Datasheet

MT8870D/MT8870D-1 Data Sheet
5
Zarlink Semiconductor Inc.
The value of t
DP
is a device parameter (see Figure 11) 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.
Figure 5 - Guard Time Adjustment
Table 1 - Functional Decode Table
L=LOGIC LOW, H=LOGIC HIGH, Z=HIGH IMPEDANCE
X = DON‘T CARE
Digit TOE INH ESt Q
4
Q
3
Q
2
Q
1
ANYLXHZZZZ
1HXH0001
2HXH0010
3HXH0011
4HXH0100
5HXH0101
6HXH0110
7HXH0111
8HXH1000
9HXH1001
0HXH1010
*HXH1011
#HXH1100
AHLH1101
BHLH1110
CHLH1111
DHLH0000
AHHL
undetected, the output code
will remain the same as the
previous detected code
BHHL
CHHL
DHHL
V
DD
St/GT
ESt
C
1
R
1
R
2
a) decreasing t
GTP
; (t
GTP
<t
GTA
)
t
GTP
=(R
P
C
1
)In[V
DD
/(V
DD
-V
TSt
)]
t
GTA
=(R
1
C
1
)In(V
DD
/V
TSt
)
R
P
=(R
1
R
2
)/(R
1
+R
2
)
V
DD
St/GT
ESt
C
1
R
1
R
2
t
GTP
=(R
1
C
1
)In[V
DD
/(V
DD
-V
TSt
)]
t
GTA
=(R
P
C
1
)In(V
DD
/V
TSt
)
R
P
=(R
1
R
2
)/(R
1
+R
2
)
b) decreasing t
GTA
; (t
GTP
>t
GTA
)