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參數資料
| 型號： | L9217A |
| 英文描述： | CAP CER 2700PF 3.15KVDC R3 RAD |
| 中文描述： | 低成本線接口，具有反向電池和PPM |
| 文件頁數： | 22/30頁 |
| 文件大小： | 414K |
| 代理商： | L9217A |
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22
Agere Systems Inc.
Data Sheet
November 2001
with Reverse Battery and PPM
L9217A/G Low-Cost Line Interface
Applications
(continued)
Periodic Pulse Metering (PPM)
Periodic pulse metering (PPM), also referred to as
TTX, is input to the PPMIN input of the L9217. Upon
application of appropriate logic control, this signal is
presented to the tip/ring subscriber loop. The state of
the L9217 may be changed while applying PPM sig-
nals. The L9217 assumes that a shaped PPM signal is
applied to the PPMIN input.
Sufficient drive current is available in the tip and ring
drive amplifiers to support 3.5 Vrms PPM signals into a
200
load with a 45 mA dc current limit.
PPM signals are input to a separate PPMIN input. This
input is controlled via the logic table. PPMIN is off dur-
ing all states except the forward/reverse PPM active
state. Thus, PPM signals may be present at all times,
even during non-PPM active times. To apply PPM to
tip/ring, from a normal overhead state first switch to a
high overhead state without PPM; the overhead volt-
age at tip/ring will increase to 7 V to 13 V. The ramp up
time of the overhead increase is on the order of hun-
dreds of milliseconds. Thus, wait 1 s before applying
the PPM signal by going to a PPM active high over-
head state. Once in a high overhead, there is no timing
requirement in switching in and out of a PPM active
mode. Without the initial 1 s delay, AT/AR will get into
saturation and PPM signal at T/R will get distorted, pro-
ducing crosstalk in the handset.
PPM input signals may be a maximum 0.525 Vrms at
PPMIN. The gain from PPMIN tip/ring is 10. Thus, for
2.5 Vrms at tip and ring, apply a 0.375 Vrms signal at
PPMIN. The PPM signal should be ac coupled to
PPMIN through a 0.01
μ
F capacitor.
When applied to tip and ring, the PPM signal will also
be returned through the SLIC and will appear at the
SLIC VITR output. The concern is that this high-voltage
signal can overload the codec input and cause distor-
tion of the (desired) ac signal. Therefore, some sort of
PPM rejection scheme must be employed, see Figure
1. The L9217 outputs on the PPMOUT pin, which is the
output of the PPM input amplifier. Connecting a resis-
tor, R
PPM,
from PPMOUT to node TG will provide a path
for a hybrid reject of the returned meter pulse signal.
The return path from tip and ring to VITR for the PPM
signal is through the internal AX amplifier. TG is the
input to this amplifier. Through R
PPM
, by applying a
PPM signal equal in magnitude, but 180 degrees out of
phase to the returned PPM signal at TG, the PPM sig-
nal is cancelled, preventing overload at the codec
input. Even if the cancellation is not perfect, the idea is
to reduce the PPM signal so as not to overload the
codec. Codecs typically have a low-pass filter at their
input to reject any residual meter pulse signal.
The value of R
PPM
is selected by:
R
PPM
=
[{(V
PPMIN
x
10)/(R
PPMLOAD
+
R
DC
+
2R
P
)}/201.2]
–1
For undistorted transmission of meter pulse signals,
increase the overhead as described in the Overhead
Voltage section of this data sheet.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| L9218A | 制造商:AGERE 制造商全稱:AGERE 功能描述:Low-Cost Line Interface |
| L9219A | 制造商:AGERE 制造商全稱:AGERE 功能描述:Low-Cost Line Interface with Reverse Battery and Dual Current Limit |
| L9222 | 功能描述:功率驅動器IC Quad Inv Tran Switch RoHS:否 制造商:Micrel 產品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| L9222_04 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:QUAD INVERTING TRANSISTOR SWITCH |
| L9222D | 功能描述:功率驅動器IC Quad Inv Tran Switch RoHS:否 制造商:Micrel 產品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時間: 下降時間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
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