Guidelines for the use of quartz crystal oscillators
　　1 Choose the standard quartz crystal from a manufacturer with proven quality, high reliability, promising development, and good reputation through practice. Obsolete or inferior quartz crystals cannot be used.
　　2 The technical functions, quality levels, and operating conditions of the quartz crystal oscillator should meet the requirements of the planning circuit.
　　3 In the case of satisfactory functional parameters, a quartz crystal with low power consumption, low thermal resistance, low loss angle, high power gain, and high efficiency should be selected.
　　4 The best choice of domestic quartz crystal oscillator. The first choice is the quartz crystal that has passed the certification and conforms to the national standard; the quartz crystal that can be supplied stably through the test and meets the requirements; Youcheng advises to use other quartz crystals that meet the requirements.
　　5Imported quartz crystal oscillator. Quartz crystals in the PPL and QPL (Qualified Product List) of foreign authoritative organizations; high-quality quartz crystals that have been strictly selected during the production process; high-quality quartz crystals that meet the requirements through domestic use inspections.
　　How to use quartz crystals Quartz crystals are preferred, which fits the type of preferred manual or the preferred single PPL issued by a foreign authority. Planners should draw up accurate and clear technical standards for the acquisition of quartz crystal oscillators. In order to ensure the reliability requirements, the standards should be clearly selected (including secondary selection) and quality consistency inspection measures and methods. At the same time, a purchase order for qualified quartz crystal oscillators should be drawn up according to the type regulations. The factors affecting the reliability and quality of quartz crystal oscillators must be clear in the purchase list, such as quality level, environmental conditions, power loss, technical standards, packaging forms, special requirements (antistatic characteristics, temperature scale, etc.), manufacturers, etc. The acquisition standards shall be implemented after approval as required. After the application of the quartz crystal oscillator in the product is confirmed, its reliability should be estimated, and it should be considered whether it is satisfied with the circuit's requirements for the reliability of the quartz crystal oscillator.
　　Derating planning in the use of quartz crystal oscillators Derating planning is to make the stress (electrical stress, temperature stress, mechanical stress, etc.) of the quartz crystal used in electronic products lower than the rated value of its planning, so as to delay the quartz crystal oscillator Parameters are aging, working life is added, and reliability is improved.