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| 型号： | LT1794ISW |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 运动控制电子 |
| 英文描述： | Dual 500mA, 200MHz xDSL Line Driver Amplifier |
| 中文描述： | DUAL OP-AMP, 7500 uV OFFSET-MAX, 200 MHz BAND WIDTH, PDSO20 |
| 封装： | 0.300 INCH, PLASTIC, SO-20 |
| 文件页数： | 11/20页 |
| 文件大小： | 275K |
| 代理商： | LT1794ISW |
11
LT1794
Figure 7. I
Q
vs I
LOAD
APPLICATIOU
With no signal being placed on the line and the amplifier
biased for 10mA per amplifier supply current, the quies-
cent driver power dissipation is:
P
DQ
= 24V 20mA = 480mW
This can be reduced in many applications by operating
with a lower quiescent current value.
When driving a load, a large percentage of the amplifier
quiescent current is diverted to the output stage and
becomes part of the load current. Figure 7 illustrates the
total amount of biasing current flowing between the + and
– power supplies through the amplifiers as a function of
load current. As much as 60% of the quiescent no load
operating current is diverted to the load.
At full power to the line the driver power dissipation is:
P
D(FULL)
= 24V 8mA + (12V – 2V
RMS
) 57mA
RMS
+ [|–12V – (–2V
RMS
)|] 57mA
RMS
P
D(FULL)
= 192mW + 570mW + 570mW = 1.332W
The junction temperature of the driver must be kept less
than the thermal shutdown temperature when processing
a signal. The junction temperature is determined from the
following expression:
T
J
= T
AMBIENT
(
°
C) + P
D(FULL)
(W)
θ
JA
(
°
C/W)
θ
JA
is the thermal resistance from the junction of the
LT1794 to the ambient air, which can be minimized by
W
U
U
I
LOAD
(mA)
–240
–200
–160
–120
–80
–40
0
40
80
120
160
200
240
T
Q
10
15
20
1794 F07
5
0
25
heat-spreading PCB metal and airflow through the enclo-
sure as required. For the example given, assuming a
maximum ambient temperature of 85
°
C and keeping the
junction temperature of the LT1794 to 140
°
C maximum,
the maximum thermal resistance from junction to ambient
required is:
θ
JA MAX
(
C
C
W
C W
/
°
)
–
.
.
=
°
°
=
140
85
1 332
41 3
Heat Sinking Using PCB Metal
Designing a thermal management system is often a trial
and error process as it is never certain how effective it is
until it is manufactured and evaluated. As a general rule,
the more copper area of a PCB used for spreading heat
away from the driver package, the more the operating
junction temperature of the driver will be reduced. The
limit to this approach however is the need for very com-
pact circuit layout to allow more ports to be implemented
on any given size PCB.
Fortunately xDSL circuit boards use multiple layers of
metal for interconnection of components. Areas of metal
beneath the LT1794 connected together through several
small 13 mil vias can be effective in conducting heat away
from the driver package. The use of inner layer metal can
free up top and bottom layer PCB area for external compo-
nent placement.
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| LT1794ISW#PBF | 功能描述:IC OPAMP 200MHZ DUAL 20-SOIC RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:1 系列:- 类型:线路收发器 驱动器/接收器数:5/3 规程:RS232 电源电压:3 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:Digi-Reel® 产品目录页面:918 (CN2011-ZH PDF) 其它名称:296-25096-6 |
| LT1794ISW#TR | 功能描述:IC OPAMP 200MHZ DUAL 20-SOIC RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LT1794ISW#TRPBF | 功能描述:IC OPAMP 200MHZ DUAL 20-SOIC RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LT1795 | 制造商:LINER 制造商全称: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 类别:集成电路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 标准包装:150 系列:- 放大器类型:音频 电路数:2 输出类型:- 转换速率:5 V/µs 增益带宽积:12MHz -3db带宽:- 电流 - 输入偏压:100nA 电压 - 输入偏移:500µV 电流 - 电源:6mA 电流 - 输出 / 通道:50mA 电压 - 电源，单路/双路(±):4 V ~ 32 V，±2 V ~ 16 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:8-TSSOP 包装:管件 |
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