Freescale Semiconductor, Inc.
Ge ne ra l De sc rip tion
1.6.1 V a nd V
DD
SSD
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 V and V pins are required
DD
SS
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 V
SSA
V
is a separate ground pad which provides a ground return for the
SSA
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 V
CCA
V
is a separate supply pin providing power to the analog subsystems
CCA
of the A/D converter and gauge drivers. This pin must be connected to
the V pin externally. To prevent contamination from the digital supply,
DD
this pin should be adequately decoupled to a low-impedance ground
reference.
1.6.4 V
a nd V
REFL
REFH
V
V
V
is the positive (high) reference voltage for the A/D subsystem.
is the negative (low) reference voltage for the A/D subsystem.
REFH
REFL
REFH
and V
should be isolated from the digital supplies to prevent
REFL
any loss of accuracy from the A/D converter.
General Release Specification
MC68HC05V12 — Rev. 1.0
General Description
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