mc68hc05jb4p Freescale Semiconductor, Inc, mc68hc05jb4p Datasheet - Page 17

• Manufacturer Part Number: mc68hc05jb4p
• Description: Mc68hc705jb4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

frequency clock can be derived from a divided by 4 circuit. The type of oscillator is
selected by a mask option. An internal 2M
OSC1 and OSC2 by a mask option (crystal/ceramic resonator mode only).
Crystal Oscillator
The circuit in Figure 1-3 (a) shows a typical oscillator circuit for an AT-cut, parallel
resonant crystal. The crystal manufacturer’s recommendations should be fol-
lowed, as the crystal parameters determine the external component values
required to provide maximum stability and reliable start-up. 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 minimize output distortion. An internal start-up
resistor of approximately 2 M is provided between OSC1 and OSC2 for the crys-
tal type oscillator as a mask option.
Ceramic Resonator Oscillator
In cost-sensitive applications, a ceramic resonator can be used in place of the
crystal. The circuit in Figure 1-3 (a) can be used for a ceramic resonator. The res-
onator manufacturer’s recommendations should be followed, as the resonator
parameters determine the external component values required for maximum sta-
bility and reliable starting. The load capacitance values used in the oscillator cir-
cuit design should include all stray capacitances. The ceramic resonator and
components should be mounted as close as possible to the pins for start-up stabi-
lization and to minimize output distortion. An internal start-up resistor of approxi-
mately 2 M is provided between OSC1 and OSC2 for the ceramic resonator type
oscillator as a mask option.
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 Figure 1-3 (b).This
configuration is possible ONLY when the crystal/ceramic resonator mask option is
selected.
(a) Crystal or Ceramic Resonator Connections
OSC1
MCU
2M
Freescale Semiconductor, Inc.
For More Information On This Product,
Figure 1-3. Oscillator Connections
OSC2
Go to: www.freescale.com
resistor may be selected between
(b) External Clock Source Connection
OSC1
Unconnected
MCU
External Clock
OSC2