Z16C3516VSG Zilog, Z16C3516VSG Datasheet - Page 250

• Manufacturer Part Number: Z16C3516VSG
• Description: IC 16MHZ Z8500 CMOS ISCC 68-PLCC
• Manufacturer: Zilog
• Series: IUSC™r

Specifications of Z16C3516VSG

• Controller Type: Serial Communications Controller (SCC)
• Interface: USB
• Voltage - Supply: 4.75 V ~ 5.25 V
• Current - Supply: 50mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 68-LCC (J-Lead)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 269-4690-5; Z16C3516VSG

Application Note
On-Chip Oscillator Design
Series vs. Parallel Resonance.
difference between series and parallel resonance
frequencies (Figure 3). A series resonant crystal
(operating at zero phase shift) is desired for non-inverting
amplifiers. A parallel resonant crystal (operating at or near
180 degrees of phase shift) is desired for inverting amps.
Figure 3 shows that the difference between these two
operating modes is small. Actually, all crystals have
operating points in both serial and parallel modes. A series
resonant circuit will NOT have load caps C1 and C2. A
data sheet for a crystal designed for series operation does
not have a load cap spec. A parallel resonant crystal data
sheet specifies a load cap value which is the series
combination of C1 and C2. For this App Note discussion,
since all the circuits of interest are inverting amplifier
based, only the parallel mode of operation is considered.
15-4
OSCILLATOR THEORY OF OPERATION (Continued)
Impedance
(Ohm
100000
10000
1000
100
10
1
0
There is very little
Figure 5. Ceramic Resonator Reactance
2000
4000
Ceramic Resonators
Ceramic resonators are similar to quartz crystals, but are
used where frequency stability is less critical and low cost
is desired. They operate on the same basic principle as
quartz crystals as they are piezoelectric devices and have
a similar equivalent circuit. The frequency tolerance is
wider (0.3 to 3%), but the ceramic costs less than quartz.
Figure 5 shows reactance vs. frequency and Figure 6
shows the equivalent circuit.
Typical values of parameters are L = .092 mH, C = 4.6 pf,
R = 7 ohms and Cs = 40 pf, all at 8 MHz. Generally,
ceramic resonators tend to start up faster but have looser
frequency tolerance than quartz. This means that external
circuit parameters are more critical with resonators.
6000
8000
Frequency (KHz)
UM011001-0601
10000