Z8E001 Datasheet, PDF (25/49 Pages) Zilog, Inc. – CMOS OTP Microcontroller

Zilog
Crystals and Resonators
Crystals and ceramic resonators (Figure 15) should have
the following characteristics to ensure proper oscillator op-
eration:
Crystal Cut
Mode
Crystal Capacitance
Load Capacitance
Resistance
AT (crystal only)
Parallel, Fundamental Mode
<7pF
10pF < CL < 220 pF,
15 typical
100 ohms max
Depending on operation frequency, the oscillator may re-
quire the addition of capacitors C1 and C2 (shown in Fig-
ures 15 and16). The capacitance values are dependent on
the manufacturer’s crystal specifications.
XTAL1
V_SS
Z8E001
XTAL2
R_F
R_D
C1
C2
Figure 17. Crystal/Ceramic Resonator Oscillator
Z8E001
CMOS OTP Microcontroller
In most cases, the R_D is 0 Ohms and R_F is infinite. It is de-
termined 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 clipping of the
oscillator signal to reduce noise. The R_F can be used to im-
prove the start-up of the crystal/ceramic resonator. The
Z8E001 oscillator already has an internal shunt resistor in
parallel to the crystal/ceramic resonator.
XTAL1
Z8E001
V_SS
N/C
XTAL2
Figure 19. External Clock
It is recommended in Figures 14, 15, and 16 to connect the
load capacitor ground trace directly to the V_SS (GND) pin
of the Z8E001. This ensures that no system noise is inject-
ed into the Z8E001 clock. This trace should not be shared
with any other components except at the V_SS pin of the
Z8E001.
Please note that a parallel resonant crystal or resonator
data sheet will specify a load capacitor value that is the se-
ries combination of C₁ and C₂, including all parasitics (PCB
and holder).
XTAL1
C1
L Z8E001
V_SS
XTAL2
C2
Figure 18. LC Clock
DS97Z8X1300
PRELIMINARY
25