MC68HC05V12 Datasheet, PDF (28/246 Pages) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

Freescale Semiconductor, Inc.
General Description
1.6.1 V_DD and V_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_DD and V_SS 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 V_SSA
V_SSA 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 V_CCA
V_CCA 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 V_DD pin externally. To prevent contamination from the digital supply,
this pin should be adequately decoupled to a low-impedance ground
reference.
1.6.4 V_REFH and V_REFL
V_REFH is the positive (high) reference voltage for the A/D subsystem.
V_REFL is the negative (low) reference voltage for the A/D subsystem.
V_REFH and V_REFL should be isolated from the digital supplies to prevent
any loss of accuracy from the A/D converter.
Technical Data
General Description
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MC68HC05V12 — Rev. 2.0