mc68hc05l25 Freescale Semiconductor, Inc, mc68hc05l25 Datasheet - Page 21

• Manufacturer Part Number: mc68hc05l25
• Description: M68hc05 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

1.5.4.1 Crystal or Ceramic Resonator
The circuit in
The crystal manufacturer’s recommendations should be followed, since the crystal parameters determine
the external component values required to provide maximum stability and reliable startup. The load
capacitance values used in the oscillator circuit design should include all stray capacitances. The crystal
and components should be mounted as close as possible to the pins for startup stabilization and to
minimize output distortion. An internal startup feedback resistor of R
selected as a mask option.
1.5.4.2 External Clock
An external clock from another CMOS-compatible device can be connected to the OSC1 input, with the
OSC2 output not connected, as shown in
oscillator setup.
1.5.5 XOSC1 and XOSC2
The XOSC1 and XOSC2 pins are the connections for the 2-pin on-chip oscillator. The XOSC1 and
XOSC2 pins can accept these sets of components:
The frequency, f
operating frequency, f
1.5.5.1 Crystal
The circuit in
crystal manufacturer’s recommendations should be followed, since the crystal parameters determine the
external component values required to provide maximum stability and reliable startup. The load
capacitance values used in the oscillator circuit design should include all stray capacitances. The crystal
and components should be mounted as close as possible to the pins for start-up stabilization and to
Freescale Semiconductor
1. A crystal as shown in
2. An external clock signal as shown in
Figure
Figure
XOSC
MASK OPTION
1-4(a) shows a typical 2-pin oscillator circuit for an AT-cut, parallel, resonant crystal.
1-5(a) shows a typical 2-pin oscillator circuit for a 32.768-kHz “watch” crystal. The
, of the oscillator or external clock source is divided by two to produce the internal
OP
, if selected by SYS1:SYS0 bits.
Figure
(a) Crystal Connections
Figure 1-5. Oscillator Connections
1-5(a)
XOSC1
32.768 kHz (TYP)
MC68HC05L25 Data Sheet, Rev. 3.1
C
XO1
MCU
R
XOF
Figure
XOSC2
C
Figure
R
XO2
XOD
1-4(b). This configuration is possible regardless of the
1-5(b)
OF
XOSC1
Source Connection
(b) External Clock
between OSC1 and OSC2 can be
EXTERNAL CLOCK
MCU
UNCONNECTED
XOSC2
Functional Pin Description
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