- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄10559 > LT1794ISW#PBF (Linear Technology)IC OPAMP 200MHZ DUAL 20-SOIC PDF資料下載
參數(shù)資料
| 型號(hào)： | LT1794ISW#PBF |
| 廠商： | Linear Technology |
| 文件頁(yè)數(shù)： | 7/20頁(yè) |
| 文件大?。?/td> | 0K |
| 描述： | IC OPAMP 200MHZ DUAL 20-SOIC |
| 標(biāo)準(zhǔn)包裝： | 38 |
| 類型： | 線路驅(qū)動(dòng)器，發(fā)射器 |
| 驅(qū)動(dòng)器/接收器數(shù)： | 2/0 |
| 規(guī)程： | xDSL |
| 電源電壓： | 18V |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 20-SOIC（0.295"，7.50mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 20-SOIC |
| 包裝： | 管件 |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)當(dāng)前第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)第16頁(yè)第17頁(yè)第18頁(yè)第19頁(yè)第20頁(yè)
15
LT1794
Note that the overall gain is increased:
V
RR
R
nR R
R
O
I
PP
P
FG
P
=
+
()
+
() +
()
[]+
()
[]
22
1
12
1
11
1
/
//
/
A simpler method of using positive feedback to reduce the
back-termination is shown in Figure 15. In this case, the
drivers are driven differentially and provide complemen-
tary outputs. Grounding the inputs, we see there is invert-
ing gain of –RF/RP from –VO to VA
VA = VO (RF/RP)
and assuming RP >> RL, we require
VA = VO (1 – 1/n)
solving
RF/RP = 1 – 1/n
So to reduce the back-termination by a factor of 3 choose
RF/RP = 2/3. Note that the overall gain is increased to:
VO/VI = (1 + RF/RG + RF/RP)/[2(1 – RF/RP)]
Using positive feedback is often referred to as active
termination.
Figure 17 shows a full-rate ADSL line driver incorporating
positive feedback to reduce the power lost in the back
termination resistors by 40% yet still maintains the proper
impedance match to the100
characteristic line imped-
ance. This circuit also reduces the transformer turns ratio
over the standard line driving approach resulting in lower
peak current requirements. With lower current and less
power loss in the back termination resistors, this driver
dissipates only 1W of power, a 30% reduction.
While the power savings of positive feedback are attractive
there is one important system consideration to be ad-
dressed, received signal sensitivity. The signal received
from the line is sensed across the back termination resis-
tors. With positive feedback, signals are present on both
ends of the RBT resistors, reducing the sensed amplitude.
Extra gain may be required in the receive channel to
compensate, or a completely separate receive path may be
implemented through a separate line coupling transformer.
A demo board, DC306A, is available for the LT1794. This
demo board is a complete line driver with an LT1361
receiver included. It allows the evaluation of both standard
and active termination approaches. It also has circuitry
built in to evaluate the effects of operating with reduced
supply current.
Considerations for Fault Protection
The basic line driver design, shown on the front page of
this data sheet, presents a direct DC path between the
outputs of the two amplifiers. An imbalance in the DC
biasing potentials at the noninverting inputs through
either a fault condition or during turn-on of the system can
create a DC voltage differential between the two amplifier
outputs. This condition can force a considerable amount
of current to flow as it is limited only by the small valued
back-termination resistors and the DC resistance of the
transformer primary. This high current can possibly cause
the power supply voltage source to drop significantly
impacting overall system performance. If left unchecked,
the high DC current can heat the LT1794 to thermal
shutdown.
APPLICATIO S I FOR ATIO
WU
UU
–
+
RBT
RF
RG
RP
RG
RL
–VI
VA
–VA
VI
–VO
VO
–
+
RBT
1794 F15
RF
RL
n
=
VO
VI
n =
1 –
2
FOR RBT =
RF
RP
RF
RP
+
RF
RG
1 +
1 –
RF
RP
1
()
Figure 15. Back Termination Using Differential Postive Feedback
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| VE-25T-IW-F4 | CONVERTER MOD DC/DC 6.5V 100W |
| MAX1284BESA+ | IC ADC 12BIT 400KSPS 8-SOIC |
| VI-JV0-MY-F4 | CONVERTER MOD DC/DC 5V 50W |
| VI-JV0-MY-F3 | CONVERTER MOD DC/DC 5V 50W |
| MAX1285BESA+ | IC ADC 12BIT 300KSPS 8-SOIC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LT1795 | 制造商:LINER 制造商全稱:Linear Technology 功能描述:Dual 500mA/50MHz Current Feedback Line Driver Amplifier |
| LT1795CFE | 功能描述:IC AMP CURR FEEDBCK DUAL 20TSSOP RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:150 系列:- 放大器類型:音頻 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:5 V/µs 增益帶寬積:12MHz -3db帶寬:- 電流 - 輸入偏壓:100nA 電壓 - 輸入偏移:500µV 電流 - 電源:6mA 電流 - 輸出 / 通道:50mA 電壓 - 電源，單路/雙路(±):4 V ~ 32 V，±2 V ~ 16 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:管件 |
| LT1795CFE#PBF | 功能描述:IC AMP CURR FEEDBCK DUAL 20TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:150 系列:- 放大器類型:音頻 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:5 V/µs 增益帶寬積:12MHz -3db帶寬:- 電流 - 輸入偏壓:100nA 電壓 - 輸入偏移:500µV 電流 - 電源:6mA 電流 - 輸出 / 通道:50mA 電壓 - 電源，單路/雙路(±):4 V ~ 32 V，±2 V ~ 16 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:管件 |
| LT1795CFE#TR | 功能描述:IC AMP LINE DRIVER DUAL 20-TSSOP RoHS:否 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:150 系列:- 放大器類型:音頻 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:5 V/µs 增益帶寬積:12MHz -3db帶寬:- 電流 - 輸入偏壓:100nA 電壓 - 輸入偏移:500µV 電流 - 電源:6mA 電流 - 輸出 / 通道:50mA 電壓 - 電源，單路/雙路(±):4 V ~ 32 V，±2 V ~ 16 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:管件 |
| LT1795CFE#TRPBF | 功能描述:IC AMP CURR FEEDBCK DUAL 20TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:150 系列:- 放大器類型:音頻 電路數(shù):2 輸出類型:- 轉(zhuǎn)換速率:5 V/µs 增益帶寬積:12MHz -3db帶寬:- 電流 - 輸入偏壓:100nA 電壓 - 輸入偏移:500µV 電流 - 電源:6mA 電流 - 輸出 / 通道:50mA 電壓 - 電源，單路/雙路(±):4 V ~ 32 V，±2 V ~ 16 V 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:8-TSSOP 包裝:管件 |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。