MC68HC705K1 Datasheet, PDF (19/140 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
General Description
Pin Assignments
1.6 Pin Assignments
Figure 1-2 shows the MC68HC705K1 pin assignments.
RESET 1
PB1/OSC3 2
PB0 3
IRQ/V_PP 4
PA0 5
PA1 6
PA2 7
PA3 8
16 OSC1
15 OSC2
14 V_SS
13 V_DD
12 PA7
11 PA6
10 PA5
9 PA4
Figure 1-2. Pin Assignments
1.6.1 V_DD and V_SS
V_DD and V_SS are the power supply and ground pins. The MCU operates
from a single 5-volt power supply.
Very fast signal transitions occur on the MCU pins, placing high
short-duration current demands on the power supply. To prevent noise
problems, take special care to provide good power supply bypassing at
the MCU. Place bypass capacitors as close to the MCU as possible, as
Figure 1-3 shows.
V+
V_DD
+
MCU
C1
C2
V_SS
OSC1
OSC2
V_SS
C1 C2
V_DD
MC68HC705K1 — Rev. 2.0
Figure 1-3. Bypassing Layout Recommendation
General Description
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Technical Data