qt1100a Quantum Research Group, qt1100a Datasheet - Page 32

• Manufacturer Part Number: qt1100a
• Description: 10 Key Qtouch? Sensor Ic
• Manufacturer: Quantum Research Group

Table 4-2 NTHR Ratiometric Threshold Values
This section assumes bit NTM = 1 (in byte 32 - see Table 4-1). Threshold values established by the NTHR Setup are made in terms of signal deviation expressed as a percentage
of the reference value. This gives key sensitivity a great tolerance towards part variances, deviations in Cs , and to a good extent, Cx. Settings are subject to a minimum of 3 counts
of signal, which can come into play with short burst lengths and low percentages. The values are as follows:
If NTM = 0, the threshold is based on the raw numerical value entered for each channel in the NTHR parameter in Setup bytes 0..9 plus 5 co unts, and can thus range from
5 to 20 (0 + 5... 15 + 5). NTM = 0 (the default setting) is useful in standalone applications, where key gains are adjusted by changing the value of Cs or Cx for each key.
4.17 Timing Tables
Lookup tables (LUTs) translate several Setups values into actual internal parameters. NDCR example: BS = 4ms, NDCR = 6. The actual NDCR is then 2.46s per adjustment.
Table 4-3 NDCR Negative Drift Compensation Rate Lookup Table (LUT)
LQ
Gray numbers are preferred values for most touch control applications
✁ ✁ ✁ ✁
Percentage of Reference
Setups
Value
1.23
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
Setup Value
Sensitivity
BS = 2ms
Disabled
0.45
0.57
0.69
0.81
0.99
1.23
1.47
1.83
2.25
2.73
3.33
4.11
5.07
6.21
7.65
disabled
0
-
6.25%
1
BS = 2.5ms
Disabled
0.56
0.71
0.86
1.01
1.24
1.54
1.84
2.29
2.81
3.41
4.16
5.14
6.34
7.76
9.56
5.47%
2
4.69%
BS = 3ms
3
Disabled
11.48
0.67
0.85
1.04
1.22
1.49
1.85
2.21
2.75
3.38
4.10
4.99
6.16
7.60
9.31
3.91%
4
NDCR Time, Seconds
BS = 3.5ms
3.13%
Disabled
5
10.87
13.39
0.79
1.00
1.21
1.42
1.73
2.15
2.57
3.20
3.94
4.78
5.83
7.19
8.87
Less sensitive
2.73%
32
6
BS = 4ms
Disabled
2.34%
10.14
12.42
15.30
7
0.90
1.14
1.38
1.62
1.98
2.46
2.94
3.66
4.50
5.46
6.66
8.22
1.95%
8
BS = 5ms
Disabled
More sensitive
1.56%
10.28
12.68
15.53
19.13
1.13
1.43
1.73
2.03
2.48
3.08
3.68
4.58
5.62
6.82
8.32
9
1.37%
10
BS = 6ms
Disabled
12.33
15.21
18.63
22.95
1.35
1.71
2.07
2.43
2.97
3.69
4.41
5.49
6.75
8.19
9.99
1.17%
11
0.98%
Copyright © 2003-2005 QRG Ltd
12
BS = 7ms
Disabled
11.66
14.39
17.75
21.74
26.78
1.58
2.00
2.42
2.84
3.47
4.31
5.14
6.40
7.87
9.55
0.78%
QT1100A-ISG R3.02/1105
13
0.59%
14
Value
LUT
-103
-127
-11
-13
-16
-20
-24
-30
-37
-45
-55
-68
-84
-7
-9
0
0.39%
15