MC68HC11E0CFNE3 Datasheet, PDF (21/242 Pages) Freescale Semiconductor, Inc – M68HC11E Family

Pin Descriptions
1.4.1 V_DD and V_SS
Power is supplied to the MCU through V_DD and V_SS. V_DD is the power supply, V_SS is ground. The MCU
operates from a single 5-volt (nominal) power supply. Low-voltage devices in the E series operate at
3.0–5.5 volts.
Very fast signal transitions occur on the MCU pins. The short rise and fall times place high, short duration
current demands on the power supply. To prevent noise problems, provide good power supply bypassing
at the MCU. Also, use bypass capacitors that have good
high-frequency characteristics and situate them as close to the MCU as possible. Bypass requirements
vary, depending on how heavily the MCU pins are loaded.
VDD
VDD
2
IN
1
RESET
MC34(0/1)64
GND
3
4.7 kΩ
TO RESET
OF M68HC11
Figure 1-7. External Reset Circuit
VDD
VDD
VDD
MANUAL
RESET SWITCH
4.7 kΩ
4.7 k Ω
1.0 µF
IN
RESET
MC34164
GND
IN
RESET
MC34064
GND
4.7 kΩ
TO RESET
OF M68HC11
OPTIONAL POWER-ON DELAY AND MANUAL RESET SWITCH
Figure 1-8. External Reset Circuit with Delay
M68HC11E Family Data Sheet, Rev. 5.1
Freescale Semiconductor
21