Datasheet

CY8C20xx6A/H CapSense Design Guide Doc. No. 001-65973 Rev. *A 22
Table 3-1. Resolution and Scan Speed
Scan Speed (µs)
Resolution Ultra Fast Fast Normal Slow
9 57 78 125 205
10 78 125 205 380
11 125 205 380 720
12 205 380 720 1400
13 380 720 1400 2800
14 720 1400 2800 5600
15 1400 2800 5600 11000
16 2800 5600 11000 22000
3.5.3 Scanning Speed
This parameter sets sensor scanning speed. While faster scanning speed provides good response time, slower
scanning speeds provide the following advantages:
 Improved SNR
 Better immunity to power supply and temperature changes
 Less demand for system interrupt latency; you can handle longer interrupts
Possible values are Ultra Fast, Fast, Normal, and Slow.
3.5.4 Shield Electrode Out
A shield electrode is used to reduce parasitic capacitance. This parameter selects where to route the output of the
shield electrode.
Possible values are P0[7] or P1[2].
3.5.5 Precharge Source
This parameter selects the clock source for precharge switches.
Possible values are PRS and Prescaler. Use the PRS source in most cases to get better EMI immunity and lower
emission.
3.5.6 Prescaler
This parameter sets the prescaler ratio and determines the precharge switch output frequency. This parameter also
affects the PRS output frequency.
Possible values are 1, 2, 4, 8, 16, 32, 64, 128, and 256.
3.5.7 PRS Resolution
This parameter changes the PRS sequence length.
Possible values are 8-bit and 12-bit. Corresponding sequence lengths are 511 and 2047 input clock periods. Use an
8-bit setting if 12-bit does not provide good SNR.
3.5.8 Autocalibration
When Autocalibration is enabled, the Raw Count value is normalized as a percentage of the max count (2
N–1
When Autocalibration is disabled, the Raw Count value depends on iDAC Range, iDAC value, resolution, sensor
capacitance, IMO frequency, prescaler, precharge source, and V
) where
N is the resolution. Autocalibration overrides the device editor settings.
ref
parameters set in the device editor.