MC68HC908LJ12 Datasheet, PDF (308/413 Pages) Freescale Semiconductor, Inc – 8-bit microcontroller units

Analog-to-Digital Converter (ADC)
15.7.1 ADC Voltage In (V_ADIN)
V_ADIN is the input voltage signal from one of the nine channels to the
ADC module.
15.7.2 ADC Analog Power Pin (V_DDA)
The ADC analog portion uses V_DDA as its power pin. Connect the V_DDA
pin to the same voltage potential as V_DD. External filtering may be
necessary to ensure clean V_DDA for good results.
NOTE: Route V_DDA carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
15.7.3 ADC Voltage Reference High Pin (V_REFH)
V_REFH is the power supply for setting the reference voltage V_REFH.
Connect the V_REFH pin to the same voltage potential as V_DDA. There will
be a finite current associated with V_REFH (see Section 23. Electrical
Specifications).
NOTE: Route V_REFH carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
15.7.4 ADC Voltage Reference Low Pin (V_REFL)
V_REFL is the lower reference supply for the ADC. Connect the V_REFL pin
to the same voltage potential as V_SSA. There will be a finite current
associated with V_REFL (see Section 23. Electrical Specifications).
MC68HC908LJ12 — Rev. 2.1
Freescale Semiconductor
Analog-to-Digital Converter (ADC)
Technical Data
309