Q: Do passive crystals need power?

A: Crystals from different manufacturers can be interchangeable when their key electrical parameters and package requirements are compatible. In particular, frequency, load capacitance (CL), equivalent series resistance (ESR), and frequency tolerance should be considered when evaluating a replacement. The PCB footprint and package size also need to match the design.

Smaller packages can replace larger ones when the PCB footprint is redesigned, while differences in ESR may require attention to the MCU’s driving capability. For applications with higher reliability requirements, direct substitution should be validated rather than determined only by matching the nominal frequency. Our engineering support includes crystal selection, circuit matching, and sample testing, which can help evaluate whether a specific crystal is suitable for a customer’s circuit. This approach allows replacement decisions to be based on actual electrical and mechanical requirements rather than frequency alone.

A: A “wide temperature” crystal refers to a crystal designed to maintain stable frequency performance across a broader operating temperature range than standard commercial products. In SJK’s product portfolio, different temperature grades are available according to application requirements.

Some SMD crystal series support operating temperatures from -20°C to +70°C, with -40°C to +85°C options available, while automotive-grade crystal products can support operating temperatures extending to -40°C to +125°C. These wider temperature ranges are suitable for applications exposed to demanding environmental conditions, including automotive and industrial electronics. SJK also offers crystal products with different frequency tolerances, load capacitances, and drive levels, allowing the specifications to be matched to different circuit requirements. When selecting a wide-temperature crystal, the required operating range should therefore be considered together with frequency stability and other electrical parameters to ensure proper compatibility with the target application.

A: When selecting a crystal for an MCU, we recommend focusing on the parameters specified in the MCU datasheet, particularly frequency, load capacitance (CL), maximum ESR, and drive level. These parameters should be compared with our crystal specifications to identify a suitable component for the oscillator circuit. SJK provides crystal units in different frequency categories, including MHz crystals and 32.768 kHz crystals, as well as SMD crystal resonators in multiple package options.

We also offer automotive crystals and various crystal oscillator products. Load capacitance is related to the external capacitor calculation, while drive level is an important parameter for crystal operation. By reviewing the MCU requirements together with our crystal specifications, customers can evaluate whether a selected crystal meets the requirements of their oscillator circuit and intended application.

A: SJK recommends several measures for reducing EMI in crystal and oscillator circuit designs, including shorter signal traces, a damping resistor, shielding, and lower voltage. These measures can be considered as part of the circuit design when addressing electromagnetic interference.

We also provide differential oscillators for high-speed digital applications, supporting industry-standard differential output formats including LVDS, LVPECL, HCSL, and CML. Our differential oscillators feature signal integrity, ultra-low phase jitter, and EMI performance. In addition, our oscillator portfolio includes SPXO, VCXO, TCXO, OCXO, MEMS, and other frequency-control products. When customers select an oscillator, we recommend considering the required frequency, output format, and electrical requirements together with the circuit design and layout to meet the application's frequency-control and EMI requirements.

A: An RTC crystal is a 32.768 kHz quartz crystal used as a frequency reference for real-time clock applications and timekeeping. At SJK, we provide 32.768 kHz crystal products in both traditional cylindrical and SMD packages. Our cylindrical tuning-fork crystals are available in 2×6 mm and 3×8 mm sizes, while our SMD versions include 1610, 2012, 3215, and 7015 packages. We offer load capacitance options of 6 pF, 7 pF, 9 pF, and 12.5 pF, with standard frequency tolerances of ±10 ppm and ±20 ppm.

Our 32.768 kHz crystals are designed for applications requiring low power consumption and stable frequency performance. We also provide RTC-related products, including low-power, temperature-compensated, AEC-Q200 automotive-grade, and ultra-compact SMD solutions for industrial, automotive, IoT, and low-power embedded systems. This product range allows us to support different RTC timing and packaging requirements.