Datasheet

Chapter 2 External Signal Description
MC9S08QD4 Series MCU Data Sheet, Rev. 6
20 Freescale Semiconductor
Figure 2-2. Basic System Connections
2.2.1 Power
V
DD
and V
SS
are the primary power supply pins for the MCU. This voltage source supplies power to all
I/O buffer circuitry, the ADC module, and to an internal voltage regulator. The internal voltage regulator
provides regulated lower-voltage source to the CPU and other internal circuitry of the MCU.
Typically, application systems have two separate capacitors across the power pins: a bulk electrolytic
capacitor, such as a 10μF tantalum capacitor, to provide bulk charge storage for the overall system, and a
bypass capacitor, such as a 0.1μF ceramic capacitor, located as near to the MCU power pins as practical
to suppress high-frequency noise.
V
DD
V
SS
RESET
OPTIONAL
MANUAL
RESET
PORT
A
V
DD
BACKGROUND HEADER
C
BY
0.1 μF
C
BLK
10 μF
+
5 V
+
SYSTEM
POWER
I/O AND
PERIPHERAL
INTERFACE TO
SYSTEM
APPLICATION
PTA0/KBI1P0/TPM1CH0/ADC1P0
PTA1/KBI1P1/TPM1CH1/ADC1P1
PTA2/KBI1P2/TCLK1/ADC1P2
PTA3/KBI1P3/TCLK2/ADC1P3
V
DD
PTA4/TPM2CH0O/BKGD/MS
PTA5/TPM2CH0I/IRQ/RESET
MC9S08QD4
BKGD
NOTE 2
NOTES:
1. RESET
pin can only be used to reset into user mode, you can not enter BDM using RESET pin. BDM can
be entered by holding MS low during POR or writing a 1 to BDFR in SBDFR with MS low after issuing BDM
command.
2. IRQ has optional internal pullup/pulldown device
IRQ
ASYNCHRONOUS
INTERRUPT
INPUT
NOTE 1