z8f1621 ZiLOG Semiconductor, z8f1621 Datasheet - Page 221

• Manufacturer Part Number: z8f1621
• Description: High Performance 8-bit Microcontrollers
• Manufacturer: ZiLOG Semiconductor

On-Chip Oscillator
Operating Modes
Crystal Oscillator Operation
PS019921-0308
The products in the Z8 Encore! XP
with external crystals with frequencies from 32 kHz to 20 MHz. In addition, the oscillator
can support external RC networks with oscillation frequencies up to 4 MHz or ceramic
resonators with oscillation frequencies up to 20 MHz. This oscillator generates the pri-
mary system clock for the internal eZ8
Alternatively, the X
20 MHz). If an external clock generator is used, the X
When configured for use with crystal oscillators or external clock drivers, the frequency of
the signal on the X
internal clock divider). In RC operation, the system clock is driven by a clock divider
(divide by 2) to ensure 50% duty cycle.
The Z8 Encore! XP F64XX Series products support four different oscillator modes:
•
•
•
•
The oscillator mode is selected through user-programmable Option Bits. For more infor-
mation, see
Figure 39
external fundamental-mode, parallel-resonant crystal operating at 20 MHz. Recommended
20 MHz crystal specifications are provided in
optional and limits total power dissipation by the crystal. The printed circuit board layout
must add no more than 4 pF of stray capacitance to either the X
tion does not occur, reduce the values of capacitors C1 and C2 to decrease loading.
On-chip oscillator configured for use with external RC networks (<4 MHz).
Minimum power for use with very low frequency crystals (32 kHz to 1.0 MHz).
Medium power for use with medium frequency crystals or ceramic resonators
(0.5 MHz to 10.0 MHz).
Maximum power for use with high frequency crystals or ceramic resonators
(8.0 MHz to 20.0 MHz).
on page 208 displays a recommended configuration for connection with an
Option Bits
IN
IN
input pin determines the frequency of the system clock (that is, no
input pin can also accept a CMOS-level clock input signal (32 kHz–
on page 191.
®
F64XX Series feature an on-chip oscillator for use
™
CPU and the majority of the on-chip peripherals.
Table 104
OUT
Z8 Encore! XP
on page 208. Resistor R1 is
pin must be left unconnected.
IN
Product Specification
or X
OUT
®
On-Chip Oscillator
F64XX Series
pins. If oscilla-
207