- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358880 > LMH6639 (National Semiconductor Corporation) 190MHz Rail-to-Rail Output Amplifier with Disable PDF資料下載
參數(shù)資料
| 型號： | LMH6639 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 190MHz Rail-to-Rail Output Amplifier with Disable |
| 中文描述： | 190MHz軌到軌輸出放大器，具有禁用 |
| 文件頁數(shù)： | 14/17頁 |
| 文件大?。?/td> | 649K |
| 代理商： | LMH6639 |
Application Notes
MULTIPLEXING 5 AND 10MHz
The LMH6639 may be used to implement a circuit which
multiplexes two signals of different frequencies. Three
LMH6639 high speed op-amps are used in the circuit of
Figure 2
to accomplish the multiplexing function. Two
LMH6639 are used to provide gain for the input signals, and
the third device is used to provide output gain for the se-
lected signal.
Multiplexing signals “FREQ 1” and “FREQ 2” exhibit closed
loop non-inverting gain of +2 each based upon identical
330
resistors in the gain setting positions of IC1 and IC2.
The two multiplexing signals are combined at the input of
IC3, which is the third LMH6639. This amplifier may be used
as a unity gain buffer or may be used to set a particular gain
for the circuit.
1k resistors are used to set an inverting gain of 1 for IC3 in
the circuit of
Figure 2
.
Figure 3
illustrates the waveforms
produced. The upper trace shows the switching waveform
used to switch between the 5MHz and 10MHz multiplex
signals. The lower trace shows the output waveform consist-
ing of 5MHz and 10MHz signals corresponding to the high or
low state of the switching signal.
In the circuit of
Figure 2
, the outputs of IC1 and IC2 are tied
together such that their output impedances are placed in
parallel at the input of IC3. The output impedance of the
disabled amplifier is high compared both to the output im-
pedance of the active amplifier and the 330
gain setting
resistors. The closed loop output resistance for the
LMH6639 is around 0.2
. Thus the active state amplifier
output impedance dominates the input node to IC3, while the
disabled amplifier is assured of a high level of suppression of
unwanted signals which might be present at the output.
SHUTDOWN OPERATION
With SD pin left floating, the device enters normal operation.
However, since the SD pin has high input impedance, it is
best tied to V
+
for normal operation. This will avoid inadvert-
ent shutdown due to capacitive pick-up from nearby nodes.
LMH6639 will typically go into shutdown when SD pin is
more than 1.7V below V
+
, regardless of operating supplies.
The SD pin can be driven by push-pull or open collector
(open drain) output logic. Because the LMH6639’s shutdown
is referenced to V+, interfacing to the shutdown logic is
rather simple, for both single and dual supply operation, with
either form of logic used. Typical configurations are shown in
Figure 4
and
Figure 5
below for push-pull output:
Common voltages for logic gates are +5V or +3V. To ensure
proper power on/off with these supplies, the logic should be
able to swing to 3.4V and 1.4V minimum, respectively.
20030247
Note: Pin numbers pertain to SOIC-8 package
FIGURE 2. Multiplexer
20030248
FIGURE 3. Switching between 5 and 10MHz
20030271
FIGURE 4. Shutdown Interface (Single Supply)
20030272
FIGURE 5. Shutdown Interface (Dual Supplies)
L
www.national.com
14
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LMH6639MA | 190MHz Rail-to-Rail Output Amplifier with Disable |
| LMH6639MAX | 190MHz Rail-to-Rail Output Amplifier with Disable |
| LMH6639MF | 190MHz Rail-to-Rail Output Amplifier with Disable |
| LMH6639MFX | 190MHz Rail-to-Rail Output Amplifier with Disable |
| LMH6640 | TFT-LCD Single, 16V Rail-to-Rail High Output Operational Amplifier |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LMH6639MA | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6639MA/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6639MAX | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6639MAX/NOPB | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| LMH6639MF | 功能描述:運算放大器 - 運放 RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。