
MOTOROLA
10
MC68HC912B32
MC68HC912B32TS/D
3.2 Power Supply Pins
MC68HC912B32 power and ground pins are described below and summarized in
Table 4
.
3.2.1 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 character-
istics and place them as close to the MCU as possible. Bypass requirements depend on how heavily
the MCU pins are loaded.
3.2.2 External Power (V
DDX
)
and Ground (V
SSX
)
External power and ground for I/O drivers. Because fast signal transitions place high, short-duration cur-
rent 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.
3.2.3 V
DDA
, V
SSA
Provides operating voltage and ground for the analog-to-digital converter. This allows the supply volt-
age to the A/D to be bypassed independently.
3.2.4 Analog-to-Digital Reference Voltages (V
RH
, V
RL
)
3.2.5 V
FP
Flash EEPROM programming voltage and supply voltage during normal operation.
3.2.6 V
PP
High voltage supply to EEPROM. Used to monitor charge pump output and testing. Not intended for
general applications use.
Table 4 MC68HC912B32 Power and Ground Connection Summary
Mnemonic
V
DD
V
SS
V
DDX
V
SSX
V
DDA
V
SSA
V
RH
V
RL
Pin Number
Description
10, 47
Internal power and ground.
11, 48
31, 78
External power and ground, supply to pin drivers.
30, 77
59
Operating voltage and ground for the analog-to-digital converter,
allows the supply voltage to the A/D to be bypassed independently.
60
49
Reference voltages for the analog-to-digital converter.
50
V
FP
69
Programming voltage for the Flash EEPROM and required supply
for normal operation.
High voltage supply to EEPROM used for test purposes only in
special modes.
V
PP
37