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參數(shù)資料
| 型號(hào)： | LM6172AMWGRQML |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 音頻／視頻放大 |
| 英文描述： | VIDEO AMPLIFIER, CDSO16 |
| 封裝： | CERAMIC, SOIC-16 |
| 文件頁數(shù)： | 3/21頁 |
| 文件大?。?/td> | 635K |
| 代理商： | LM6172AMWGRQML |
1
2 LM6172 Simplified Schematic
Application Notes
LM6172 Performance Discussion
The LM6172 is a dual high-speed, low power, voltage feed-
back amplifier. It is unity-gain stable and offers outstanding
performance with only 2.3 mA of supply current per channel.
The
combination
of
100
MHz
unity-gain
bandwidth,
3000V/s slew rate, 50 mA per channel output current and
other attractive features makes it easy to implement the
LM6172 in various applications. Quiescent power of the
LM6172 is 138 mW operating at ±15V supply and 46 mW at
±5V supply.
LM6172 Circuit Operation
The class AB input stage in LM6172 is fully symmetrical and
has a similar slewing characteristic to the current feedback
amplifiers. In the LM6172 Simplified Schematic, Q1 through
Q4 form the equivalent of the current feedback input buffer,
R
E the equivalent of the feedback resistor, and stage A buff-
ers the inverting input. The triple-buffered output stage iso-
lates the gain stage from the load to provide low output im-
pedance.
LM6172 Slew Rate Characteristic
The slew rate of LM6172 is determined by the current avail-
able to charge and discharge an internal high impedance
node capacitor. This current is the differential input voltage
divided by the total degeneration resistor R
E. Therefore, the
slew rate is proportional to the input voltage level, and the
higher slew rates are achievable in the lower gain configura-
tions.
When a very fast large signal pulse is applied to the input of
an amplifier, some overshoot or undershoot occurs. By plac-
ing an external series resistor such as 1 k
to the input of
LM6172, the slew rate is reduced to help lower the over-
shoot, which reduces settling time.
Reducing Settling Time
The LM6172 has a very fast slew rate that causes overshoot
and undershoot. To reduce settling time on LM6172,a1k
resistor can be placed in series with the input signal to de-
crease slew rate. A feedback capacitor can also be used to
reduce overshoot and undershoot. This feedback capacitor
serves as a zero to increase the stability of the amplifier cir-
cuit. A 2 pF feedback capacitor is recommended for initial
evaluation. When the LM6172 is configured as a buffer, a
feedback resistor of 1 k
must be added in parallel to the
feedback capacitor.
Another possible source of overshoot and undershoot
comes from capacitive load at the output. Please see the
section “Driving Capacitive Loads” for more detail.
Driving Capacitive Loads
Amplifiers driving capacitive loads can oscillate or have ring-
ing at the output. To eliminate oscillation or reduce ringing,
an isolation resistor can be placed as shown in
Figure 1. The
combination of the isolation resistor and the load capacitor
forms a pole to increase stability by adding more phase mar-
gin to the overall system. The desired performance depends
on the value of the isolation resistor; the bigger the isolation
resistor, the more damped (slow) the pulse response be-
comes. For LM6172, a 50
isolation resistor is recom-
mended for initial evaluation.
DS012581-55
www.national.com
11
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM6172IM | 功能描述:運(yùn)算放大器 - 運(yùn)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 |
| LM6172IM/NOPB | 功能描述:運(yùn)算放大器 - 運(yùn)放 Dual High Speed,Low Pwr Amp 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 |
| LM6172IM/NOPB | 制造商:Texas Instruments 功能描述:Operational Amplifier (Op-Amp) IC |
| LM6172IMX | 功能描述:運(yùn)算放大器 - 運(yùn)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 |
| LM6172IMX/NOPB | 功能描述:運(yùn)算放大器 - 運(yùn)放 DUAL HI-SPD LO-PWR LO-DIST VOL FDBK AMP 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 |
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