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参数资料
| 型号： | M-88L70 |
| 厂商： | Clare, Inc. |
| 英文描述： | 3V DTMF Receiver |
| 中文描述： | 3V的双音多频接收器 |
| 文件页数： | 3/8页 |
| 文件大小： | 291K |
| 代理商： | M-88L70 |
M-88L70
www.clare.com
Rev. 1
3
ered a valid pause. This capability, together with the
ability to select the steering time constants externally,
allows the designer to tailor performance to meet a wide
variety of system requirements.
Guard Time Adjustment
Where independent selection of receive and pause are
not required, the simple steering circuit of Figure 3 is
applicable. Component values are chosen according to
the formula:
t
REC = tDP + tGTP
t
GTP @ 0.67 RC
The value of t
DP is a parameter of the device and tREC is
the minimum signal duration to be recognized by the
receiver. A value for C of 0.1
F is recommended for
most applications, leaving R to be selected by the
designer. For example, a suitable value of R for a t
REC of
40 ms would be 300 K ohm. A typical circuit using this
steering configuration is shown in Figure 4. The timing
requirements for most telecommunication applications
are satisfied with this circuit. Different steering arrange-
ments may be used to select independently the guard
times for tone-present (t
GTP) and tone-absent (tGTA). This
may be necessary to meet system specifications that
place both accept and reject limits on both tone duration
and interdigit pause.
Guard time adjustment also allows the designer to tailor
system parameters such as talkoff and noise immunity.
Increasing t
REC improves talkoff performance, since it
reduces the probability that tones simulated by speech
will maintain signal condition long enough to be regis-
tered. On the other hand, a relatively short t
REC with a
long t
DO would be appropriate for extremely noisy envi-
ronments where fast acquisition time and immunity to
dropouts would be required. Design information for
guard time adjustment is shown in Figure 5.
Input Configuration
The input arrangement of the M-88L70 provides a dif-
ferential input operational amplifier as well as a bias
source (V
REF) to bias the inputs at mid-rail. Provision is
made for connection of a feedback resistor to the op-
amp output (GS) for gain adjustment.
In a single-ended configuration, the input pins are con-
nected as shown in Figure 4 with the op-amp connect-
ed for unity gain and V
REF biasing the input at 1/2VDD.
Figure 7 shows the differential configuration, which per-
mits gain adjustment with the feedback resistor R5.
Figure 3 Basic Steering Circuit
F
LOW
F
HIGH
Key
OE
INH
ESt
Q4
Q3
Q2
Q1
(ref.)
ANY
L
X
H
Z
697
1209
1
H
X
H
0
1
697
1336
2
H
X
H
0
1
0
697
1477
3
H
X
H
0
1
770
1209
4
H
X
H
0
1
0
770
1336
5
H
X
H
0
1
0
1
770
1477
6
H
X
H
0
1
0
852
1209
7
H
X
H
0
1
852
1336
8
H
X
H
1
0
852
1477
9
H
X
H
1
0
1
941
1336
0
H
X
H
1
0
1
0
941
1209
*
H
X
H
1
0
1
941
1477
#
H
X
H
1
0
697
1633
A
H
L
H
1
0
1
770
1633
B
H
L
H
1
0
852
1633
C
H
L
H
1
941
1633
D
H
L
H
0
697
1633
A
H
L
Undetected, the output
770
1633
B
H
L
code will remain the
852
1633
C
H
L
same as the previous
941
1633
D
H
L
detected code.
L = logic low, H = logic high, Z = high impedance, X = don’t care
Table 2 Tone Decoding
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M-88L70-01P | 制造商:CLARE 制造商全称:Clare, Inc. 功能描述:3V DTMF Receiver |
| M-88L70-01S | 制造商:CLARE 制造商全称:Clare, Inc. 功能描述:3V DTMF Receiver |
| M-88L70-01T | 制造商:CLARE 制造商全称:Clare, Inc. 功能描述:3V DTMF Receiver |
| M88M88C | 制造商:MA-COM 制造商全称:M/A-COM Technology Solutions, Inc. 功能描述:TRIPLE-BALANCED MIXER |
| M88T | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:In-System Programmable ISP Multiple-Memory and Logic FLASHPSD Systems with CPLD for MCUs |
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