SN74LS14 Schmitt触发

引脚配置

Pin Number	Pin Name	Description
1,3,5,11,13,15	施密特输入引脚	Input pins of the Schmitt trigger
2,4,6,10,12,14	Schmitt Output Pins	Output pins of the Schmitt trigger
7	地面	Connected to the ground of the system
14	Vcc (+5V)	Resets all outputs as low. Must be held high for normal operation

Features

• Schmitt Trigger – Hex Inverter
• Operating Voltage: 5V
• Low Level Hysteresis voltage: 0.25V
• High Level Hysteresis voltage: 3.4V
• Output current High: -0.4mA
• Output current Low: 8.0mA
• 通常滞后电压:0.8 v
• Typical Rise Time: 12nS
• Typical Fall Time: 12nS
• Available in 14-pin PDIP, GDIP, PDSO packages

Note:完整的技术细节可以在SN74LS14数据表given at the end of this page.

SN74LS14 Equivalents

74HC14

Alternatives Schmitt Triggers

CD40106，TC4584，MC14584

在哪里使用SN74LS14 IC

TheSN74LS14is a hex逆变器施密特触发器，这意味着它在其中有6个倒置的施密特触发。Schmitt触发器用于避免滞后问题。我也可以用来将嘈杂的单曲平滑为锋利的单曲。施密特触发门我们可以将正弦波或三角波转换为方波。如果需要，它也可以用作逻辑逆变器。Schmitt触发器也可用于拒绝按钮或其他嘈杂的输入设备。

So if you are looking for an IC which can help you to get of switching noise or to create sharp square wave signals based on an input signal then this IC could be the right choice or you.

How to Use 74LS14 IC

如前面提到的74LS14有六个反相施密特扳机门which can be used as six individual gates. The simplified internal structure can be given as below.

Each of these 6 gates can be used individually based on our application. Since the gates are inverting we can also combine two gates together to form a non-inverting gate. The input signal can be a noise square wave or any signal wave that oscillates between the low and high hysteresis voltage.

The unique and special functionality of a Schmitt trigger is to toggle the output based on the input signal without any noise. This is achieved by using a hysteresis band inside which no switching takes place. The voltage level in this band from VT+ to VT-. In our SN74LS14 IC the VT+ is 3.4V and VT- is 0.2V.

这意味着仅当输入电压（VIN）大于3.4V时，输出才能获得较低，并且仅当输入电压低于0.2V时才能获得高。在0.2V - 3.4V之间的输入电压中发生的任何噪声都不会影响输出电压。您可以使用Application report from TIto know more about using this IC

切换时间为74HC14 IC

The gates in74HC14take some time to provide output to the given input. This time delays are called switching times. Each gate will take time to turn ON and OFF. For understanding this better let us consider the switching diagram of a gate.

There are two delays which happen when switching. These two parameters are RISETIME (t_PHL）和秋季时间（t_PLH）。

In the graph, VoH goes LOW when INPUT reaches a threshold and VoH goes HIGH when INPUT goes lower than threshold voltage. In another sense it is the output voltage.

As you can see in the graph there is time delay between LOGIC INPUT going HIGH and VoH going LOW. This delay in providing response is called RISETIME (t_PHL）。The RISETIME (t_PHL) is 12ns.

Similarly in the graph there is time delay between LOGIC INPUT going LOW and VoH going HIGH at the OUTPUT. This delay in providing response is called FALLTIME (t_PLH）。秋季时间（t_PLH) is 12ns.

每个周期的总数为24N。这些延迟必须以较高的频率考虑，否则由于虚假触发，我们将遇到重大错误。

Applications

• Noise removing circuits
• 拒绝电路
• Hysteresis controller
• Dead band filter

2D模型