MC68HC908EY16 Datasheet, PDF (48/278 Pages) Motorola, Inc – Microcontrollers

Analog-to-Digital Converter (ADC) Module
3.5 Wait Mode
The WAIT instruction can put the MCU in low power-consumption standby mode.
The ADC continues normal operation during wait mode. Any enabled CPU interrupt request from the ADC
can bring the MCU out of wait mode. If the ADC is not required to bring the MCU out of wait mode, power
down the ADC by setting ADCH[4:0] in the ADC status and control register before executing the WAIT
instruction.
3.6 I/O Signals
The ADC module has eight input signals.
3.6.1 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.
3.6.2 ADC Analog Ground Pin (V_SSA)
The ADC analog portion uses V_SSA as its ground pin. Connect the V_SSA pin to the same voltage potential
as V_SS.
3.6.3 ADC Voltage Reference 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 Chapter 20 Electrical
Specifications.
NOTE
Route V_REFH carefully for maximum noise immunity and place bypass
capacitors as close as possible to the package.
3.6.4 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. A finite current will be associated with V_REFL. See Chapter 20 Electrical Specifications.
3.6.5 ADC Voltage In (ADVIN)
ADVIN is the input voltage signal from one of the 8 ADC channels to the ADC module.
3.6.6 ADC External Connections
This section describes the ADC external connections: V_REFH and V_REFL, ANx, and grounding.
MC68HC908EY16 • MC68HC908EY8 Data Sheet, Rev. 10
48
Freescale Semiconductor