MT88E43
Vdd
TIP / A
Data Sheet
Vdd
R
4
MT88E43
1N4003
IN+
Vdd
60K4
1N4003
22nF
5%
R
1
1N4003
53K6
R
4
Vdd
464K
IN-
GS
V
Ref
CAP
Vdd
1N914
1N4003
22nF
5%
R
1
TISP4180,
TISP5180,
TPA150A12 or
TPB150B12
V
DD
St/GT
ESt
StD
INT
CD
DR
DATA
DCLK
FSKen
PWDN
IC
R
3
C
Vdd
100K
20%
1N914
RING / B
R
2
499K, 5%
100nF
1N914
5%
1N914
TRIGin
TRIGRC
TRIGout
MODE
150K
5%
499K, 5%
100nF
5%
200K
5%
301K
5%
220nF
100nF
OSCin
OSCout
V
SS
1N914
NOTE: Resistors must have 1% tolerance and capacitors have 20%
tolerance unless otherwise specified.
: Crystal is 3.579545MHz, 0.1% frequency tolerance.
: For BT Application C=0.1µF
±5%,
R
3
=422kΩ
±1%,
R
2
=422kΩ
±1%
:
For applications where CAS speech immunity is required (e.g. CIDCW)
C=0.1µF
±5%,
R
3
=825kΩ
±1%,
R
2
=226kΩ
±1%
: R
1
= 430K, R
4
= 34K for V
DD
= 5V
±
10% (See Figure 10)
: R
1
= 620K, R
4
= 63K4 for V
DD
= 3V
±
10% (See Figure 10)
= To microcontroller
= From microcontroller
(FSK Interface Mode 0 selected)
Figure 9 - Application Circuit
Application Circuits
The circuits shown in Figures 9 and 11 are
application circuits for the MT88E43. As supply
voltage (V
DD
) is decreased, the threshold of the
device’s tone and FSK detectors will be reduced.
Therefore, to meet the BT or Bellcore tone reject
level requirements the gain of the internal opamp
should be reduced according to the graph in Figure
10. For example when V
DD
=5V (+/- 10%), R
1
should
equal 430kΩ and R
4
should equal 34kΩ; and if
V
DD
=3V (+/- 10%) R
1
should equal 620kΩ and R
4
should equal 63.4kΩ. Resistors R
1
and R
4
are
shown in Figures 9 and 11.
The circuit shown in Figure 9 illustrates the use of the
MT88E43 in a proprietary system that doesn’t need to
meet FCC, DOC, and UL approvals. It should be noted
that if glitches on the tip/ring interface are of sufficient
amplitude, the circuit will falsely detect these signals as
ringing or line reversal.
The circuit shown in Figure 11 will provide common
mode rejection of signals received by the ringing circuit.
This circuit should pass safety related tests specified by
FCC Part 68, DOC CS-03, UL 1459, and CSA C22.2.
5-62
These safety tests will simulate high voltage faults that
may occur on the line. The circuit provides isolation
from these high voltage faults via R1 and the 12k1Ω re-
sistors as well as the 22nF & 330nF capacitors. IRC
manufactures a resistor (part number GS3) that should
be used for R1. This resistor is a 3W, 5%, 1kV power
resistor. The 12k1 resistor is manufactured by IRC (part
number FA8425F). This resistor is a 1.5W, 5%, fusea-
ble type resistor. The 22nF and 330nF capacitors have
a 400V rating.
See the application note "MSAN-164: Applications of
the MT8843 Calling Number Identification Circuit 2" for
information on designing the MT88E43 into CID and
CIDCW systems.
100nF
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
