mc9s12vr48 Freescale Semiconductor, Inc, mc9s12vr48 Datasheet - Page 525

• Manufacturer Part Number: mc9s12vr48
• Description: S12 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Appendix C
ATD Electrical Specifications
This section describes the characteristics of the analog-to-digital converter.
C.1
The
The following constraints exist to obtain full-scale, full range results:
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.
1
2
C.2
Source resistance, source capacitance and current injection have an influence on the accuracy of the ATD.
A further factor is that PortAD pins that are configured as output drivers switching.
Freescale Semiconductor
Supply voltage 3.13 V < V
Num C
Full accuracy is not guaranteed when differential voltage is less than 4.50 V
The minimum time assumes a sample time of 4 ATD clock cycles. The maximum time assumes a sample time of 24 ATD clock
cycles and the discharge feature (SMP_DIS) enabled, which adds 2 ATD clock cycles.
1
2
3
4
5
6
Table C-1
D Reference potential
D Voltage difference V
D Voltage difference V
C Differential reference voltage
C ATD Clock Frequency (derived from bus clock via the
D
V
SSA
prescaler bus)
ATD Conversion Period
10 bit resolution:
8 bit resolution:
ATD Operating Characteristics
Factors Influencing Accuracy
Low
High
≤ V
and
RL
Table C-2
≤ V
DDA
IN
< 5.5 V, -40
DDX
SSX
≤ V
show conditions under which the ATD operates.
to V
to V
Rating
RH
2
MC9S12VR Family Reference Manual, Rev. 2.2
Table C-1. ATD Operating Characteristics
SSA
Preliminary - Subject to Change Without Notice
DDA
1
≤ V
o
C < T
DDA
J
< 150
.
o
C
N
V
Symbol
N
f
∆
∆
ATDCLk
RH
CONV10
CONV8
V
V
VDDX
VSSX
RH
RL
-V
RL
V
–2.35
V
–0.1
3.13
0.25
DDA
Min
19
17
SSA
/2
Typ
5.0
—
—
0
0
V
V
Max
DDA
0.1
0.1
5.5
8.0
41
39
DDA
/2
Cycles
clock
MHz
Unit
ATD
V
V
V
V
V
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