MC9S12A128 Datasheet, PDF (36/92 Pages) Motorola, Inc – Microcontroller unit (MCU)

MC9S12A128 Device Guide — V01.01
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 2.5V 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 V_REGEN is tied to ground.
NOTE: No load allowed except for bypass capacitors.
2.4.4 V_DDA, V_SSA — Power Supply Pins for ATD and VREG
V_DDA, V_SSA are the power supply and ground input pins for the voltage regulator and the analog to digital
converter. It also provides the reference for the internal voltage regulator. This allows the supply voltage
to the ATD and the reference voltage to be bypassed independently.
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.
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 2.5V voltage is generated by
the internal voltage regulator.
NOTE: No load allowed except for bypass capacitors.
2.4.7 V_REGEN — On Chip Voltage Regulator Enable
Enables the internal 5V to 2.5V voltage regulator. If this pin is tied low, V_DD1,2 and V_DDPLL must be
supplied externally.
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