Appendix A Electrical Characteristics
658
MC9S12C-Family / MC9S12GC-Family
Freescale Semiconductor
Rev 01.24
A.2
ATD Characteristics
This section describes the characteristics of the analog-to-digital converter.
V
RL
is not available as a separate pin in the 48- and 52-pin versions. In this case the internal V
RL
pad is
bonded to the V
SSA
pin.
The ATD is specified 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.2.1
ATD Operating Characteristics In 5V Range
The
shows conditions under which the ATD operates.
The following constraints exist to obtain full-scale, full range results: V
SSA
≤
V
RL
≤
V
IN
≤
V
RH
≤
V
DDA
.
This constraint exists since the sample buffer amplifier 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-10. ATD Operating Characteristics
Conditions are shown in
unless otherwise noted. Supply Voltage 5V-10% <= V
DDA
<=5V+10%
Num
C
Rating
Symbol
Min
Typ
Max
Unit
1
D
Reference Potential
Low
High
V
RL
V
RH
V
SSA
V
DDA/2
—
—
V
DDA/2
V
DDA
V
V
2
C
Differential Reference Voltage
(1)
1. Full accuracy is not guaranteed when differential voltage is less than 4.75V
V
RH
-V
RL
4.75
5.0
5.25
V
3
D
ATD Clock Frequency
f
ATDCLK
0.5
—
2.0
MHz
4
D
ATD 10-Bit Conversion Period
Clock Cycles
(2)
Conv, Time at 2.0MHz ATD Clock f
ATDCLK
2. The minimum time assumes a final sample period of 2 ATD clocks cycles while the maximum time assumes a final sample
period of 16 ATD clocks.
N
CONV10
T
CONV10
14
7
—
—
28
14
Cycles
µ
s
5
D
ATD 8-Bit Conversion Period
Clock Cycles
2
Conv, Time at 2.0MHz ATD Clock f
ATDCLK
N
CONV10
T
CONV10
12
6
—
—
26
13
Cycles
µ
s
5
D
Recovery Time (V
DDA
=5.0 Volts)
t
REC
—
—
20
µ
s
6
P
Reference Supply current
I
REF
—
—
0.375
mA
Summary of Contents for MC9S12C Family
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