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參數(shù)資料
| 型號(hào)： | HC5517IB |
| 廠商： | HARRIS SEMICONDUCTOR |
| 元件分類： | 模擬傳輸電路 |
| 英文描述： | GIGATRUE 550 CAT PATCH CBL NO BOOT 6FT RD 25 PK |
| 中文描述： | TELECOM-SLIC, PDSO28 |
| 文件頁(yè)數(shù)： | 13/18頁(yè) |
| 文件大?。?/td> | 175K |
| 代理商： | HC5517IB |
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72
Operation of the Battery Switch
The battery switch is used to select between the off-hook
battery of -24V and the ringing/standby battery of -80V.
When T
1
is off (battery switch is logic low) the MOSFET T
3
is off and the -24V battery is supplied to the SLIC through
D
10
. When T
1
is on (battery switch is logic high) current
flows through the collector of T
1
turning on the zener D
9
.
When D
9
turns on, the gate of the MOSFET is positive with
respect to the drain (-80V) and T
3
turns on. Turning T
3
on
connects the -80V battery to the SLIC through D
7
. This in
turn reverse biases D
10
, isolating the two supplies.
Transhybrid Balance
(Voice Signal)
The purpose of the transhybrid circuit is to remove the
receive signal (V-REC) from the transmit signal (V-XMIT),
thereby preventing an echo on the transmit side. This is
accomplished by using an external op amp (usually part of
the CODEC) and by the inversion of the signal from the
SLIC’s 4-wire receive port (V
RX
) to the SLIC’s 4-wire
transmit port (OUT1).
The external transhybrid circuit is shown in Figure 10. The
effects of capacitors C
5
, C
7
and C
8
are negligible and there-
fore omitted from the analysis. The input signal (V-REC) will
be subtracted from the output signal (V-XMIT) if I
1
equals I
2
are equal and opposite in phase. A node analysis yields the
following equation:
The value of R
2
is then:
Given that OUT1 is equal to -1/3 of V-REC (Equation 16) and
V-REC is equal to VTR (A
4-Wire-2-Wire
= 1, Equation 15),
then R
2
= 3R
3.
A transhybrid balance greater than 30dB can
be achieved by using 1% resistors values.
Transhybrid Balance
Transhybrid balance of the pulse metering signal is
accomplished in 2 stages. The first stage uses the SLIC’s
internal op amp to invert the phase of the pulse metering sig-
nal. The second stage sums the inverted pulse metering sig-
nal with the incoming signal for cancellation in the
transhybrid amplifier. A third network can be added to offset
both tip and ring by the peak amplitude of the pulse metering
signal. This will allow both the maximum voice and pulse
metering signals to occur at the same time with no distortion.
(Pulse Metering)
Pulse Metering
Pulse metering or Teletax is used outside the United States
for billing purposes at pay phones. A 12kHz or 16kHz burst
is injected into the 4-wire side of the SLIC and transmitted
across the tip and ring lines from the central office to the pay
phone. For more information about pulse metering than cov-
ered here reference application note AN9608 “Implementing
Pulse Metering for the HC5509 Series of SLICs”.
TABLE 2. HC5517 APPLICATION CIRCUIT OPERATING MODES SUMMARY
BATTERY
SWITCH
F1
RC
MODE
DETECTORS VALID
APPLICATION CIRCUIT VALID
SHD
RTD
MTU
CENTERING
-24V
0
0
Power Denial
-24V
0
1
Invalid
-24V
1
0
Off-Hook Active
√
-24V
1
1
Invalid
-80V
0
0
Power Denial
√
-80V
0
1
Invalid
-80V
1
0
On-Hook Standby
√
√
-80V
1
1
Ringing
(Note)
√
√
NOTE: During Ringing, the SHD output will be active for both on-hook and off-hook conditions. The AC current, for the on-hook condition, exceeds
the SHD threshold of 12mA. Valid off-hook detection during ringing is provided by the RTD output only.
–
2
--------------------
3
----------------
+
0
=
(EQ. 36)
R
2
R
–
3
–
--------------------
=
(EQ. 37)
FIGURE 10. TRANSHYBRID CIRCUIT (VOICE SIGNAL)
EXTERNAL
TRANSHYBRID CIRCUIT
SUMMING NODE CANCELS OUT
INCOMING AC TRANSMISSION FROM
OUT GOING TRANSMISSION
R
2
R
1
R
3
INCOMING
AC TRANSMISSION
V
RX
180
PHASE
SHIFT
OF AC
SIGNAL
-IN1
OUT1
R
9
R
8
V-XMIT
C
8
C
7
C
5
I
1
I
2
V-REC
HC5517
OUTGOING
AC TRANSMISSION
+
-
+
-
HC5517
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| HC5517IM | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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| HC55180 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Extended Reach Ringing SLIC Family |
| HC55180_05 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Extended Reach Ringing SLIC Family |
| HC55180CIM | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
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