MSAN-101 Zarlink Semiconductor, Inc., MSAN-101 Datasheet - Page 8

• Manufacturer Part Number: MSAN-101
• Description: Applications of the MT8804A 8 x 4 Analog Switch Array
• Manufacturer: Zarlink Semiconductor, Inc.

control and minimizes external circuit requirements.
The 8 x 4 analog switch matrix configuration
provides
network design. All of these factors combine to make
the MT8804A an ideal basis for PBX and key system
networks.
Dual Tone Multifrequency Receiver
Tester Control Circuit
The versatility of the MT8804A is shown in the Dual
Tone Multifrequency (DTMF) receiver tester control
circuit of Figure 7. The high and low tones may be
mixed or a composite DTMF signal may be fed
directly to the receiver under test. By mixing either f
or f
twist may be added to the resulting DTMF signal.
The amount of twist may be varied by adjusting
resistor values. Dial tone rejection can be tested by
switching in the CM7065, Zarlink Corporation’s Precise
Dial Tone Generator. The series resistor (R
potentiometer are chosen to limit the voltage to the
MT8804A to the supply limits. Sensitivity to 60Hz can
be similarly tested.
If the receiver under test has the facility to accept
dial pulses, these may be generated by switching the
power supplies in and out at the required rates. A
single pole double throw relay R1, is added to
provide a switchable output impedance to simulate
long line conditions. The relay drive is also switched
by the MT8804A. The control of the MT8804A is
provided
A-24
H
through the 200K resistor, plus or minus 6dB of
great
by
a
flexibility
stored
in
test
Figure 7 - DTMF Receiver Tester Control Circuit
modular
program
switching
s
in
) and
a
L
microprocessor system or a hardwired controller
which dictates the sequence of input signals
presented to the receiver under test.
Test Equipment Switching System
Functional Description
The MT8804A is used as an analog coupling circuit
in this test equipment switching system application.
Various signal sources, voltmeters, a 2-channel
oscilloscope and a frequency counter are connected
to the multiplexer. (This section of course is
arbitrary). The test points of the circuit under test can
be connected to the multiplexer via banana plugs
and jacks, aligator clips or any appropriate means of
interconnection. This circuit can be very useful in
analyzing prototype circuits which require various
measurements at multiple test points.
The test instruments are connected to the test points
of the circuit under test through the MT8804A’s
shown in Fig. 8. The individual instruments are
selected by keys on the keypad as is the particular
test point to which this equipment is connected. The
system is operated as follows. First the ‘TEST
POINT’ switch is pressed, followed by one of the
numbered keys on the keypad. These correspond to
the test points. Next, a sequence of keys designated
the same as the test equipment is pressed. Finally
the ‘CONNECT’ button is pressed. This completes
the connection of the test equipment keyed in to the
selected test point. This procedure can be repeated