MC705P6A Motorola, MC705P6A Datasheet - Page 15

• Manufacturer Part Number: MC705P6A
• Description: Microcontrollers
• Manufacturer: Motorola

1.3 Functional Pin Description
The following paragraphs describe the functionality of each pin on the MC68HC705P6A package. Pins
connected to subsystems described in other chapters provide a reference to the chapter instead of a
detailed functional description.
1.3.1 V
Power is supplied to the MCU through V
V
Very fast signal transitions occur on the MCU pins. The short rise and fall times place very 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. Use bypass capacitors with good high-frequency
characteristics and position them as close to the MCU as possible. Bypassing requirements vary,
depending on how heavily the MCU pins are loaded.
1.3.2 OSC1 and OSC2
The OSC1 and OSC2 pins are the control connections for the on-chip oscillator. The OSC1 and OSC2
pins can accept the following:
The frequency, f
clock operating frequency, f
is clear when a STOP instruction is executed.
Freescale Semiconductor
SS
1. A crystal as shown in
2. A ceramic resonator as shown in
3. An external clock signal as shown in
is connected to ground.
DD
and V
osc
SS
, of the oscillator or external clock source is divided by two to produce the internal bus
(a)
To V
OSC1
37 pF
DD
Crystal or Ceramic
Resonator Connections
(or STOP)
MC68HC705P6A Advance Information Data Sheet, Rev. 2.1
op
4.7 MΩ
Figure
. The oscillator cannot be turned off by software unless the MOR bit, SWAIT,
Figure 1-2. Oscillator Connections
1-2(a)
OSC2
37 pF
DD
Figure
MCU
and V
Figure
1-2(a)
SS
1-2(b)
. V
DD
is connected to a regulated +5 volt supply and
To V
(b)
OSC1
DD
(or STOP)
External Clock Source
Connections
UNCONNECTED
EXTERNAL CLOCK
OSC2
MCU
Functional Pin Description
15