How can an active crystal oscillator replaces a passive oscillator?
Ⅰ. passive oscillator application principle: It needs to form a resonant circuit with capacitors,
resistors and inductors, etc., sine wave output (waveform amplitude is small),
after the clock chip shaping, the final output as a square wave.
Older solutions: It direct uses of sine wave, such as radar, radio transmitting station, etc.
Ⅱ. Active crystal oscillator application principle: It has a built-in best matching oscillator including IC shaping circuit,
a complete oscillator with a square waveform output and a direct interface to digital signal circuits.
1. Advantages: High amplitude waveform with upper and lower edge time, suitable for digital circuits.
2. Applications: Most current mainstream digital products.
Ⅲ. Active crystal oscillator replacement for passive oscillator:
1、Provide power supply (rated voltage input)
2、active crystal oscillator signal output pin can connect to
the original passive oscillator corresponding to the IC input pin or output pin,
but based on the IC is different, sometimes need to try.
Additional notes.
As the active crystal oscillator output is a square wave, after entering the original passive crystal IC circuit,
it will be shaped again. IC for sine wave can be done to rectify into a square wave,
so the other wave again rectified into a square wave, there will be no problem.
In addition, when an active crystal oscillator replaces an existing passive oscillator, we usually use a bypass,
i.e. bypassing the original passive crystal circuit. In other words,
the capacitive and resistive components of the resonant circuit associated with the passive oscillator are removed.