Please refer to KBA229074 about IDAC current.
According to this KBA, IDAC gain is a value for calculating IDAC current and it would be set as 2.4 µA /bit, 300 nA /bit or 37.5 nA /bit on CSD v2.
To enable Auto-Calibration, IDAC current is calibrated by adjusted IDAC code.
Also Cp is fixed system value.
What document did you refer to for “37.5nA / bit to 4800nA / bit” ?
Also could you give more details about the request on your project.
We can choose the Gain IDAC value from 35.7uA/bit to 4800nA/bit on the Widget Detail Tab of CapSense v7.0 component.
The customer's application has a large capacitance due to the metal chassis near the sensor.
They use Manual Tuning method because the limit that Smart Sense can tune is up to 45pF.
If CapSense can tune a sensor of 100pF or higher with component Ver7.0, we can introduce Smart Sense to the next model.
The cp range supported by CapSense sensor is not not decided by CapSense component version, it is decided by the CSD hardware architecture version. PSoC4 none-S series(PSoC4100, PSoC4200,PSOC4AM, PSoC4AL) use third-generation csd architecture; PSoC 4 S-Series, PSoC 4100S Plus, PSoC 4100PS, and PSoC 6 MCU is an improved version of the previous generation CapSense architecture - the fourth-generation CapSense architecture. The differences of these two versions ad below:
In component datasheet, the Cp range remains min:5, max:45, this data is only for SmartSense tuning mode. If you use pure manual tuning mode or ida auto-calibration tuning mode, the maximum cp can be increases to 60pF(or even more).
Thank you for the explanation.
The target IC is 4000S series.
To summarize my understanding, the 4th Gen CapSense supports a Cp range of 5pF-200pF in the manual tuning method, but SmartSense can only tune up to 45pF.
If possible, please tell me about this limit.
Is it because SmartSense does not use the entire range of CapSense parameters (IDAC range ,Resolution, etc.)?
Yes, your understanding is correct.
SmartSense is intentionally just provided a setting which is required for CapSense as minimum. (5:1 SNR)
If Cp can be more than 45pF, it could be greater than 5:1 SNR.
You need to change to manual tuning when you want to adopt for your request.