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Difference between active crystal oscillator and passive crystal oscillator

2020-12-06 11:04:31 Procedural ape without hair loss

Catalog

1、 Passive crystal oscillator

2、  Active crystal oscillator

3、 The difference between active crystal oscillator and passive crystal oscillator  


Crystal oscillator can be divided into quartz crystal oscillator and ceramic crystal oscillator from the material , But from the attribute crystal oscillator can be divided into passive crystal oscillator :crystal( Crystal ) And active crystal oscillator :oscillator( oscillator ). Quartz crystal oscillator and ceramic crystal oscillator from the appearance is very helpful to distinguish , After all, there are two totally different materials . But the passive crystal oscillator and the active crystal oscillator sometimes make people silly and unclear .

1、 Passive crystal oscillator

Passive crystal oscillator has 2 A nonpolar component with five pins , The oscillation signal can be produced by means of clock circuit , It can't oscillate itself .

Passive crystal oscillator

The signal quality of passive crystal oscillator is poor , It is usually necessary to match the peripheral circuits precisely ( Capacitors for signal matching 、 inductance 、 Resistance, etc ), When changing crystals with different frequencies, the peripheral configuration circuit also needs to be adjusted accordingly .

Passive crystal oscillator application circuit

It is generally recommended to use quartz crystal with high precision , Try not to use ceramic crystals with low precision . 

2、  Active crystal oscillator

Active crystal oscillator has 4 One pin , It's a complete oscillator , Besides quartz crystal , And transistors and resistive and capacitive components , So it's bigger , Just need power , Can output better waveform .

The active crystal oscillator is packaged with 4 One pin , Respectively VCC( voltage )、GND( The earth )、OUT( Clock signal output )、NC( Empty feet ).

Active crystal front
Active crystal oscillator back

Active crystal oscillator does not need CPU The internal oscillator of , The signal is stable , Good quality , And the connection is simple ( Mainly do a good job in power filter , A filter and a network usually use a capacitor , Output with a small resistance filter signal can be ), There is no need for complex configuration circuits .

Active crystal oscillator application circuit

3、 The difference between active crystal oscillator and passive crystal oscillator  

1、 Active crystal oscillator is more expensive , But the active crystal oscillator itself can vibrate . And whether it's a passive crystal oscillator , Or active crystal oscillator , Both have their own advantages and disadvantages , If you consider the cost of the product , It is suggested that passive crystal oscillator circuit can be selected ; If you consider the performance of the product , It is suggested to choose active crystal oscillator circuit , Time saving and convenience can also guarantee the product performance .

2、 The highest accuracy of passive crystal oscillator is 5ppm, The accuracy of active crystal oscillator can reach 0.1ppm. The higher the accuracy , Frequency stability is also better . The stability of active crystal oscillator is better than that of passive crystal oscillator , But it also has its own small defects , The signal level of active crystal oscillator is fixed , So we need to choose the right output level , Poor flexibility .

3、 Active crystal oscillator 4 A foot , A power supply , One ground , A signal output , One NC( Empty feet ). There is a dot marked with 1 foot , Counter clockwise ( Pin down ) Respectively 2、3、4.

4、 Passive crystal oscillator has 2 One pin , Need to rely on the external clock circuit ( To the Lord IC Internal oscillation circuit ) To generate an oscillation signal , It can't oscillate itself .


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