Question 1

Q: Are OCXOs suitable for battery-powered applications?

Accepted Answer

A: Our OCXOs are generally not suitable for battery-powered applications because their power consumption can drain a battery quickly. Where an application requires both OCXO performance and reduced power requirements, a specialized low-power model, such as a miniature OCXO, can be considered. SJK provides multiple oscillator technologies for different power and performance requirements. Our SPXO products feature low power consumption and ultra-low operating voltage down to 1.8 V, while our TCXO products also emphasize low power consumption.

We also provide 32.768 kHz crystal and RTC products for low-power timing applications. Our RTC portfolio includes low-power solutions for IoT and low-power embedded systems, with 3V operating current as low as 45 nA for our listed RTC products. For battery-powered designs, customers can therefore evaluate our low-power frequency-control products according to the application's required performance and power conditions.

Question 2

Q: How does an OCXO compare with an atomic clock?

Accepted Answer

A: An OCXO and an atomic clock are both used as high-precision frequency references, but they are based on different technologies and serve different levels of timing requirements. An OCXO uses oven-controlled quartz technology to maintain the crystal resonator at a controlled temperature, reducing frequency changes caused by environmental temperature variations. SJK’s OCXO products provide frequency accuracy of up to ±3 ppb / ±10 ppb and are designed for applications requiring highly stable timing and frequency references.

SJK also lists atomic clock reference systems among the typical application areas for its OCXO products, showing that OCXOs can be used as part of high-precision timing systems. Compared with atomic frequency references, an OCXO is a quartz-based solution that combines high stability with relatively compact SMD and DIP package options. The appropriate choice ultimately depends on the required frequency accuracy, stability, application environment, and system design.

Question 3

Q: Do AI data centers use OCXOs?

Accepted Answer

A: Yes. In network synchronization switches using SyncE/PTP, OCXOs are a core component for clock holdover. At SJK, we identify AI and computing as important application areas for our crystal oscillator technology. Our application materials describe crystal oscillators as reference clocks for AI systems, where real-time data processing, low-latency decision-making, and communication stability are important requirements. We also manufacture high-precision OCXO using oven-controlled technology to isolate quartz crystal resonators from external temperature variations.

Our OCXO products are designed to provide extremely high frequency stability and excellent low phase noise performance. This makes OCXO technology part of our frequency-control solutions for high-precision timing requirements. Our broader oscillator portfolio also includes differential oscillators for high-speed digital applications and TCXO for applications requiring frequency accuracy and temperature stability.

Question 4

Q: What applications require an OCXO?

Accepted Answer

A: OCXOs are intended for applications that require a highly stable frequency reference and precise timing performance. SJK’s OCXO products use oven-controlled technology to isolate the quartz crystal resonator from external temperature variations, providing high frequency stability and low phase noise. The SJK OCXO range covers output frequencies from 5 MHz to 100 MHz, with frequency accuracy of up to ±3 ppb / ±10 ppb depending on the product.

Typical applications listed by SJK include base station communication systems, precision test and measurement equipment, satellite navigation systems, high-precision clock synchronization networks, telecommunication infrastructure, and frequency standard equipment. OCXOs are therefore more suitable for systems where frequency stability is a key requirement rather than for basic clock applications. SJK offers multiple supply voltages, package options, and output formats, as well as customized frequency and specification solutions for different high-precision timing requirements.

Question 5

Q: What is drive level?

Accepted Answer

A: Drive level refers to the power consumed by a crystal during operation. It is an important parameter because the crystal needs to operate within its specified drive-level range. If the applied drive level exceeds the recommended limit, the crystal may be damaged or its long-term performance may be affected. SJK specifies drive-level requirements for different crystal products according to their design and frequency range.

Some SMD crystal series have a typical drive level of 100 μW, while automotive crystal products can offer different drive-level options such as 10 μW, 100 μW, and 200 μW or customized specifications. When selecting a crystal, the drive level should therefore be checked together with frequency, load capacitance, ESR, and other circuit parameters. SJK also supports circuit matching and product selection, helping customers evaluate the appropriate crystal specifications for their designs.

Question 6

Q: Do active oscillators need decoupling capacitors?

Accepted Answer

A: Yes. A decoupling capacitor is recommended for active oscillators to help maintain a stable power supply and reduce noise around the oscillator. A commonly used value is 0.1 μF, placed as close as possible to the oscillator’s VCC pin. Keeping the capacitor close to the power pin helps minimize noise along the power-supply path and supports stable oscillator operation. The capacitor should be considered during the circuit design stage rather than added only after the PCB has been completed. The specific power-supply arrangement should also be checked against the electrical specifications of the selected oscillator and the requirements of the target circuit.

For customers working on a new design or replacing an existing timing component, SJK provides technical support covering component selection and circuit matching. This allows the power-supply design, component specifications, and application requirements to be considered together during the selection process. For projects with specific circuit conditions, our technical team can also assist with evaluating the suitability of the selected component before production.

Question 7

Q: Do passive crystals need power?

Accepted Answer

A: Passive crystals do not require a separate power supply. They work together with the oscillator circuit inside the MCU, where the crystal acts as the frequency-determining component of the circuit. This differs from an active oscillator, which integrates the oscillator circuit and provides a clock output as a powered device. SJK supplies both crystal resonators and crystal oscillators for different circuit designs.

Our crystal unit portfolio includes MHz crystal units, 32.768 kHz crystals, and automotive crystal products, while the oscillator range covers SPXO, VCXO, TCXO, OCXO, MEMS, differential, and other oscillator types. For passive crystal applications, parameters such as frequency, load capacitance, ESR, and drive level need to be considered together with the MCU design. SJK also provides circuit matching and oscillator selection support, helping customers select the appropriate frequency component according to their circuit and application requirements.

Question 8

Q: Can crystals from different brands be interchangeable?

Accepted Answer

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.

Question 9

Q: What is a “wide temperature” crystal?

Accepted Answer

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.

Question 10

Q: How to select a crystal based on the MCU datasheet?

Accepted Answer

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.

Question 11

Q: How to reduce EMI?

Accepted Answer

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.

Question 12

Q: Can MEMS replace quartz?

Accepted Answer

A: MEMS can replace quartz in some frequency-control applications, but the appropriate technology depends on the required performance characteristics.

MEMS performs better in shock resistance and lead time, while quartz excels in phase noise and frequency stability. We provide both MEMS oscillators and quartz-based crystal units and oscillators in our frequency-control portfolio. This allows us to address different design requirements rather than treating one technology as a universal replacement for the other.

Our product portfolio emphasizes miniaturization, high precision, and low power consumption, with frequency-control solutions for various electronic applications. When customers compare MEMS with quartz, we recommend evaluating the characteristics required by the intended design, including the balance between shock resistance, lead time, phase noise, and frequency stability, before selecting the appropriate technology.

Question 13

Q: What is RTC crystal?

Accepted Answer

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.

Question 14

Q: What is AEC-Q200 certification?

Accepted Answer

A: AEC-Q200 is a reliability standard for passive electronic components developed by the Automotive Electronics Council. It defines a series of qualification requirements for components used in demanding automotive environments, including conditions involving temperature, humidity, mechanical shock, and vibration. SJK automotive-grade crystals have passed AEC-Q200 certification and are designed to meet the reliability requirements of vehicle electronic systems.

The qualification process includes strict reliability testing.

Temperature cycling is conducted from -50°C to +150°C for 1,000 cycles to verify that the package remains free from cracks, leakage, and structural damage.

Mechanical shock and vibration testing simulates harsh driving and road-impact conditions.
Humidity and heat testing is conducted at 85% humidity and +85°C for 1,000 hours to evaluate electrical performance stability.
Hermeticity, lifetime, and other reliability tests are also included in the qualification process.

For customers evaluating frequency components for automotive electronics, AEC-Q200 is therefore an important qualification to consider when assessing component reliability and suitability for demanding vehicle environments.

Question 15

Q: How to calculate external capacitors?

Accepted Answer

A: We calculate the external capacitors using the formula C1 = C2 = 2 × (CL - Cs), where CL is the required load capacitance and Cs represents parasitic capacitance. The parasitic capacitance is typically 3–5 pF. When selecting external capacitors for a crystal oscillator circuit, we recommend considering the required load capacitance specified for the crystal together with the oscillator circuit requirements.

At SJK, we provide crystal units for different electronic designs, including MHz crystals and 32.768 kHz crystals, as well as SMD crystal resonators in multiple package sizes. Our product portfolio supports frequency-control requirements with a focus on high precision, miniaturization, and low power consumption. By matching the crystal's load capacitance with the circuit design and calculating the external capacitors accordingly, engineers can select a suitable configuration for their application.