Datasheet

Typically, application systems have two separate capacitors across the power pins. In this
case, there should be a bulk electrolytic capacitor, such as a 10 µF tantalum capacitor,
that provides bulk charge storage for the overall system and a 0.1 µF ceramic bypass
capacitor located as near to the paired V
DD
and V
SS
power pins as practical to suppress
high-frequency noise.
MCU
C1
C2
V
DD
V
ss
V
DD
0.1
F
Figure 2-5. Power supply bypassing
2.2.2 Analog power supply and reference pins (V
DDA
/V
REFH
and
V
SSA
/V
REFL
)
V
DDA
and V
SSA
are the power supply pins for the analog-to-digital converter (ADC).
Connect the V
DDA
pin to the same voltage potential as V
DD
, and the V
SSA
pin to the same
voltage potential as V
SS
.
De-coupling of these pins should be as per the digital supply. A 0.1 µF ceramic bypass
capacitor should be located as near to the MCU power pins as practical to suppress high-
frequency noise.
MCU
C1
V
DDA /V
REFH
V
SSA /V
REFL
F
0.1
External reference voltage
Figure 2-6. Analog power supply bypassing
V
REFH
is the high reference supply for the ADC, and is internally connected to V
DDA
.
V
REFL
is the low reference supply for the ADC, and is internally connected to V
SSA
.
Pin functions
MC9S08PA60 Reference Manual, Rev. 1, 9/2012
44 Freescale Semiconductor, Inc.