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Pinout and Signal Descriptions
Advance Information
68HC(9)12D60 — Rev 4.0
42
Pinout and Signal Descriptions
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MOTOROLA
3.4 Power Supply Pins
68HC(9)12D60 power and ground pins are described below and
summarized in
Table 3-1
.
3.4.1 Internal Power (V
DD
) and Ground (V
SS
)
Power is supplied to the MCU through V
DD
and V
SS
. Because fast signal
transitions place high, short-duration current demands on the power
supply, use bypass capacitors with high-frequency characteristics and
place them as close to the MCU as possible. Bypass requirements
depend on how heavily the MCU pins are loaded.
3.4.2 External Power (V
DDX
)
and Ground (V
SSX
)
External power and ground for I/O drivers. Because fast signal
transitions place high, short-duration current demands on the power
supply, use bypass capacitors with high-frequency characteristics and
place them as close to the MCU as possible. Bypass requirements
depend on how heavily the MCU pins are loaded.
3.4.3 V
DDA
, V
SSA
Provides operating voltage and ground for the analog-to-digital
converter. This allows the supply voltage to the ATD to be bypassed
independently. Connecting V
DDA
to V
DD
if the ATD modules are not
used will not result in an increase of power consumption.
3.4.4 Analog to Digital Reference Voltages (V
RH
, V
RL
)
V
RH0
, V
RL0
: reference voltage high and low for ATD converter 0.
V
RH1
, V
RL1
: reference voltage high and low for ATD converter 1.
If the ATD modules are not used, leaving V
RH
connected to V
DD
will not
result in an increase of power consumption.
F
Freescale Semiconductor, Inc.
n
.