The post discuses the main specifications, datasheet and working principle of the IC LM567, which is a precise phase-locked loop with synchronous AM lock detection and power output device.
In simpler terms the IC LM567 IC is a tone decoder chip which is designed basically for recognizing a specified frequency band, and activating the output in response to the detection.
不用说，此芯片可用于许多不同的应用程序，最常见的是遥控器和安全系统领域。
框图
绝对最大等级
绝对最大额定值是指表示IC在电压，电流和功率耗散方面的最大耐受能力的值。下表解释了相关参数的IC LM567的绝对最大额定值：
Pinout Working and Specifications
参考上述IC LM 567内部配置图，可以从以下几点理解IC的引脚函数：
引脚＃4和引脚＃7分别为iC的正（VDD）和负（VSS）供应输入。
引脚＃3是输入的传感输入，用于检测给定的相锁环频率，换句话说，此引脚将用匹配中心频率锁定，该中心频率可以通过一对外部设置在IC内部RC网络。
引脚＃5和6用于通过设置R1，C1的值来创建中心频率，并且Sensing Input Pin＃3使用此频率来锁定并在PIN＃8处创建逻辑零这是IC的输出引脚。
Output Pin#8 is normally logic high and becomes logic zero as soon as a matching frequency is detected at pin#3 of the IC.
引脚＃1和引脚＃2用于确保对所涉及频率的正确过滤，因此由于任何现有的伪造或流浪噪声干扰，IC不会产生任何错误输出。
LM567的主要特征：
Extensive settable frequency range (0.01 Hz to 500 kHz), meaning the sensing passband may be set right from 0.1 to 500 kHz, giving an option of a huge range so that unlimited unique configuration can be achieved from this chip.
高度稳定的中心频率，可以确保精确的通带限制，从而使单元通过检测功能非常可靠。
Independently controllable bandwidth (up to 14%), as the feature suggests, the bandwidth is also adjustable to a reasonable degree.
High out-band signal, and noise rejection, which again assures high reliability during the detection and implementation of the said functions.
Logic-compatible output with 100 mA current sinking capability, which allows the output to handle relatively higher loads without employing an additional buffer stage such as a transistor driver stage.
对错误信号的固有免疫力，这确保芯片由于频率检测不正确或存在流浪或虚假瞬时信号而不会产生错误的结果。
具有外部电阻器的20比1范围内的频率调节，此功能再次使芯片高度柔韧性和动态性。
与IC LM567相关的三个重要参数可以通过以下几点理解：
相锁定环中心频率
It’s the free running frequency of the in-built current controlled oscillator circuitry in the
没有输入信号。
Detection Bandwidth
This is the frequency range which may be provided to the above center frequency, within which the presence of an input signal having a threshold voltage of above 20mV causes the output of the IC to become low. This feature refers to the loop capture range.
锁定范围
它是最大频率范围，可以使输出在存在高于20mV的相关输入信号的情况下切换为逻辑零。
Detection Band
It is the magnitude which indicates the level of optimal detection, focused around the center frequency. It’s given by the formula:
检测频段=（fmax + fmin - 2fo）/2fo，
where fmax and fmin are the frequencies thresholds of the detection band, fo is the center frequency
申请提示
The IC567 may be considered as a versatile chip because it provides an unlimited range of applications in the field of electronics, some of them are discussed below:
- 接触音调解码：使用此芯片使用时，人触摸响应可能会产生不同的频率，可以通过使用许多IC LM567配置来适当解码。
- Carrier current remote controls: Our existing mains wiring can be very effectively used as a medium of transfer for communicating between the rooms or for controlling appliances remotely from one room to the other. The actions can be implemented by using a LM567 IC.
- 红外控件（远程电视等）：由于LM567的中心频率紧密锁定，因此可以精确地从给定的手机检测IR波。与普通的IR遥控器不同，该电路更适合流浪RF或通过切换AC电源器具产生的IR扰动。
- 频率监视和控制：再次，由于LM567 IC具有内置的精确频率检测范围，可用于准确监视给定的频率范围。
- Wireless intercom: Just like Carrier current remote controls, the IC LM567 may also be suitably implemented in wireless intercom systems.
- Precision oscillator: The phase locked loop feature in the proposed IC also facilitates its application as a precision oscillator for achieving precisely adjusted oscillations or frequencies.
