Multiple Channel Capacitive Touch Sensor and LED Driver
Datasheet
APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitive settings, the
MSB of the Delta Count register represents 64 out of ~25,000 which corresponds to a touch
of approximately 0.25% of the base capacitance (or a ΔC of 25fF from a 10pF base
capacitance). Conversely a value of 1x is the least sensitive setting available. At these
settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts
out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance
(or a ΔC of 3.33pF from a 10pF base capacitance).
Table 5.18 D_DSP Bit Decode
D_DSP[2:0]
2
1
0
SENSITIVITY MULTIPLIER
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
128x (most sensitive)
64x
32x (default)
16x
8x
4x
2x
1x - (least sensitive)
Bits 3 - 0 - C_DSP[3:0] - Controls the scaling and data presentation of the Base Count registers. The
higher the value of these bits, the larger the range and the lower the resolution of the data presented.
The scale factor represents the multiplier to the bit-weighting presented in these register descriptions.
APPLICATION NOTE: The C_DSP[3:0] bits normally do not need to be updated. These settings will not affect touch
detection or sensitivity. These bits are sometimes helpful in analyzing the Cap Sensing board
performance and stability.
Table 5.19 C_DSP Bit Decode
C_DSP[3:0]
DATA SCALING
3
2
1
0
FACTOR
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
1x
2x
4x
8x
16x
32x
64x
128x
SMSC CAP1014
Revision 1.65 (08-11-09)
DATA4S3HEET
SMSC [ SMSC CORPORATION ]
