MC9S12DT128 Device User Guide — V02.09
73
NOTE:
All VSS pins must be connected together in the application.
2.4.1 VDDX,VSSX — Power & Ground Pins for I/O Drivers
External power and ground for I/O drivers. Because fast signal transitions place high, short-duration
currentdemandsonthepowersupply,usebypasscapacitorswithhigh-frequencycharacteristicsandplace
them as close to the MCU as possible. Bypass requirements depend on how heavily the MCU pins are
loaded.
2.4.2 VDDR, VSSR — Power & Ground Pins for I/O Drivers & for Internal
Voltage Regulator
External power and ground for I/O drivers and input to the internal voltage regulator. 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.
2.4.3 VDD1, VDD2, VSS1, VSS2 — Internal Logic Power Supply Pins
Power is supplied to the MCU through VDD and VSS. 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. This 2.5V supply is derived from the
internal voltage regulator. There is no static load on those pins allowed. The internal voltage regulator is
turned off, if VREGEN is tied to ground.
NOTE:
No load allowed except for bypass capacitors.
VDDR
VSSR
VDDX
VSSX
VDDA
41
40
107
106
83
5.0V
0V
5.0V
0V
5.0V
External power and ground, supply to pin drivers and internal
voltage regulator.
External power and ground, supply to pin drivers.
Operating voltage and ground for the analog-to-digital
converters and the reference for the internal voltage regulator,
allows the supply voltage to the A/D to be bypassed
independently.
VSSA
86
0V
VRL
VRH
VDDPLL
85
84
43
0V
5.0V
2.5V
Reference voltages for the analog-to-digital converter.
Provides operating voltage and ground for the Phased-Locked
Loop. This allows the supply voltage to the PLL to be
bypassed independently. Internal power and ground
generated by internal regulator.
Internal Voltage Regulator enable/disable
VSSPLL
45
0V
VREGEN
97
5V
Mnemonic
Pin Number
112-pin QFP
Nominal
Voltage
Description