HC05V12GRSSLASHD datasheet(26/240 Pages) NXP

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General Description

General Release Specification

MC68HC05V12 — Rev. 1.0

General Description

1.6.1 VDD and VSSD

These pins provide power to all the microcontroller’s digital circuits. The

short rise and fall times of the MCU supply current transients place very

high short-duration current demands on the internal power supply. To

prevent noise problems, special care should be taken to provide good

power supply bypassing at the MCU by using bypass capacitors with

good high-frequency characteristics that are positioned as close to the

MCU supply pins as possible. Two sets of VDD and VSS pins are required

to maintain on-chip supply noise within acceptable limits. Each supply

pin pair will require its own decoupling capacitor. These are high-current

pins.

1.6.2 VSSA

VSSA is a separate ground pad which provides a ground return for the

analog-to-digital (A/D) subsystem and the digital-to-analog (D/A) gauge

subsystem. To prevent digital noise contamination, this pin should be

connected directly to a low-impedance ground reference point.

1.6.3 VCCA

VCCA is a separate supply pin providing power to the analog subsystems

of the A/D converter and gauge drivers. This pin must be connected to

the VDD pin externally. To prevent contamination from the digital supply,

this pin should be adequately decoupled to a low-impedance ground

reference.

1.6.4 VREFH and VREFL

VREFH is the positive (high) reference voltage for the A/D subsystem.

VREFL is the negative (low) reference voltage for the A/D subsystem.

VREFH and VREFL should be isolated from the digital supplies to prevent

any loss of accuracy from the A/D converter.

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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