
Appendix A Electrical Characteristics
MC9S12E128 Data Sheet, Rev. 1.07
Freescale Semiconductor
589
A.6
ATD Characteristics
This section describes the characteristics of the analog to digital converter.
The ATD is specied and tested for both the 3.3V and 5V range. For ranges between 3.3V and 5V the ATD
accuracy is generally the same as in the 3.3V range but is not tested in this range in production test.
A.6.1
ATD Operating Characteristics — 5V Range
The
Table A-19 shows conditions under which the ATD operates.
The following constraints exist to obtain full-scale, full range results:
VSSA
≤ VRL ≤ VIN ≤ VRH ≤ VDDA. This constraint exists since the sample buffer amplier can not
drive beyond the power supply levels that it ties to. If the input level goes outside of this range it will
effectively be clipped.
Table A-19. 5V ATD Operating Characteristics
Conditions are shown in
Table A-4 unless otherwise noted. Supply Voltage 5V-10% <= VDDA <=5V+10%
Num C
Rating
Symbol
Min
Typ
Max
Unit
1
D Reference Potential
Low
High
VRL
VRH
VSSA
VDDA/2
—
VDDA/2
VDDA
V
2
C Differential Reference Voltage1
1 Full accuracy is not guaranteed when differential voltage is less than 4.75V
VRH–VRL
4.75
5.0
5.25
V
3
D ATD Clock Frequency
fATDCLK
0.5
—
2.0
MHz
4D ATD 10-Bit Conversion Period
Clock Cycles2
Conv, Time at 2.0MHz ATD Clock fATDCLK
Conv, Time at 4.0MHz3 ATD Clock fATDCLK
2 The minimum time assumes a nal sample period of 2 ATD clocks cycles while the maximum time assumes a nal sample
period of 16 ATD clocks.
NCONV10
TCONV10
14
7
3.5
—
28
14
7
Cycles
s
5
D ATD 8-Bit Conversion Period
Conv, Time at 2.0MHz ATD Clock fATDCLK
NCONV8
TCONV8
12
6
—
26
13
Cycles
s
6
D Stop Recovery Time (VDDA = 5.0 Volts)
tSR
——
20
s
7
P Reference Supply current
IREF
—
0.375
mA