Temperature-Compensated Crystal Oscillators – TCXO’s

Suntsu TCXO’s and VCTCXO’s are available in through-hole or surface-mount packaging with many sizes to choose from. We offer many different voltages and can provide parts with Stratum 3 compliancy. Pick out a standard part number from the data sheets listed below or contact our sales team to request any custom parameters that you may require and we will design to your specific needs.

Temperature-Compensated Crystal Oscillators use sampling techniques to correct the temperature deficiencies of a crystal oscillator circuit, its package and its environment. Typically the correction techniques involve the physical and electrical characterization of the motional inductance and terminal capacitance of the crystal blank. The knowledge of which is used to create a correction polynomial, or algorithm, which in turn is implemented in circuit blocks and maintains better stabilities than standard oscillators.

SeriesImageLogicPackageStability ToVoltage(s)FrequencyReelKey FeatureDatasheet
STC22KCLIPPED SINE WAVE2.5X2.0 CERAMIC SMD (4 PAD) (VC)TCXO±0.5ppm1.8V, 2.5V, 2.7V, 3.0V, 3.3V13.000MHz-52.000MHz3KUltra-Miniature Package, High Stability
STC32CCMOS3.2X2.5 CERAMIC SMD (4 PAD) (VC)TCXO±1.0ppm2.5V, 2.7V, 3.0V, 3.3V6.000MHz - 40.000MHz3KUltra-Miniature Package
STC32KCLIPPED SINE WAVE3.2X2.5 CERAMIC SMD (4 PAD) (VC)TCXO±0.5ppm1.8V, 2.5V, 2.7V, 3.0V, 3.3V6.000MHz - 40.000MHz3KUltra-Miniature Package, High Stability
STC53CCMOS5.0X3.2 CERAMIC SMD (4 PAD) (VC)TCXO±1.0ppm2.5V, 2.7V, 3.0V, 3.3V6.000MHz - 40.000MHz3KMiniature Package
STC53KCLIPPED SINE WAVE5.0X3.2 CERAMIC SMD (4 PAD) (VC)TCXO±1.0ppm2.5V, 2.7V, 3.0V, 3.3V6.000MHz - 40.000MHz3KMiniature Package
STC75CCMOS7.0X5.0 CERAMIC SMD (10 PAD) (VC)TCXO±0.5ppm3.3V, 5.0V5.000MHz - 40.000MHz1KMiniature Package, High Stability
STC75KCLIPPED SINE WAVE7.0X5.0 CERAMIC SMD (10 PAD) (VC)TCXO±0.5ppm3.3V, 5.0V5.000MHz - 40.000MHz1KMiniature Package, High Stability
SST75CCMOS7.0X5.0 CERAMIC SMD (10 PAD) (VC)TCXO±0.14ppm3.3V, 5.0V5.000MHz-26.000MHz1KStratum 3, Voltage Control
SST75KCLIPPED SINE WAVE7.0X5.0 CERAMIC SMD (10 PAD) (VC)TCXO±0.14ppm3.3V, 5.0V5.000MHz-26.000MHz1KStratum 3, Voltage Control
STCFSCCMOS14 PIN DIP (VC)TCXO±1.0ppm3.3V, 5.0V1.000MHz - 800.000MHzN/AWide Frequency Range
STCFSKCLIPPED SINE WAVE14 PIN DIP (VC)TCXO±1.0ppm3.3V, 5.0V6.000MHz - 200.000MHzN/AWide Frequency Range
SSTFSCCMOS14 PIN DIP (VC)TCXO±1.0ppm3.3V, 5.0V2.000MHz - 40.000MHzN/AStratum 3, Voltage Control
SSTFSKCLIPPED SINE WAVE14 PIN DIP (VC)TCXO±1.0ppm3.3V, 5.0V2.000MHz - 40.000MHzN/AStratum 3, Voltage Control
SST20CCMOS20.0X20.0 DIP (VC)TCXO±1.0ppm3.3V, 5.0V2.000MHz - 150.000MHzN/AStratum 3, Voltage Control
STC21KCLIPPED SINE WAVE2.0X1.6 CERAMIC SMT (6 PAD) (VC)TCXO±0.5ppm1.8V, 2.5V, 2.7V, 3.0V, 3.3V10.000MHz - 52.000MHz3KUltra-Miniature Package
STC11KCLIPPED SINE WAVE1.6X1.2 CERAMIC SMD (4 PAD) (VC)TCXO±0.5ppm1.8V, 2.5V, 2.7V, 2.8V, 3.0V, 3.3V26.000MHz - 52.000MHz3KMiniature Package

Quick Summary

Features Benefit Manufacturing Location(s) Monthly Capacity
• Tight stability performance (down to 0.5ppm) • Stratum 3 options available
• Form factor down to 2.0 x 1.6mm
• Custom configurations available
• China
• South Korea
• >5M units

What Is a TCXO?

A temperature compensated crystal oscillator (TCXO) is a specialized type of crystal oscillator that provides an even higher level of stability and accuracy when required for particular electronic devices. In a standard crystal oscillator unit, oscillation frequency variations occur in response to increases in temperature. This instability of frequency can seriously impair the overall function of the electronic device. Essentially, a TCXO actively counteracts the effect of any temperature variations on the crystal oscillator’s frequency stability. These crystal oscillator units are most commonly found in high-temperature environments.

How Do TCXOs Work?

TCXOs are prized for their frequency stabilization properties, including how they are able to resist and counteract even fairly significant increases in external temperatures. In a TCXO, its temperature compensation network, also known as a thermistor network, identifies temperature changes outside of the specified range and initiates a frequency stability mechanism in response. The Temperature change causes the thermistors to vary, which causes a change in the equivalent capacitance of network. This in turn changes the capacitance load on the crystal, causing a change in the frequency of the oscillator.

What Are the Advantages of a TCXO?

Even though standard crystal oscillators are valued for their resistance to changes in temperature and maintenance of specified frequencies, they may still be subjected to temperature variations. A TCXO efficiently stabilizes the oscillator’s frequency level in response to temperature changes, which allows this type of crystal oscillator to be used in settings with variable temperatures without sacrificing performance or incurring significant operating expenses.

What Are the Common Types of TCXOs?

Distinctions between the common types of TCXOs are based on the type of mechanism that each oscillator uses to counteract temperature changes. The most common types of TCXOs include the analog digital TCXO, digital TCXO, DCXO and MCXO.

TCXO vs. VCTCXO

A voltage-controlled temperature compensated crystal oscillator (VCTCXO) is a type of TCXO that maintains and stabilizes its oscillation frequency by relying on the application of an analog voltage in response to temperature increases. The voltage applied to the VCTCXO is exactly inverse to the temperature change, which maintains the TCXO accuracy.

TCXO Solutions

A TCXO offers solutions to the primary issues with quartz crystal oscillators, including crystal aging and frequency stability. Instead of encasing the crystal within an oven to protect it, the TCXO identifies temperature changes and stabilizes the frequency through the application of the voltage current at the exact inverse of the variation in temperature. In addition, TCXOs are intended to be recalibrated approximately every six to 12 months, which protects against premature crystal aging. That is why TCXOs are used in high-quality mobile phones, tablets, GPS navigation devices and portable radios.

Temperature Performance of Crystal Oscillators

Crystal oscillators are susceptible to frequency drift in response to prolonged and significant temperature changes outside of their specified range. Even though a crystal oscillator may be able to function temporarily outside of its specified temperature range, it is not recommended for the performance and longevity of the oscillator unit and device.

What Is the Difference Between Oven-Controlled Crystal Oscillators (OCXOs) and TCXOs?

Although oven-controlled crystal oscillators (OCXOs) and TCXOs are both heat-related oscillation devices, a TCXO provides enhanced frequency stability protections against temperature increases and is much smaller than an OCXO. TCXOs are ideal for portable electronic devices that require a stable frequency source.

A. Design

OCXOs are larger than TCXOs and standard crystal oscillators because they require a heater for the oscillator. The TCXO is more compact because it does not operate with an oven and insulation layer. Also, the TCXO may not even require a seal enclosing the oscillator package. The package sizes of the TCXO vary according to their function, but they are relatively small compared to other oscillator options.

B. Power Consumption

OCXOs may consume a significant amount of power because the heater in the OXCO typically requires power from an additional source than the oscillator itself. An increase in the OXCO’s internal temperature after starting up will reduce the amount of power required for operation. In terms of the TCXO circuit design, the additional circuitry needed for a TCXO to sense and respond to temperature results in greater power dissipation than that of a standard oscillator.

C. Calibration

Unlike an OXCO, a TCXO is intended to be reset or recalibrated at regular intervals. The specifications for the individual device will describe the recalibration requirements. This process helps stave off crystal aging, which is an issue for the longevity and stability of other crystal oscillators.

Frequently Asked Questions

The TCXO is the preferred crystal oscillator, especially for portable electronic devices, when it comes to maintaining the stability of its frequency. Its temperature-based stability mechanisms enable constant output of the specified frequency regardless of external increases in temperature.

Crystal oscillators are considered accurate and reliable in their ability to resist external temperature variations and generate a precise frequency. This is especially true in comparison to LC resonator circuits. One of the specialized types of crystal oscillators, a TCXO, provides an enhanced backstop against unwanted frequency changes.

Analog oscillators, also referred to as voltage-controlled oscillators (VCOs), are found in synthesizers and work by generating an AC signal at a specific oscillation frequency as well as a sound. To adjust the frequency of an analog oscillator, an input voltage is required. Due to their sound qualities, VCOs are preferred over digital oscillators for a more natural sound.

The important elements of a TCXO include its compensation network, oscillator pulling circuit, crystal oscillator circuit, voltage regulator and buffer amplifier. The effects of temperature on a crystal oscillator can be minimized according to the shape and cut of the crystal, but a temperature-controlled oscillator offers even greater resistance to frequency changes with the application of a correction voltage to the oscillator based on temperature.

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