參數(shù)資料
型號： MT8870D-1
廠商： Mitel Networks Corporation
英文描述： Integrated DTMF Receiver(完全雙音多頻信號（DTMF）接收器（集成了濾波器和數(shù)字譯碼器功能）)
中文描述： 集成雙音多頻接收器（完全雙音多頻信號（DTMF）的接收器（集成了濾波器和數(shù)字譯碼器功能））
文件頁數(shù)： 4/17頁
文件大?。?/td> 137K
代理商： MT8870D-1
MT8870D/MT8870D-1
ISO
2
-CMOS
4-14
condition is maintained (ESt remains high) for the
validation period (t
GTP
), v
c
reaches the threshold
(V
TSt
) of the steering logic to register the tone pair,
latching its corresponding 4-bit code (see Table 1)
into the output latch. At this point the GT output is
activated and drives v
c
to V
DD
. GT continues to drive
high as long as ESt remains high. Finally, after a
short delay to allow the output latch to settle, the
delayed steering output flag (StD) goes high,
signalling that a received tone pair has been
registered. The contents of the output latch are
made available on the 4-bit output bus by raising the
three state control input (TOE) to a logic high. The
steering circuit works in reverse to validate the
interdigit pause between signals. Thus, as well as
rejecting signals too short to be considered valid, the
receiver will tolerate signal interruptions (dropout)
too short to be considered a valid pause. This facility,
together with the capability of selecting the steering
time constants externally, allows the designer to
tailor performance to meet a wide variety of system
requirements.
Guard Time Adjustment
In many situations not requiring selection of tone
duration and interdigital pause, the simple steering
circuit shown in Figure 4 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
11) and t
REC
is the minimum signal duration to be
recognized by the receiver. A value for C of 0.1
μ
F is
Figure 5 - Guard Time Adjustment
Table 1. Functional Decode Table
L=LOGIC LOW, H=LOGIC HIGH, Z=HIGH IMPEDANCE
X = DON‘T CARE
recommended for most applications, leaving R to be
selected by the designer.
Different steering arrangements may be used to
select independently the guard times for tone
present (t
GTP
) and tone absent (t
GTA
). This may be
necessary to meet system specifications which place
both accept and reject limits on both tone duration
and interdigital pause. Guard time adjustment also
allows the designer to tailor system parameters
such as talk off and noise immunity. Increasing t
REC
improves talk-off performance since it reduces the
probability that tones simulated by speech will
maintain signal condition long enough to be
registered. Alternatively, a relatively short t
REC
with
a long t
DO
would be appropriate for extremely noisy
environments where fast acquisition time and
immunity to tone drop-outs are required. Design
information for guard time adjustment is shown in
Figure 5.
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
)
Digit
TOE
INH
ESt
Q
4
Z
Q
3
Z
Q
2
Z
Q
1
Z
ANY
L
X
H
1
H
X
H
0
0
0
1
2
H
X
H
0
0
1
0
3
H
X
H
0
0
1
1
4
H
X
H
0
1
0
0
5
H
X
H
0
1
0
1
6
H
X
H
0
1
1
0
7
H
X
H
0
1
1
1
8
H
X
H
1
0
0
0
9
H
X
H
1
0
0
1
0
H
X
H
1
0
1
0
*
H
X
H
1
0
1
1
#
H
X
H
1
1
0
0
A
H
L
H
1
1
0
1
B
H
L
H
1
1
1
0
C
H
L
H
1
1
1
1
D
H
L
H
0
0
0
0
A
H
H
L
undetected, the output code
will remain the same as the
previous detected code
B
H
H
L
C
H
H
L
D
H
H
L
相關(guān)PDF資料
PDF描述
MT8870 ()
MT8880C ISO2-CMOS Integrated DTMFTransceiver
MT8880CE-1 ISO2-CMOS Integrated DTMFTransceiver
MT8880CC ISO2-CMOS Integrated DTMFTransceiver
MT8880CE ISO2-CMOS Integrated DTMFTransceiver
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MT8870DC 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Integrated DTMF Receiver
MT8870DC-1 制造商:MITEL 制造商全稱:Mitel Networks Corporation 功能描述:ISO2-CMOS Integrated DTMF Receiver
MT8870DE 制造商:Microsemi Corporation 功能描述:
MT8870DE1 制造商:Microsemi Corporation 功能描述:DTMF RX 3.58MHZ CMOS 5V 18PDIP - Rail/Tube 制造商:Microsemi Corporation 功能描述:Pb Free DTMF RECEIVER DIP 制造商:Zarlink Semiconductor Inc 功能描述:DTMF RX 3.58MHZ CMOS 5V 18PDIP - Rail/Tube 制造商:Zarlink Semiconductor Inc 功能描述:Pb Free DTMF RECEIVER DIP
MT8870DE-1 制造商:Microsemi Corporation 功能描述:DTMF RX 3.58MHZ CMOS 5V 18PDIP - Rail/Tube 制造商: 功能描述: 制造商:undefined 功能描述:
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