MT3170 MITEL [Mitel Networks Corporation], MT3170 Datasheet - Page 5

• Manufacturer Part Number: MT3170
• Description: Wide Dynamic Range DTMF Receiver
• Manufacturer: MITEL [Mitel Networks Corporation]

Note:
Resonator and Crystal Electric Equivalent Circuit
Oscillator
The MT327xB/337xB can be used in both external
clock or two pin oscillator mode. In two pin oscillator
mode,
connecting either a 4.194304 MHz crystal or ceramic
resonator
Specifications of the ceramic resonator and crystal
are tabulated in Table 4.
configure a number of these devices employing only
a single oscillator crystal. The OSC2 output of the
first device in the chain is connected to the OSC1
input of the next device. Subsequent devices are
connected similarily.
Table 4. Recommended Resonator and Crystal
Parameter
R1 = Equivalent resistor.
L1 = Equivalent inductance.
C1 = Equivalent compliance.
C0 = Capacitance between electrode.
COMPONENTS LIST:
C
X1 = Crystal or Resonator (4.194304 MHz)
Qm
R1
C1
C0
1
L1
= 0.1 F
Qm=quality factor of RLC model, i.e., 1/2
f
the
across
oscillator
10 %
Ohms
DTMF/CP Input
Unit
mH
pF
pF
%
Specifications
-
L1
OSC1
The oscillator circuit can also
circuit
Resonator
1.299E+03
34.890
±0.2%
6.580
0.359
4.441
C0
C1
It is also possible
and
is
Figure 3 - Application Circuit for MT327xB
X1
R1
completed
C1
OSC2
101.2E+ 03
15.1E-03
±0.01%
Crystal
95.355
12.0
R1C1.
25
MT3170B/71B, MT3270B/71B, MT3370B/71B
pins.
1
2
3
4
by
to
INPUT
OSC2
OSC1
V
SS
MT327xB
be driven by an 4.194304 MHz external clock applied
on pin OSC 1. The OSC2 pin should be left open.
For MT317xB
directly by an 4.194304 MHz external digital clock.
Applications
The circuit shown in Figure 3 illustrates the use of a
MT327xB in a typical receiver application. It requires
only a coupling capacitor (C1) and a crystal or
ceramic resonator (X1) to complete the circuit.
The MT3x70B is designed for user who wishes to
tailor the guard time for specific applications. When
a DTMF signal is present, the ESt pin will go high.
An external microcontroller monitors ESt in real time
for a period of time set by the user. A guard time
algorithm must be implemented such that DTMF
signals not meeting the timing requirements are
rejected. The MT3x71B uses an internal counter to
provide a preset DTMF validation period. It requires
no external components.
indicates that a valid DTMF digit has been detected.
The 4.194304 MHz frequency has a secondary
advantage in some applications where a real time
clock is required.
4,194,304 cycles to provide a one second time base.
ESt/DStD
ACK
V
SD
DD
8
7
6
5
devices , the CLK input is driven
A 22-bit counter will count
V
DD
To microprocessor or
microcontroller
The DStD output high
4-7