HCS12 datasheet(70/126 Pages) NXP

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Device User Guide — 9S12KT256DGV1/D V01.09

Freescale Semiconductor

2.4.1 VDDX,VSSX — Power Supply 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.

2.4.2 VDDR, VSSR — Power Supply 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 — Power Supply Pins for Internal Logic

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.

2.4.4 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 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 VRH, VRL — ATD Reference Voltage Input Pins

VRH and VRL are the reference voltage input pins for the analog to digital converter.

2.4.6 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.

HCS12 Datasheet(PDF) 70 Page - NXP Semiconductors