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hello,every one.
I captured the Cmod voltage wave from CY3280-21x34 at the CY3280-BK1 board,just as below.
While according to 《Cypress’ CapSense Sigma-Delta Algorithm》,the wave should like this.
they are very different.
how to explain the Oscilloscope wave?
Solved! Go to Solution.
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Hi beyows_2639911,
CY8C21X34 uses first generation CSD structure( with Rbleed resistor). In this structure, Vref connected to delta-sigma comparator is adjustable based on the component config (Reference and Ref Value parameter). Hence CMOD voltage not being equal to 1.2 V is expected.
CMOD pin will be shorted to GND to fully discharge. Hence the negative pulse, at the end of each scan cycle is also expected.
Regards,
Bragadeesh
Bragadeesh
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Hi beyows_2639911,
CY8C21X34 uses first generation CSD structure( with Rbleed resistor). In this structure, Vref connected to delta-sigma comparator is adjustable based on the component config (Reference and Ref Value parameter). Hence CMOD voltage not being equal to 1.2 V is expected.
CMOD pin will be shorted to GND to fully discharge. Hence the negative pulse, at the end of each scan cycle is also expected.
Regards,
Bragadeesh
Bragadeesh