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參數(shù)資料
| 型號(hào)： | LMV7219M7X |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | 7 nsec, 2.7V to 5V Comparator with Rail-to Rail Output |
| 中文描述： | COMPARATOR, 8000 uV OFFSET-MAX, 12 ns RESPONSE TIME, PDSO5 |
| 封裝： | SC-70, 5 PIN |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 282K |
| 代理商： | LMV7219M7X |
Application Section
(Continued)
This method is recommended for additional hysteresis of up
to a few hundred millivolts. Beyond that, the impedance of
R3 is low enough to affect the bias string and adjustment of
R1 may be also required.
Circuit Layout and Bypassing
The LMV7219 requires high-speed layout. Follow these lay-
out guidelines:
1. Power supply bypassing is critical, and will improve stabil-
ity and transient response. A decoupling capacitor such as
0.1μF ceramic should be placed as close as possible to V
+
pin. An additional 2.2μF tantalum capacitor may be required
for extra noise reduction.
2. Keep all leads short to reduce stray capacitance and lead
inductance. It will also minimize unwanted parasitic feedback
around the comparator.
3. The device should be soldered directly to the PC board in-
stead of using a socket.
4. Use a PC board with a good, unbroken low inductance
ground plane. Make sure ground paths are low-impedance,
especially were heavier currents are flowing.
5. Input traces should be kept away from output traces. This
can be achieved by running a topside ground plane between
the output and inputs.
6. Run the ground trace under the device up to the bypass
capacitor to shield the inputs from the outputs.
7. To prevent parasitic feedback when input signals are
slow-moving, a small capacitor of 1000pF or less can be
placed between the inputs. It can also help eliminate oscilla-
tions in the transition region. However, this capacitor can
cause some degradation to tpd when the source impedance
is low.
Zero-Crossing Detector
The inverting input is connected to ground and the non-
inverting input is connected to 100mVp-p signal. As the sig-
nal at the non-inverting input crosses 0V, the comparator’s
output Changes State.
Threshold Detector
Instead of tying the inverting input to 0V, the inverting input
can be tied to a reference voltage. The non-inverting input is
connected to the input. As the input passes the V
REF
thresh-
old, the comparator’s output changes state.
Crystal Oscillator
A simple crystal oscillator using the LMV7219 is shown be-
low. Resistors R1 and R2 set the bias point at the compara-
tor’s non-inverting input. Resistors R3, R4 and C1 sets the
inverting input node at an appropriate DC average level
based on the output. The crystal’s path provides resonant
positive feedback and stable oscillation occurs. The output
duty cycle for this circuit is roughly 50%, but it is affected by
resistor tolerances and to a lesser extent by the comparator
offset.
DS101054-21
FIGURE 2. Additional Hysteresis
DS101054-22
FIGURE 3. Zero-Crossing Detector
DS101054-23
FIGURE 4. Threshold Detector
DS101054-24
FIGURE 5. Crystal Oscillator
L
www.national.com
9
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| LMV7219M7X/NOPB | 功能描述:校驗(yàn)器 IC RoHS:否 制造商:STMicroelectronics 產(chǎn)品: 比較器類型: 通道數(shù)量: 輸出類型:Push-Pull 電源電壓-最大:5.5 V 電源電壓-最小:1.1 V 補(bǔ)償電壓（最大值）:6 mV 電源電流（最大值）:1350 nA 響應(yīng)時(shí)間: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SC-70-5 封裝:Reel |
| LMV721IDBVR | 功能描述:運(yùn)算放大器 - 運(yùn)放 10-MHz L-N L-V L-P 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 |
| LMV721IDBVRG4 | 功能描述:運(yùn)算放大器 - 運(yùn)放 10-MHz L-N L-V L-P 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 |
| LMV721IDCKR | 功能描述:運(yùn)算放大器 - 運(yùn)放 10-MHz L-N L-V L-P 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 |
| LMV721IDCKRG4 | 功能描述:運(yùn)算放大器 - 運(yùn)放 10-MHz L-N L-V L-P 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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