z8f083a ZiLOG Semiconductor, z8f083a Datasheet - Page 163

• Manufacturer Part Number: z8f083a
• Description: High-performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

Crystal Oscillator
Operating Modes
Crystal Oscillator Operation
PS026308-1207
Note:
The products in the Z8 Encore! F083A Series contain an on-chip crystal oscillator for use
with external crystals with 32 kHz to 20 MHz frequencies. In addition, the oscillator
supports external RC networks with oscillation frequencies up to 4 MHz or ceramic
resonators with frequencies up to 8 MHz. The on-chip crystal oscillator is used to generate
the primary system clock for the internal eZ8 CPU and the majority of the on-chip
peripherals. Alternatively, the X
(32 kHz–20 MHz). If an external clock generator is used, the X
unconnected. The on-chip crystal oscillator also contains a clock filter function. For
details settings of this clock filter, see
filter is disabled and no divide to the input clock, namely the frequency of the signal on the
X
Although the XIN pin is used as an input for an external clock generator, the CLKIN pin is
better suited for such use. For more details, see
The Z8 Encore! F083A Series products support four OSCILLATOR modes.
•
•
•
•
The OSCILLATOR mode is selected using user-programmable Flash option bits. For
more details, see
The Flash option bit XTLDIS controls whether the crystal oscillator is enabled during
reset. The crystal may later be disabled after reset if a new oscillator has been selected as
the system clock. If the crystal is manually enabled after reset through the OSCCTL
register, the user code must wait at least 5000 IPO cycles for the crystal to stabilize. After
this, the crystal oscillator may be selected as the system clock.
Figure 22
external fundamental-mode, parallel-resonant crystal operating at 20 MHz. Recommended
20 MHz crystal specifications are provided in
IN
Minimum power for use with very low frequency crystals (32 kHz to 1 MHz).
Medium power for use with medium frequency crystals or ceramic resonators
(0.5 MHz to 8 MHz).
Maximum power for use with high frequency crystals (8 MHz to 20 MHz).
On-chip oscillator configured for use with external RC networks (<4 MHz).
input pin determines the frequency of the system clock in default settings.
on page 152 displays a recommended configuration for connection with an
Flash Option Bits
IN
input pin also accepts a CMOS-level clock input signal
on page 119.
Table 87
Table 96
on page 127. But by default, this clock
System Clock Selection
on page 152. Resistor R
Z8 Encore!
OUT
Product Specification
pin must be left
®
on page
F083A Series
Crystal Oscillator
1
is
145.
151