Zilog Z86193 - Manual (Page 37)

Z8
®
CPU
User Manual
UM001604-0108 Clock
30
Depending on operation frequency, the oscillator may require the addition of capacitors
C1 and C2 (displayed in
Figure 18 ). The capacitance values are dependent on the manu-
facturer’s crystal specifications.
In most cases, the R
D
is 0 Ω and R
F
is infinite. It is determined and specified by the crystal/
ceramic resonator manufacturer. The R
D
can be increased to decrease the amount of drive
from the oscillator output to the crystal. It can also be used as an adjustment to avoid clip-
ping of the oscillator signal to reduce noise. The R
F
can be used to improve the start-up of
the crystal/ceramic resonator. The Z8
®
oscillator already has an internal shunt resistor in
parallel to the crystal/ceramic resonator.
Figure 18. Crystal/Ceramic Resonator Oscillator
Figure 19. LC Clock
XTAL2
Z8
®
CPU
V
SS
XTAL1
C1 C2
R
F
R
D
XTAL2
Z8
®
CPU
V
SS
XTAL1
C1
C2
L