MC68HC05X4 Datasheet, PDF (25/156 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Ceramic
resonator
External clock
Freescale Semiconductor, Inc.
Modes of Operation and Pin Descriptions
Pin descriptions
A ceramic resonator may be used instead of the crystal in cost-sensitive
applications. The circuit in Figure 8(a) is recommended when using a
ceramic resonator. The manufacturer of the particular ceramic resonator
being considered should be consulted for specific information. This
option is recommended only for applications that operate at an external
clock frequency of 8MHz or less. Any application requiring an external
operating frequency greater that 8MHz should use either a crystal
oscillator or an external CMOS compatible clock source.
An external clock should be applied to the OSC1 input with the OSC2 pin
not connected, as shown in Figure 8(c). The t_OXOV specification does not
apply when using an external clock input. The equivalent specification of
the external clock source should be used in lieu of t_OXOV.
OSC1
L
C₁
R_S
OSC2
MCU
OSC1
OSC2
C_OSC1
C_OSC2
(a) Crystal/ceramic resonator
oscillator connections
C₀
(b) Crystal equivalent circuit
MCU
OSC1
OSC2
13-modes
MOTOROLA
External
NC
clock
(c) External clock source connections
Figure 8. Oscillator connections
Modes of Operation and Pin Descriptions
For More Information On This Product,
Go to: www.freescale.com
MC68HC05X4 Rev 1.0
25