Chapter 1 MC9S12XF-Family Reference Manual
MC9S12XF - Family Reference Manual, Rev.1.19
Freescale Semiconductor
63
1.2.9
Power Supply Pins
The power and ground pins of the MC9S12XF512 are described below.
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.
NOTE
All VSS pins must be connected together in the application.
1.2.9.1
VDDX1 - VDDX4 / VSSX1 - VSSX4 — Power & Ground Pins for I/O Drivers
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.
1.2.9.2
VDDR — Power Pin for Internal Voltage Regulator
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.
NOTE
Usage of an external voltage regulator is not allowed.
1.2.9.3
VDDF - NVM Power Pin
Power is supplied to the MCU NVM through VDDF. The voltage supply of nominally 2.8V is derived from
the internal voltage regulator when enabled. Connecting additional load to this pin is not permitted when
the internal regulator is enabled.
NOTE
VDDF must not be connected to VDD.
1.2.9.4
VDD / VSS1 - VSS2 - VSS3 — Core Power Pins
Use bypass capacitors with high-frequency characteristics because fast signal transitions place high, short-
duration current demands on the power supply, and place them as close to the MCU as possible. This 1.8V
supply is derived from the internal voltage regulator when enabled. Connecting additional load to this pin
is not permitted when the internal regulator is enabled.
NOTE
VDD must not be connected to VDDF.