The difference between active crystal oscillator and passive crystal oscillator

There are many crystal oscillator manufacturers on the market, and the more well-known ones are Renesas Electronics, STMic, Japan Crystal, NDK crystal oscillator, TXC crystal oscillator, etc. Domestic crystal oscillator brands such as Taijing, Whalen, TROQ (Chuangjie) and so on. TROQ is a domestic brand independently founded by Jinhua Chuangjie Electronics, which was founded by Hu Xiangshu and Wu Qunxian, who have more than 50 years of scientific research experience.

Since its establishment, it has more than 20 years of experience in Taiwanese and Japanese first-line crystal oscillator brand foundry, and has also passed AEC-Q vehicle specification certification, reliable quality, 18,000 standard dust-free workshop, and monthly production capacity of 100 million. Welcome to inquire to receive free samples, and at the same time provide you with free fae technical support.

1. Passive crystal oscillator - passive crystal oscillator needs to use an oscillator in the DSP chip, and there is a suggested connection method on the datasheet. There is no voltage problem with passive crystals, the signal level is variable, that is to say, it is determined according to the starting circuit, the same crystal can be applied to a variety of voltages, can be used for a variety of DSP with different clock signal voltage requirements, and ** is usually low, so for general applications if conditions permit, it is recommended to use crystals, which is especially suitable for producers with rich product lines and large quantities. Compared with crystal oscillators, passive crystals have the disadvantage of poor signal quality, and usually need to accurately match peripheral circuits (inductance, filter signals for signal matching), and do not require complex configuration circuits.

The usual usage of active crystal oscillator: one pin is suspended, two pins are grounded, three pins are connected to output, and four pins are connected to voltage. Compared with passive crystals, the defect of active crystal oscillator is that its signal level is fixed, and it is necessary to choose the appropriate output level, which is less flexible and high.

3. Active crystal oscillators are usually larger than passive crystals, but now many active crystal oscillators are surface-mounted, and the volume is comparable to the crystal, and some are even smaller than many crystals.

1. Different pins.

1. Passive crystal oscillator: It is a non-polar element with two pins. It requires a clock circuit to generate an oscillating signal, and it does not oscillate automatically.

2. Active crystal oscillator: There are four pins, which is a complete oscillator. In addition to quartz crystals, there are transistors and resistive and capacitive components, depending on the circuit you are using. If there is a clock circuit, a passive circuit is used, otherwise an active circuit is used.

Second, the need for oscillators is different.

1. Passive crystal oscillator: the oscillator in the DSP chip is required, the passive crystal has no voltage problem, the signal level is variable, that is to say, it is determined according to the oscillator circuit, the same crystal can be applied to various voltages, can be used for a variety of different clock signal voltage requirements of the DSP, usually ** low.

2. Active crystal oscillator: the internal oscillator of the DSP is not required, the signal is ***, and it is relatively stable, and the connection is relatively simple to do a good job of power filter, usually using capacitor inductance PI filter network, and the filter signal with small resistance value can be output, without complex configuration.

Active crystal oscillators require a power supply, but no additional capacitors. It contains an oscillator inside. Usually it can be connected to one pin of the CPU.

Passive crystals do not require a power supply, but they often need to be used in conjunction with capacitors, which are usually connected to two pins of the CPU.

Crystal oscillators can be divided into two categories: quartz crystal oscillators and ceramic crystal oscillators from the material, and the subordinate crystal oscillators can be divided into passive crystal oscillators and active oscillators.

Quartz crystal oscillator and ceramic crystal oscillator are very conducive to distinguishing from each other in appearance, after all, they are also two completely different materials.

The passive crystal oscillator is a non-polar component with two pins, which needs to be used by the clock circuit to generate an oscillation signal, and cannot oscillate by itself. The signal quality of passive crystal oscillator is poor, and it is usually necessary to accurately match the peripheral circuits (capacitors, inductors, resistors, etc. for signal matching), and the peripheral configuration circuits need to be adjusted accordingly when replacing crystals of different frequencies.

The active crystal oscillator has 4 pins and is a complete oscillator, in which in addition to the quartz crystal, there are transistors and resistor-capacitance components, so it is large in size, and only needs a power supply to output a better waveform.

First, the pins are different:

1.A passive crystal oscillator is a non-polar component with two pins, which needs to be used by a clock circuit to generate an oscillation signal, and cannot oscillate on its own.

2.The active crystal oscillator has 4 pins, which is a complete oscillator, in addition to the quartz crystal, there are transistors and resistor-capacitance components mainly depending on the circuit you are applying to, if there is a clock circuit, use passive, otherwise use active.

Second, the need for oscillators is different.

1. The passive crystal needs to use the oscillator in the DSP chip, the passive crystal has no voltage problem, the signal level is variable, that is to say, it is determined according to the starting circuit, the same crystal can be applied to a variety of voltages, can be used for a variety of DSP with different clock signal voltage requirements, and ** is usually low.

2. The active crystal oscillator does not need the internal oscillator of DSP, the signal is relatively stable, and the connection method is relatively simple (mainly to do a good job in power filtering, usually using a PI filter network composed of capacitors and inductors, and the output terminal can filter the signal with a small resistance resistance), and does not require complex configuration.

Work is carried out by the piezoelectric effect of quartz.

The working principle is: electrodes are plated on both sides of the quartz crystal sheet, and a certain voltage is added to the two electrodes, because quartz has a piezoelectric effect, the voltage is formed, and the deformation will naturally occur, so as to provide a sinusoidal waveform to the IC. After passing through the IC's internal shaping and PLL circuits, a square wave is generated and then fed to the subordinate circuit.

A passive crystal oscillator is a crystal that must be combined with peripheral circuits to form an oscillator to output a signal of a specific frequency, and this oscillator needs to provide power. For example, MCU can use passive crystal oscillator because it has a circuit that constitutes an oscillator integrated inside, and the crystal is not well integrated, so it has to be externalized.

Active crystals are much more expensive than passive crystals, but active crystals do not require external circuits.

Compared with passive crystal oscillators, active crystal oscillators are much more stable and can simplify the circuit.

Active crystal oscillators do not require an internal oscillator for DSP, and typically use a PI-type filter consisting of a capacitor and inductor.

The crystal oscillator is equivalent to a human heart in the circuit, and the crystal oscillator provides a clock signal for the circuit.

Active crystal oscillators are more expensive, but active crystal oscillators can vibrate on their own.

Whether it is passive crystal oscillator or active crystal oscillator, it has its own advantages and disadvantages, if you consider the cost of the product, it is recommended to choose a passive crystal oscillator circuit; If the product performance is considered, it is recommended to choose the active crystal oscillator circuit, which is time-saving and convenient to ensure the product performance.

The highest accuracy of the passive crystal oscillator is 5ppm, while the accuracy of the active crystal oscillator can be achieved. The higher the accuracy, the better the frequency stability.

The active crystal oscillator is better than the passive crystal oscillator in terms of stability, but it also has its own small defects, and the signal level of the active crystal oscillator is fixed, so it is necessary to choose the appropriate output level, and the flexibility is poor.

The active crystal oscillator generally has 4 pins, one power supply, one ground, one signal output, and one NC (empty pin).

There is a dot marked with pin 1, and press counterclockwise (pin down) respectively.

The passive crystal oscillator has 2 pins, which need to use an external clock circuit (connected to the ** circuit inside the main IC) to generate an oscillation signal, and cannot oscillate by itself.

1. Passive crystal oscillator:The crystal passive crystal oscillator has 2 pins, and it needs to use an external clock circuit (connected to the ** circuit inside the main IC) to generate an oscillation signal, and it cannot oscillate by itself. A circuit consisting only of resistor-capacitance elements is called a "passive circuit".

2. Active crystal oscillator:An active crystal oscillator is called an oscillator. There are 4 pins and it is a complete oscillator in which, in addition to the quartz crystal, there are transistors and resistor-capacitance elements.

Only a power supply is needed to output a good waveform. In electronics, circuits containing transistor components are often referred to as "active circuits" (such as active speakers, active filters, etc.) and are therefore large.

An active crystal oscillator simply combines a passive crystal with an oscillating circuit.

The most straightforward way is to see if you need a separate power supply, and the one that needs to be powered is active. For example, the general quartz crystal oscillator is passive; And silicon oscillator, Zhong Zhen is active, generally active frequency accuracy is higher, of course, **naturally more expensive to electronic components network** to view the answer details".

Judging from the appearance, in general, there are two pins of passive crystal oscillator, and active crystal oscillator is generally four pins later.

In terms of appearance, the active crystal oscillator is thicker than the passive crystal oscillator, and the printing is much more complicated.

1. Passive crystal oscillator needs a resonant circuit to work, like a single-chip microcomputer, it is equipped with a resonant circuit inside its pin, you only need to connect the crystal oscillator and load capacitor, and power on. This kind of resonant circuit is relatively simple, and the most typical is composed of NAND gate and crystal oscillator.

2. The measurement of crystal oscillator requires a special method, you must have an oscilloscope with sufficient frequency, 20MHz, at least an oscilloscope above 40m, hit the X10 on the probe, pull out the trench, tap the crystal oscillator pin with the core inside, adjust the oscilloscope, and you can see the sine wave waveform. This is the best sign of crystal oscillation. Of course, single-chip microcomputers and the like can also be used to run the program directly, generally speaking, the possibility of crystal oscillator damage is extremely small.

3. Of course, it cannot be measured with a frequency meter, and the voltage on the crystal oscillator is extremely small, and it cannot be seen if there is a slight disturbance. In the previous method, if you don't hit x10, you can't see it.

4. For some things that are more troublesome to test, you can use the substitution method. That is, if you replace another crystal oscillator with the same specification, it is very rare for two crystal oscillators to be damaged at the same time, if you can't get out of it, you have to wonder if your crystal oscillator is matched with the chip, or there is a problem with the chip.