Z16C3516VSG Zilog, Z16C3516VSG Datasheet - Page 249

• 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

UM011001-0601
However, there are several ranges of frequencies where
the reactance is positive; these are the fundamental
(desired frequency of operation), and the third and fifth
mechanical overtones (approximately 3 and 5 times the
fundamental frequency). Since the desired frequency
range in this application is always the fundamental, the
overtones must be suppressed. This is done by reducing
the loop gain at these frequencies. Usually, the amplifier’s
gain roll off, in combination with the crystal parasitics and
load capacitors, is sufficient to reduce gain and prevent
oscillation at the overtone frequencies.
The following parameters are for an equivalent circuit of a
quartz crystal (Figure 4):
L - motional inductance (typ 120 mH @ 4 MHz)
C - motional capacitance (typ .01 pf @ 4 MHz)
R - motional resistance (typ 36 ohm @ 4 MHz)
Cs - shunt capacitance resulting from the sum of the
capacitor formed by the electrodes (with the quartz as a
dielectric) and the parasitics of the contact wires and
holder (typ 3 pf @ 4 MHz).
The series resonant frequency is given by:
* fs - fp is very small (approximately 300 parts per million)
Z
0
Figure 3. Series vs. Parallel Resonance
CAPACITIVE
INDUCTIVE
Region of Parallel
Operation
Fs = 1/(2 x sqrt of LC),
Thus, they cancel each other and the crystal is then R
shunted by Cs with zero phase shift.
The parallel resonant frequency is given by:
Fp = 1/[2 x sqrt of L (C Ct/C+Ct)],
where Xc and Xl are equal.
where: Ct = C
fs
fp*
Figure 4. Quartz Oscillator
Symbolic Representation
Quartz Equivalent Circuit
L
R
+ C
S
Cs
L
On-Chip Oscillator Design
2
C
Application Note
15-3
1