UM1 Thru-Hole Crystal Quartz · HMI - BCE SRL

A quartz crystal (crystal or Xtal) is a resonant element made by using the piezoelectric effect of a quartz crystal, which is a quartz wafer with electrodes and a housing package.It is also known as quartz oscillator or crystal resonator.It is a passive component with no active components and requires an external circuit to generate oscillation.This is a passive component,also known as a passive crystal resonator in China.If IC is compared to the brain of human body, then crystal resonator is like the heart of the brain.

Generally speaking we divide crystal oscillators into resonators and oscillators, also known as passive and active crystals,the abbreviation is usually used XTAL and OSC to indicate,this article I mainly talk about passive resonators,and passive resonators we are usually divided into SMD and DIP two different types.For many buyers,they also need to know more about the resonator knowledge,the following I will write 16 specific parameters about the resonator,so as to help buyers better understand the product, the correct understanding and purchase the product,write this article is only my entry into the industry of a self-learning,the knowledge written are some of the most basic parameters of the product, if there are individual errors, please advise Correction.

1.Size

&#; Common SMD crystal model (passive): SMD SMD SMD SMD SMD SMD SMD, this naming we are based on its a length and width of the size, so named, such as SMD, then its length is 1.6mm, width is 1.2mm, due to its appearance is For example, SMD, then its length is 1.6mm, width is 1.2mm, because its appearance is smooth and no corner, we call it SMD. 

&#; Common inline crystal model (passive): HC-49S HC-49SG HC-49SMD HC-49U UM-1 UM-5, we also call it DIP type, because it is relatively larger than SMD type products and has several more leads, so we call it inline type crystal.

&#; Common cylindrical crystal type (passive): what we usually call 3*8 2*6, this type of product is not commonly used now and gradually withdrawn.

2.Frequency Range

This refers to the frequency specified in the crystal component specification, i.e.,the ideal operating frequency desired by the user during circuit design and component selection.For resonator frequency determination also needs the customer's own product on the application, through the customer's own R & D team matching and testing,the customer itself through the R & D test team will give a definite frequency.

3.Load Capacitance (CL)

The effective external capacitance that determines the load resonant frequency FL together with the crystal element. The CL in the crystal element specification is a test condition as well as a condition of use, and this value can be adjusted appropriately according to the situation in the specific use of the user to fine-tune the actual operating frequency of the FL (i.e.the manufacturing tolerance of the crystal can be adjusted).

4.Frequency Tolerence At 25&#;

The maximum allowable deviation of the operating frequency relative to the nominal frequency at the reference temperature.It is often expressed in ppm.

5.Frequency Stability Over Temperature Range

The allowable deviation of the operating frequency in the whole temperature range relative to the working frequency at the reference temperature. Commonly expressed in ppm.

6.Aging Rate

It refers to the frequency drift caused by time under the specified conditions.This indicator is necessary for precision crystals, but it does not have clear test conditions,but by the manufacturer through the continuous supervision of all products with planned sampling,some crystal components may be worse than the specified level, which is allowed.The best solution to the aging problem can only be found in close consultation between the manufacturer and the user.

7.Resonance Resistance (RR)

The equivalent resistance of the crystal element at the resonant frequency is approximately equal to the so-called dynamic resistance R1 or equivalent series resistance (ESR) of the crystal when the effect of C0 is not considered.This parameter controls the quality factor of the crystal element and determines the oscillation level of the crystal in the applied circuit,thus influencing the stability of the crystal and whether it can oscillate ideally.Therefore,it is an important indicator parameter of the crystal element.In general,the smaller the frequency of the crystal chosen for a given frequency,the higher the average value of ESR may be.

8.Load Resonance Resistance (RL)

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Refers to the resistance of the crystal element in series with the specified external capacitor at the load resonant frequency FL.For a given crystal element,the value of its load resonance resistance depends on the value of the load capacitance working with the element,and the resonance resistance after the series load capacitance is always greater than the resonance resistance of the crystal element itself.

9.Resonant Frequency (FR)

Refers to the lower of the two frequencies at which the electrical impedance of the crystal element is resistive under specified conditions. According to the equivalent circuit, when the effect of C0 is not considered,the FR is determined by C1 and L1 and is approximately equal to the so-called series resonant frequency.

10.Load Resonant Frequency (FL)

Refers to one of the two frequencies when the crystal element is connected in series or parallel with a load capacitor under specified conditions and its combined impedance is presented as resistive.When the load capacitor is connected in series,the FL is the lower of the two frequencies;when the load capacitor is connected in parallel,the FL is the higher of the two frequencies.For a given value of load capacitance (CL),the two frequencies are the same for practical effect;and this frequency is the actual frequency that the crystal exhibits in the circuit for most applications,and is the test parameter that the manufacturer uses to meet the user's requirements for the product to meet the nominal frequency.

11.Static Capacitance(CO)

Equivalent circuit capacitance in the static arm.Its size mainly depends on the electrode area,wafer thickness and wafer processing technology.

12.Dynamic capacitance (C1)

The capacitance in the dynamic arm of the equivalent circuit.Its size mainly depends on the electrode area,in addition to the parallelism of the wafer and the size of the trim amount.

13.Level Of Drive

It is a measure of the excitation conditions applied to the crystal element, expressed in terms of dissipated power.

14.SPDB

The difference of parasitic frequency compared to the main frequency level when measured with 12.5ohm test head.

15.DLD2

The difference between the maximum value and the minimum value of the load resonance resistance at different excitation levels.

16.RLD2

The maximum Rr value under different excitation power.

Of course,there are many more parameters of the quartz crystal,but for us to just master the above will do, for most purchases at present,have clearly obtained especially the information of the first seven parameters above,the information of these first seven parameters is also the information that many purchases are looking for when buying,for professional and technical people,they will know more knowledge of the parameters,so this article is also just for the general public, finally thank you for reading.

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