MC9S12B128_05 Datasheet, PDF (63/132 Pages) Motorola, Inc – Covers also preliminary MC9S12B64 using MC9S12B128 die

Device User Guide —9S12B128DGV1/D V01.13
2.3.3 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.
2.3.4 VDDA, VSSA — Power Supply Pins for ATD and VREG
VDDA, VSSA are the power supply and ground input pins for the voltage regulator and the two analog to
digital converters. It also provides the reference for the internal voltage regulator. This allows the supply
voltage to ATD0/ATD1 and the reference voltage to be bypassed independently.
2.3.5 VRH, VRL — ATD Reference Voltage Input Pins
VRH and VRL are the reference voltage input pins for the analog to digital converter.
2.3.6 VDDPLL, VSSPLL — 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.
2.3.7 VREGEN — On Chip Voltage Regulator Enable
Enables the internal 5V to 2.5V voltage regulator. If this pin is tied low, VDD1,2 and VDDPLL must be
supplied externally.
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