K20P81M100SF2_1109 Datasheet, PDF (64/75 Pages) Freescale Semiconductor, Inc – K20 Sub-Family Data Sheet

Dimensions
Table 47. TSI electrical specifications (continued)
Symbol
C_REF
V_DELTA
I_REF
Description
Internal reference capacitor
Oscillator delta voltage
Reference oscillator current source base current
• 1uA setting (REFCHRG=0)
• 32uA setting (REFCHRG=31)
I_ELE Electrode oscillator current source base current
• 1uA setting (EXTCHRG=0)
• 32uA setting (EXTCHRG=31)
Pres5 Electrode capacitance measurement precision
Pres20 Electrode capacitance measurement precision
Pres100 Electrode capacitance measurement precision
MaxSens Maximum sensitivity
Res Resolution
T_Con20 Response time @ 20 pF
I_{TSI_RUN} Current added in run mode
I_{TSI_LP} Low power mode current adder
Min.
0.5
100
—
—
—
—
—
—
—
0.003
—
8
—
—
Typ.
1
600
1.133
36
1.133
36
8.3333
8.3333
8.3333
12.5
—
15
55
1.3
Max.
1.2
760
1.5
50
1.5
50
38400
38400
38400
—
16
25
—
2.5
Unit
pF
mV
μA
μA
%
%
%
fF/count
bits
μs
μA
μA
Notes
4
3, 5
3,6
7
8
9
10
11
12
1. The TSI module is functional with capacitance values outside this range. However, optimal performance is not guaranteed.
2. CAPTRM=7, DELVOL=7, and fixed external capacitance of 20 pF.
3. CAPTRM=0, DELVOL=2, and fixed external capacitance of 20 pF.
4. CAPTRM=0, EXTCHRG=9, and fixed external capacitance of 20 pF.
5. The programmable current source value is generated by multiplying the SCANC[REFCHRG] value and the base current.
6. The programmable current source value is generated by multiplying the SCANC[EXTCHRG] value and the base current.
7. Measured with a 5 pF electrode, reference oscillator frequency of 10 MHz, PS = 128, NSCN = 8; Iext = 16.
8. Measured with a 20 pF electrode, reference oscillator frequency of 10 MHz, PS = 128, NSCN = 2; Iext = 16.
9. Measured with a 20 pF electrode, reference oscillator frequency of 10 MHz, PS = 16, NSCN = 3; Iext = 16.
10. Sensitivity defines the minimum capacitance change when a single count from the TSI module changes, it is equal to (C_ref
* I_ext)/( I_ref * PS * NSCN). Sensitivity depends on the configuration used. The typical value listed is based on the following
configuration: Iext = 5 μA, EXTCHRG = 4, PS = 128, NSCN = 2, I_ref = 16 μA, REFCHRG = 15, C_ref = 1.0 pF. The
minimum sensitivity describes the smallest possible capacitance that can be measured by a single count (this is the best
sensitivity but is described as a minimum because it’s the smallest number). The minimum sensitivity parameter is based
on the following configuration: I_ext = 1 μA, EXTCHRG = 0, PS = 128, NSCN = 32, I_ref = 32 μA, REFCHRG = 31, C_ref= 0.5
pF
11. Time to do one complete measurement of the electrode. Sensitivity resolution of 0.0133 pF, PS = 0, NSCN = 0, 1
electrode, DELVOL = 2, EXTCHRG = 15.
12. CAPTRM=7, DELVOL=2, REFCHRG=0, EXTCHRG=4, PS=7, NSCN=0F, LPSCNITV=F, LPO is selected (1 kHz), and
fixed external capacitance of 20 pF. Data is captured with an average of 7 periods window.
7 Dimensions
K20 Sub-Family Data Sheet Data Sheet, Rev. 6, 9/2011.
64
Freescale Semiconductor, Inc.