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Chapter 1 Device Overview (MC9S12XDP512V2)
MC9S12XDP512 Data Sheet, Rev. 2.11
Freescale Semiconductor 89
1.2.4.2 V
DDR1
, V
DDR2
, V
SSR1
, V
SSR2
— Power and Ground Pins for I/O Drivers
and 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.
1.2.4.3 V
DD1
, V
DD2
, V
SS1
, V
SS2
— Core Power Pins
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. This 2.5-V 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 V
REGEN
is tied to ground.
NOTE
No load allowed except for bypass capacitors.
1.2.4.4 V
DDA
, V
SSA
— Power Supply Pins for ATD and V
REG
V
DDA
,V
SSA
are the power supply and ground input pins for the voltage regulator and the analog-to-digital
converters.
1.2.4.5 V
RH
, V
RL
— ATD Reference Voltage Input Pins
V
RH
and V
RL
are the reference voltage input pins for the analog-to-digital converter.
1.2.4.6 V
DDPLL
, V
SSPLL
— Power Supply Pins for PLL
Provides operating voltage and ground for the oscillator and the phased-locked loop. This allows the
supply voltage to the oscillator and PLL to be bypassed independently. This 2.5-V voltage is generated by
the internal voltage regulator.
NOTE
No load allowed except for bypass capacitors.
1.2.4.7 V
REGEN
— On--Chip Voltage Regulator Enable
Enables the internal 5 V to 2.5 V voltage regulator. If this pin is tied low, V
DD1,2
and V
DDPLL
must be
supplied externally.