MT88L70
Data Sheet
the steering time constants externally, allows the designer to tailor performance to meet a wide variety of system
requirements.
Digit
ANY
1
2
3
4
5
6
7
8
9
0
*
#
A
B
C
D
A
B
C
D
TOE
L
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
INH
X
X
X
X
X
X
X
X
X
X
X
X
X
L
L
L
L
H
H
H
H
ESt
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
H
L
L
L
L
Q
4
Z
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
Q
3
Z
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
Q
2
Z
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
Q
1
Z
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
undetected, the output code
will remain the same as the
previous detected code
Table 1 - Functional Decode Table
L=LOGIC LOW, H=LOGIC HIGH, Z=HIGH IMPEDANCE
X = DON‘T CARE
Guard Time Adjustment
In many situations not requiring selection of tone duration and interdigital pause, the simple steering circuit shown
in Figure 3 is applicable. Component values are chosen according to the formula:
t
REC
=t
DP
+t
GTP
t
ID
=t
DA
+t
GTA
The value of t
DP
is a device parameter (see Figure 7) and t
REC
is the minimum signal duration to be recognized by
the receiver. A value for C of 0.1
µF
is recommended for most applications, leaving R to be selected by the
designer.
4
Zarlink Semiconductor Inc.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
