K20P48M50SF0 Datasheet, PDF (55/60 Pages) Freescale Semiconductor, Inc – K20 Sub-Family

Table 40. TSI electrical specifications (continued)
Dimensions
Symbol
T_Con20
I_{TSI_RUN}
I_{TSI_LP}
Description
Response time @ 20 pF
Current added in run mode
Low power mode current adder
Min.
8
—
—
Typ.
15
55
1.3
Max.
25
—
2.5
Unit
Notes
μs
12
μA
μA
13
1. The TSI module is functional with capacitance values outside this range. However, optimal performance is not guaranteed.
2. Fixed external capacitance of 20 pF.
3. REFCHRG = 2, EXTCHRG=0.
4. REFCHRG = 0, EXTCHRG = 10.
5. V_DD = 3.0 V.
6. The programmable current source value is generated by multiplying the SCANC[REFCHRG] value and the base current.
7. The programmable current source value is generated by multiplying the SCANC[EXTCHRG] value and the base current.
8. Measured with a 5 pF electrode, reference oscillator frequency of 10 MHz, PS = 128, NSCN = 8; Iext = 16.
9. Measured with a 20 pF electrode, reference oscillator frequency of 10 MHz, PS = 128, NSCN = 2; Iext = 16.
10. Measured with a 20 pF electrode, reference oscillator frequency of 10 MHz, PS = 16, NSCN = 3; Iext = 16.
11. Sensitivity defines the minimum capacitance change when a single count from the TSI module changes. Sensitivity
depends on the configuration used. The documented values are provided as examples calculated for a specific
configuration of operating conditions using the following equation: (C_ref * I_ext)/( I_ref * PS * NSCN)
The typical value is calculated with the following configuration:
I_ext = 6 μA (EXTCHRG = 2), PS = 128, NSCN = 2, I_ref = 16 μA (REFCHRG = 7), C_ref = 1.0 pF
The minimum value is calculated with the following configuration:
I_ext = 2 μA (EXTCHRG = 0), PS = 128, NSCN = 32, I_ref = 32 μA (REFCHRG = 15), C_ref = 0.5 pF
The highest possible sensitivity is the minimum value because it represents the smallest possible capacitance that can be
measured by a single count.
12. Time to do one complete measurement of the electrode. Sensitivity resolution of 0.0133 pF, PS = 0, NSCN = 0, 1
electrode, EXTCHRG = 7.
13. 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
7.1 Obtaining package dimensions
Package dimensions are provided in package drawings.
To find a package drawing, go to http://www.freescale.com and perform a keyword
search for the drawing’s document number:
If you want the drawing for this package
48-pin LQFP
48-pin QFN
Then use this document number
98ASH00962A
98ARH99048A
K20 Sub-Family Data Sheet, Rev. 4 5/2012.
Freescale Semiconductor, Inc.
55