At present, more and more electronic devices are equipped in automobiles. These devices need to communicate through in-vehicle networks (IVNs). Resonators provide a frequency control function in the communication process to ensure stable operation of the system. This article will show you the application of resonators in the automotive field, as well as crystal resonators and ceramic resonators introduced by Murata.
Resonators are widely used in automotive applications
Resonators are electronic components that generate a resonant frequency. Commonly used resonators are mainly divided into quartz crystal resonators and ceramic resonators. Resonators generate frequency and have the characteristics of stability and good anti-interference performance. They are widely used in various electronic products. The frequency accuracy of quartz crystal resonators is higher than that of ceramic resonators, but the cost is also higher than that of ceramic resonators. Resonators mainly play the role of frequency control. All electronic products need resonators for frequency transmission and reception, and resonators can be used as reference clocks or signal sources for electronic circuits.
Quartz crystals can utilize the piezoelectric characteristics of crystal materials to transmit accurate frequency signals to an IC (Microcontroller). Applying electric fields to sputtering deposition electrodes on both sides of a crystal blank will cause vibration in the quartz crystal as a piezoelectric material.
Ceramic resonators use highly stable piezoelectric ceramics mainly composed of Lead-Zirconate-Titanate (PZT) as mechanical resonators. When a voltage is applied, deformation occurs due to the piezoelectric effect and resonance occurs at a specific frequency. The resonance frequency is determined by the vibration mode and the size (length and thickness) of the ceramic substrate.
In automotive applications, there are various cases of using resonator products, including advanced driver assistance systems (ADAS) with a camera architecture and radar architecture, tire-pressure monitoring system (TPMS), remote keyless entry (RKE), Ethernet, wireless charger, NFC (key), general or digital instrument cluster, parking assistance system, surround view camera system, driving recorder, battery management system and motor controller for electric/hybrid vehicles.
The special structural design has superior characteristics
In automotive applications, electronic components must face complex environments such as high temperature, low temperature, vibration, noise, etc. Therefore, the quality requirements for resonators are particularly high. Murata has continuously supplied the market with ceramic resonators (CERALOCK®) as reference clocks for microcomputers, etc, for more than 40 years. In order to meet the demand for devices with a higher precision clock where the frequency accuracy of ceramic resonators cannot be supported, small crystal resonators with high reliability have been jointly developed with Tokyo Denpa Co., Ltd. Murata has supplied products to the consumer market since 2009 and to the automotive market since 2013.
Murata's crystal resonator uses a unique package technology where the existing crystal resonator does not have and is characterized by superior quality, mass production, and high cost performance. Compared with ordinary crystal resonators that use a cavity ceramic package, Murata's crystal resonator uses the combined structure of planar alumina substrate and a metal cap with many years of proven market performance in ceramic resonators. By adopting the universal highly planar alumina substrate and metal cap, the material cost can be reduced while the supply stability and the corresponding ability of increasing production can be improved compared with traditional crystal resonators.
Murata has a one-stop system from the production and design of raw crystal stones and the production of original equipment to its global sales network. Therefore, it has a unique manufacturing process and can explore new fields to provide new value for customers.
Automotive crystal resonators meet in-vehicle reliability requirements
Murata's automotive crystal resonators (XRCHA series, XRCGB series, XRCGE series) have Murata's unique package technology, with superior quality, mass production and cost performance, and can correspond to the next-generation of in-vehicle communication standards, i.e. in-vehicle Ethernet/FlexRay. When it is used as an in-vehicle Ethernet/FlexRay, the overall accuracy can reach ±50ppm, and the load capacity (Cs) can correspond to 6pF, 8pF, 10pF, etc.
Murata's automotive crystal resonator can meet the reliability guarantees required (AEC-Q200) for in-vehicle use. It can be placed at high temperatures up to +125℃ for 1000 hours, for 1000 temperature cycles, each from -55℃ to +125℃, with a biased humidity load up to +85℃, 85% humidity, DC6V for 1000 hours, with a high temperature exposure up to +125℃ and DC6V for 1000 hours.
Murata's automotive crystal resonator is available in a compact and highly reliable package, which is suitable for the ECU downsizing of 2.5×2.0mm/2.0×1.6mm, realizing a maximum of 60% downsizing capabilities compared with the size of 3.2×2.5mm. With the high-reliability package used in CERALOCK, it has superior mechanical properties such as impact resistance, drop shock resistance, and weather resistance. With no omission of vibration suppression particles, Murata's original particle screening technology can accurately identify defective products with particles attached and possibly causing a deterioration of crystal resonator characteristics at the production stage, and introduce a shape design suitable for automatic optical inspection (AOI), adopting a compact size angle electrode shape that can improve the visibility of solder fillets.
XRCGB40M000F5A00R0
Murata's small automotive crystal resonators (2.0x1.6x0.7mm) include XRCGB_F_A, XRCGE_F_A, XRCGB_F_C, XRCGB_F_G (for infotainment purposes) series.
Fast oscillation startup time of automotive ceramic resonators
Murata's CERALOCK ceramic resonators for automobiles (XRCHA series, XRCGB series) are widely used in automotive applications. These automotive products are used by customers around the world and are rooted in the design and manufacturing technologies developed by Murata over the years. CERALOCK ceramic resonators are helpful in simplifying the design and can realize compact, low-profile and built-in capacitance product design, and reduces the number of components. It is suitable for the frequency accuracy of CAN communication. The total frequency tolerance for LS-CAN is ±0.8% (total frequency tolerance varies by product series), and the total frequency tolerance for HS-CAN is ±0.27%.
Murata's CERALOCK ceramic resonator for automobiles has a fast oscillation startup time. The oscillation startup time means the time required to move from the oscillation transient state to the constant area when the IC is activated. Murata requires a startup time up to 90% of the oscillation level under steady state conditions. The oscillation startup time is affected by the components used in the oscillation circuit. Compared with the crystal resonator, the oscillation startup time of CERALOCK will be more than 10 times faster.
In order to meet the reliability suitable for the powertrain system/chassis and the functional environment such as “driving, turning, and stopping”, CERALOCK ceramic resonators can be placed at high temperatures up to +125℃ for 1000 hours, for temperature cycles, each from -55℃ to +125℃, with a biased humidity load up to +85℃, 85% humidity, DC6V for 1000 hours, with a high temperature exposure up to +125℃ and DC6V for 1000 hours.
In order to respond to the diverse specification requirements, Murata offers products of various frequencies that meet customer requirements within the frequency range of various series, and adds 150℃ corresponding products to the product lineup. CSTCR_G_B (frequency 4.00 ~ 7.99 MHz), CSTNE_G_A (frequency 8.00 ~ 13.99 MHz), and CSTNE_V_C (frequency 14.00 ~ 20.00 MHz) are introduced for general automotive applications, with the frequency tolerance of ±0. 5%. CSTNR_GH5C (frequency 4.00 ~ 7.99 MHz), CSTNE_GH5C (frequency 8.00 ~ 13.99 MHz), and CSTNE_VH3C (frequency 14.00 ~ 20.00 MHz) are introduced for in-vehicle network applications (high precision components), with the frequency tolerance of ± 0.07%.
Conclusion
Resonators are widely used in various electronic products. Facing the harsh environments of automotive applications, high-quality resonators have an important influence on the stability of products. Murata has decades of resonator manufacturing experience and patented technology, which can meet the stringent requirements of automotive applications and will be the best choice and partner for relevant product developers.
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