MCMC68HC05L16 Freescale Semiconductor, Inc, MCMC68HC05L16 Datasheet - Page 18

• Manufacturer Part Number: MCMC68HC05L16
• Description: M68hc05 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

General Description
1.5.2.2 External Clock
An external clock from another CMOS-compatible device can be connected to the OSC1 input, with the
OSC2 input not connected, as shown in
oscillator is set up.
1.5.3 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:
The frequency, f
operating frequency, f
When XOSC is not used, the XOSC1 pin must be connected to the RESET pin to ensure proper
initialization of the clock circuitry. XOSC2 pin should remain unconnected.
1.5.3.1 Crystal Resonator
The circuit in
The crystal manufacturer’s recommendations should be followed, as 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
and a damping resistor of R
resistor value is 15 MΩ, and R
18
•
•
A crystal as shown in
An external clock signal as shown in
Figure
MASK OPTIONS
OSC
, of the oscillator or external clock source is divided by two to produce the internal
1-4(a) shows a typical 2-pin oscillator circuit for an AT-cut, parallel resonant crystal.
OP
, if selected by SYS1–SYS0 bits.
XOD
(a) Crystal Connections
Figure
MC68HC05L16 • MC68HC705L16 Data Sheet, Rev. 4.1
XOD
in series to XOSC2 may be selected as a mask option. Typical R
Figure 1-4. Oscillator Connections
resistor value is 1 MΩ.
1-4(a)
XOSC1
32.768 kHz (TYP)
C
XO1
Figure
MCU
R
XOF
R
XOD
Figure
C
XOSC2
XO2
1-3. This configuration is possible regardless of how the
1-4(b)
XOSC1
XOF
Source Connection
(b) External Clock
between XOSC1 and XOSC2
UNCONNECTED
EXTERNAL CLOCK
MCU
XOSC2
Freescale Semiconductor
XOF