Freescale Semiconductor MC9S08PT60, Reference Manual

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Table 19-1. Signal Properties
Name Function
AD23–AD0 Analog Channel inputs
V
REFH
High reference voltage
V
REFL
Low reference voltage
V
DDA
Analog power supply
V
SSA
Analog ground
19.2.1 Analog Power (V
DDA
)
The ADC analog portion uses V
DDA
as its power connection. In some packages, V
DDA
is
connected internally to V
DD
. If externally available, connect the V
DDA
pin to the same
voltage potential as V
DD
. External filtering may be necessary to ensure clean V
DDA
for
good results.
19.2.2 Analog Ground (V
SSA
)
The ADC analog portion uses V
SSA
as its ground connection. In some packages, V
SSA
is
connected internally to V
SS
. If externally available, connect the V
SSA
pin to the same
voltage potential as V
SS
.
19.2.3 Voltage Reference High (V
REFH
)
V
REFH
is the high reference voltage for the converter. In some packages, V
REFH
is
connected internally to V
DDA
. If externally available, V
REFH
may be connected to the
same potential as V
DDA
or may be driven by an external source between the minimum
V
DDA
specified in the data sheet and the V
DDA
potential (V
REFH
must never exceed
V
DDA
).
19.2.4 Voltage Reference Low (V
REFL
)
V
REFL
is the low-reference voltage for the converter. In some packages, V
REFL
is
connected internally to V
SSA
. If externally available, connect the V
REFL
pin to the same
voltage potential as V
SSA
.
Chapter 19 Analog-to-digital converter (ADC)
MC9S08PT60 Reference Manual, Rev. 4, 08/2014
Freescale Semiconductor, Inc. 539