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MC68HC908GT16 Datasheet, PDF (94/412 Pages) Motorola, Inc – Microcontrollers
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Analog-to-Digital Converter (ADC)
5.7.1 ADC Analog Power Pin (VDDA)
The ADC analog portion uses VDDA as its power pin. Connect the VDDA
pin to the same voltage potential as VDD. External filtering may be
necessary to ensure clean VDDA for good results.
NOTE: For maximum noise immunity, route VDDA carefully and place bypass
capacitors as close as possible to the package.
5.7.2 ADC Analog Ground Pin (VSSA)
The ADC analog portion uses VSSA as its ground pin. Connect the VSSA
pin to the same voltage potential as VSS.
NOTE: Route VSSA cleanly to avoid any offset errors.
5.7.3 ADC Voltage Reference High Pin (VREFH)
The ADC analog portion uses VREFH as its upper voltage reference pin.
The VREFH pin can be connected to an external precision reference or to
the same voltage potential as VDDA. External filtering is often necessary
to ensure a clean VREFH for good results. Any noise present on this pin
will be reflected and possibly magnified in A/D conversion values.
NOTE:
For maximum noise immunity, route VREFH carefully and place bypass
capacitors as close as possible to the package. Routing VREFH close
and parallel to VREFL may improve common mode noise rejection.
5.7.4 ADC Voltage Reference Low Pin (VREFL)
The ADC analog portion uses VREFL as its lower voltage reference pin.
The VREFL pin should be connected to the same voltage potential as
VSSA. External filtering is often necessary to ensure a clean VREFL for
good results. Any noise present on this pin will be reflected and possibly
magnified in A/D conversion values.
NOTE: For maximum noise immunity, route VREFL carefully and, if not
connected to VSS, place bypass capacitors as close as possible to the
Technical Data
94
MC68HC908GT16 • MC68HC908GT8 — Rev. 2
Analog-to-Digital Converter (ADC)
MOTOROLA
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