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參數資料
| 型號： | L9218A |
| 英文描述： | CAP CER 330PF 3.15KVDC R3 RAD |
| 中文描述： | 低成本線接口 |
| 文件頁數： | 19/30頁 |
| 文件大小： | 378K |
| 代理商： | L9218A |
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Agere Systems Inc.
19
Data Sheet
November 2001
L9218A/G Low-Cost Line Interface
Applications
(continued)
dc Applications
Battery Feed
The dc feed characteristic can be described by:
where:
I
L
= dc loop current.
V
T/R
= dc loop voltage.
|
V
BAT
|
= battery voltage magnitude.
V
OH
= overhead voltage. This is the difference between
the battery voltage and the open loop tip/ring
voltage.
R
L
= loop resistance, not including protection resistors.
R
P
= protection resistor value.
R
dc
= SLIC internal dc feed resistance.
The design begins by drawing the desired dc template.
An example is shown in Figure 13.
Notes:
V
BAT
= –48 V.
I
LIM
= 22 mA.
R
dc1
= 115
.
Figure 13. Loop Current vs. Loop Voltage
Starting from the on-hook condition and going through
to a short circuit, the curve passes through the follow-
ing two regions:
Region 1: On-hook and low-loop currents. The slope
corresponds to the dc resistance of the
SLIC, R
dc1
(70
typical). The open circuit
voltage is the battery voltage minus the over-
head voltage of the device, V
OH
(6.5 V typi-
cal). These values are suitable for most
applications but can be adjusted if needed.
Region 2: Current limit. The dc current is limited to a
starting value determined by external resis-
tor R
PROG
, an internal current source, and
the gain from tip/ring to pin DCOUT.
Current Limit
With the B0/B1 logic inputs set to 11 (low current limit),
current limit with a 100
load is given by the following
equation:
0.637 R
PROG
(k
) + 2 mA= I
LIM
x (mA)
The relationship between low current limit (B0 = 1,
B1 = 1) and high current limit (B0 = 1, B1 = 0) is
LIMIT
Low
(
)
I
LIMIT
High
(
)
= 0.7
Overhead Voltage
In order to drive an on-hook ac signal, the SLIC must
set up the tip and ring voltage to a value less than the
battery voltage. The amount that the open loop voltage
is decreased relative to the battery is referred to as the
overhead voltage, expressed as the following equation:
V
OH
= |V
BAT
| – (V
PT
– V
PR
)
Without this buffer voltage, amplifier saturation will
occur and the signal will be clipped. The L9218 is auto-
matically set at the factory to allow undistorted on-hook
transmission of a 3.14 dBm signal into a 900
loop
impedance.
I
L
R
L
+
R
dc
+
2R
P
---------------------------------
=
V
T/R
R
L
2R
P
---------------------------------------------
R
dc
L
+
+
=
0
10
20
50
0
20
30
40
50
LOOP VOLTAGE (V)
30
40
10
L
1
12.5 k
–1
R
dc1
I
LIM
TESTED
I
LIM
ONSET
12-3050 (F).i
I
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| L9222-D | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:QUAD INVERTING TRANSISTOR SWITCH |
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