MC68HC908GP20 Datasheet, PDF (92/406 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

5.7.1 ADC Analog Power Pin (V_DDAD)/ADC Voltage Reference High Pin (V_REFH)
The ADC analog portion uses V_DDAD as its power pin. Connect the
V_DDAD pin to the same voltage potential as V_DD. External filtering may
be necessary to ensure clean V_DDAD for good results.
NOTE: For maximum noise immunity, route V_DDAD carefully and place bypass
capacitors as close as possible to the package.
5.7.2 ADC Analog Ground Pin (V_SSAD)/ADC Voltage Reference Low Pin (V_REFL)
The ADC analog portion uses V_SSAD as its ground pin. Connect the
V_SSAD pin to the same voltage potential as V_SS.
NOTE: Route V_SSAD cleanly to avoid any offset errors.
5.7.3 ADC Voltage In (ADV_IN)
ADV_IN is the input voltage signal from one of the eight ADC channels to
the ADC module.
5.8 I/O Registers
These I/O registers control and monitor ADC operation:
• ADC status and control register (ADSCR)
• ADC data register (ADR)
• ADC clock register (ADCLK)
Advance Information
92
MC68HC908GP20 — Rev 2.1
Freescale Semiconductor