Capacitance in the SC Block

[SaKu_291986]

 What is the actual value of the capacitance in the PSoC 1 switched capacitor block? (ACAP, BCAP, FCAP)

[ETRO_SSN583]

This ap note shows the values -

       

http://www.cypress.com/?rID=2899

       

Regards, Dana.

[EmDr_1490911]

No, it does not. According to the SCBLOCK user module datasheet, the unit capacitance is about 70fF

[DennisS_46]

The values listed in all of the switched cap block descriptions, user modules, and application notes are integer values for the number of UNITs of capacitance. All of the transfer functions, ADC, filter, DAC, whatever, rely on the ratios of these caps. The actual value is unimportant. That said, the UNIT cap value in a switched cap block is approximately (very approximately) 50 fF (yes femto Farads). Thus the Fcap can be either 16 or 32 units, roughly 0.8 or 1.6 pF. The unit cap could be double that and it would not affect the performance.

   

---- Dennis