There is any way to calculate this?
As of now, there is only one Delta Sigma ADC available in PSoC3. You will have to use the Analog Mux and multiplex to measure multiple channels. However, using the combination of SC/CT block and DFB, it should be possible to create incremental ADCs similar to PSoC1. But I do not have enough information regarding when such ADCs will be available or how many such ADCs can be placed in the project.
Additionally, we do have an implementation of a triple SAR ADC in the larger PSoC 3 parts (CY8C36 and CY8C38 parts) using a DAC, comparator and a UDB--gotta love the programmable analog signal chain! We're working on the testing, documentation and finalizing the component. We should be bringing it out in a future PSoC Creator updates...but it's testing and other schedules are not quite firmed up yet. I'll keep this thread updated when it's out or scheduled. So, add these 3 SAR ADCs (really 4 ADCs if you use up all your DACs and comparators), the 4 you can get using Ganesh's response with the Incremental ADCs and then the DelSig ADC; that's up to at least 9 ADCs in total for the larger PSoC 3 families (CY8C36 and CY8C38).