MT88E43B
Crystal Oscillator
The MT88E43 requires a 3.579545MHz crystal oscillator as the master timing source.
Data Sheet
MT88E43
OSC1
OSC2
MT88E43
OSC1
OSC2
MT88E43
OSC1
OSC2
3.579545 MHz
to the
next MT88E43
Figure 8 - Common Crystal Connection
The crystal specification is as follows:
Frequency:
Frequency tolerance:
Resonance mode:
Load capacitance:
Maximum series resistance:
Maximum drive level (mW):
e.g., CTS MP036S
3.579545 MHz
±0.1%(-40
o
C+85
o
C)
Parallel
18 pF
150 ohms
2 mW
Any number of MT88E43 devices can be connected as shown in Figure 8 such that only one crystal is required.
The connection between OSC2 and OSC1
can be D.C. coupled as shown, or the OSC1 input on all devices can be driven from a CMOS buffer (dc coupled)
with the OSC2 outputs left unconnected.
To meet BT and Bellcore requirements for proper tone detection the crystal must have a frequency tolerance of
0.1%.
VRef and CAP Inputs
V
Ref
is the output of a low impedance voltage source equal to V
DD/2
and is used to bias the input opamp. A 0.1µF
capacitor is required between CAP and V
SS
to eliminate noise on V
Ref.
12
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
