic to determine how many of the coefficients are used, and will always default to the maximum latency for 128 coefficients, or a latency of 75 / fDATA + 16 / fCLK.
Regards,
Keith Nicholas
Precision ADC Applications
