mc68hc05x4dw Freescale Semiconductor, Inc, mc68hc05x4dw Datasheet - Page 24

• Manufacturer Part Number: mc68hc05x4dw
• Description: Xc68hc705x4 Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

MDS/TCAP(VPP)
OSC1/OSC2
System clocks
Crystal
Modes of Operation and Pin Descriptions
MC68HC05X4 Rev 1.0
OSC1
f
osc
During reset this pin is used as a mode select input (MDS) to determine
the operating mode. It also serves as the input capture (TCAP) pin for
the 16-bit programmable timer. In addition it is the EPROM programming
voltage input pin (VPP) for the MC68HC705X4 device.
These pins provide control input for an on-chip clock oscillator circuit. A
crystal, ceramic resonator or external clock signal connected to these
pins provides the oscillator clock. The oscillator frequency (f
divided by 2 or by 10, chosen via a mask option, to provide the internal
bus frequency (f
The MCU and MCAN system clocks are obtained as shown in the
Figure
The circuit shown in
The internal oscillator is designed to interface with an AT-cut
parallel-resonant quartz crystal resonator in the frequency range
specified for f osc (refer to
external CMOS oscillator is recommended when crystals outside the
specified ranges are to be used. The crystal and components should be
mounted as close as possible to the input pins to minimise output
distortion and start-up stabilization time.
Divide by
Divide by
10 or 2
Freescale Semiconductor, Inc.
2
For More Information On This Product,
Figure 7. Oscillator block diagram
Modes of Operation and Pin Descriptions
7.
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f
f
MCU bus clock
OP
osc
OP
/2
).
Figure
DC electrical
8(a) is recommended when using a crystal.
Prescaler (P)
characteristics). Use of an
MCAN module system clock
t
SCL
=
OSC
f
2P
osc
) is
12-modes