- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄359232 > MT88E43AE (ZARLINK SEMICONDUCTOR INC) Extended Voltage Calling Number Identification Circuit 2 PDF資料下載
參數(shù)資料
| 型號： | MT88E43AE |
| 廠商： | ZARLINK SEMICONDUCTOR INC |
| 元件分類： | 無繩電話/電話 |
| 英文描述： | Extended Voltage Calling Number Identification Circuit 2 |
| 中文描述： | TELEPHONE CALLING NO IDENT CKT, PDIP24 |
| 封裝： | 0.600 INCH, PLASTIC, DIP-24 |
| 文件頁數(shù)： | 6/26頁 |
| 文件大小： | 317K |
| 代理商： | MT88E43AE |
第1頁第2頁第3頁第4頁第5頁當(dāng)前第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁
MT88E43
Preliminary Information
5-58
Dual Tone Detection Guard Time
When the dual tone alert signal is detected by the
MT88E43, ESt goes high. When the alerting signal
ceases to be detected, ESt goes low.
The ESt pin signals raw detection of CAS/Alerting
Tones. Since both Bellcore and BT applications
require a minimum duration for valid signals, ESt
detection must be guard time qualified. The StD pin
provides guard time qualified CAS/Alerting Tone
detection. When the MT88E43 is used in a caller
identity system, StD indicates correct CAS/Alerting
Tone detection.
Figure 4 shows the relationship between the St/GT,
ESt and StD pins. It also shows the operation of a
guard time circuit.
The total recognition time is t
REC
= t
GP
+ t
DP
, where
t
GP
is the tone present guard time and t
DP
is the tone
present detect time (refer to timing between ESt, St/
GT and StD in Figures 17 and 20).
The total tone absent time is t
ABS
= t
GA
+ t
DA
, where
t
GA
is the tone absent guard time and t
DA
is the tone
absent detect time (refer to timing between ESt, St/
GT and StD in Figures 17 and 20).
Bellcore states that it is desirable to be able to turn
off CAS detection for an off-hook capable CPE. The
disable
switch
allows
disconnects a service that relies on CAS detection
(e.g., CIDCW) but retains the CPE, to turn off the
detector and not be bothered by false detection.
the
subscriber
who
When SW1 in Figure 4 is in the B position the guard
time circuit is disabled. The detector will still process
CAS/Alerting tones but the MT88E43 will not signal
their presence by ensuring StD is low.
BT specifies that the idle state tone alert signal
recognition time should not be less than 20ms when
both tones are used for detection. That is, both tones
must be detected together for at least 20ms before
the signal can be declared valid. This requirement
can be met by setting the t
GP
(refer to Figure 5) to at
least 20ms.
BT also specifies that the TE is required to apply a
D.C. wetting pulse and an AC load 15-25ms after the
end of the alerting signal. If t
ABS
=t
DA
+t
GA
is 15 to
25ms, the D.C. current wetting pulse and the A.C.
load can both be applied at the falling edge of StD.
The maximum
t
DA
is 8ms so t
GA
should be 15-17ms.
Therefore, t
GP
must be greater than t
GA
. Figure 5(a)
shows a possible implementation. The values in
Figures 9 and 11 (R2=R3=422K, C=0.1
μ
F) will meet
the BT timing requirements.
Figure 4 - Guard Time Circuit Operation
Figure 5 - Guard Time Circuits with
Unequal Times
Input Configuration
The MT88E43 provides an input arrangement
comprised of an operational amplifier and a bias
source (V
Ref
); which is used to bias the opamp inputs
at V
DD
/2
. The feedback resistor at the opamp output
(GS) can be used to adjust the gain. In a single-
ended configuration, the opamp is connected as
shown in Figure 6. For a differential input
configuration, Figure 7 shows the necessary
connections.
+
-
V
ESt
St/GT
V
DD
StD
= V
SS
Tones detected
From
detector
C
R
Q1
Q2
MT88E43
Comparator
P
N
V
SS
SW1
B
A
(b) t
GP
< t
GA
t
GP
= R
P
C ln [V
DD
-V
D
(R
P
/R2))/(V
DD
-V
TGt
-V
D
(R
P
/R2))]
t
GA
= R1C ln (V
DD
/V
TGt
)
R
P
= R1R2/(R1+R2)
(a) t
GP
> t
GA
t
GP
= R1C ln [V
DD
/(V
DD
-V
TGt
)]
t
GA
= R
P
C ln [(V
DD
-V
D
(R
P
/R2))/(V
TGt
-V
D
(R
P
/R2))]
R
P
= R1R2/(R1+R2)
MT88E43
V
DD
St/GT
ESt
R1
R2
C
V
D
=diode forward voltage
V
DD
St/GT
ESt
R1
R2
C
V
D
=diode forward voltage
MT88E43
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MT88E43AS | Extended Voltage Calling Number Identification Circuit 2 |
| MT88E45B | 4-Wire Calling Number Identification Circuit 2 |
| MT88E45BN | 4-Wire Calling Number Identification Circuit 2 |
| MT88E45BS | 4-Wire Calling Number Identification Circuit 2 |
| MT88E46 | Bellcore Compliant Calling Number Identification Circuit |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MT88E43AS | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:Extended Voltage Calling Number Identification Circuit 2 |
| MT88E43B | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:Extended Voltage Calling Number Identification Circuit 2 |
| MT88E43BE | 制造商:ZARLINK 制造商全稱:Zarlink Semiconductor Inc 功能描述:Extended Voltage Calling Number Identification Circuit 2 |
| MT88E43BS | 制造商:Microsemi Corporation 功能描述: |
| MT88E43BS1 | 制造商:Microsemi Corporation 功能描述:CALLER ID CMOS 3.58MHZ 3.3V/5V 24SOIC - Rail/Tube 制造商:Microsemi Corporation 功能描述:CALLING NUMBER ID CIRCUIT 2 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。