Tech Talk

ICS has published an application note, MAN05, on their website. This application note answers many of the technical questions often asked by our customers.

The custom Ecliptek crystals are quartz crystals designed for use in single chip IC VCXO applications. The crystal devices are AT cut fundamental mode quartz crystals housed in HC-49/U or UM-1 resistance welded packages. The crystals utilize custom quartz resonator designs for improved VCXO performance.

It is recommended that you read the ICS application note MAN05 to obtain a better understanding of the circuit operation. The performance of the VCXO solution is a function of the ICS VCXO and the custom Ecliptek crystal. The quartz crystal is used as the frequency reference of the VCXO. It is important that the crystal used in conjunction with the VCXO meets all required ICS specifications.

Although mechanically similar to standard Ecliptek EC, EU, and E1M series products, there are major electrical performance differences between these two product design types. The most significant of these differences is the capacitive C0/C1 ratio (r) and the elimination of undesired vibrational modes and frequency perturbations. These items are not specified on the standard Ecliptek EC, EU, and E1M series products. Ecliptek uses exclusive crystal processing methods and proprietary design techniques that enable the crystal to meet the custom crystal requirements needed for operation with the ICS VCXO IC.

The ICS VCXO IC devices and the custom Ecliptek crystals are commonly used in the following products:

• Set-Top Box, Digital TV, MP3 Players
• MPEG Video Equipment
• Telecom and Network Synchronization Equipment
• Optical and High-Speed Networking Equipment
• Digital Switching Network Equipment
• SONET/ATM/SDH System Equipment

These crystals and IC's are used in many of the following applications:

• Clock Recovery
• Phase-Locked Loops (PLL's)
• Frequency Multiplication
• Jitter Attenuation

• Frequencies from 8.192MHz to 28.321MHz
• Custom quartz resonator designs for improved performance
• AT Cut Fundamental Mode Crystal Oscillation
• Low crystal resistance for improved jitter and phase noise performance
• Low r ratio performance for increased VCXO frequency pullability
• Special quartz designs for the elmination of undesired vibrational modes and frequency perturbations (also known as activity dips)
• Commercial and industrial temperature ranges
• Tape and Reel Packaging
• Value Added Options such as Custom lead lengths, Multiple SMD gull wing configurations, Insulator tabs, Third leads, and Vinyl sleeving

A listing of the Ecliptek custom crystal part numbers (ECX prefix) can be found on the ICS Approved VCXO Crystals listing.

A copy of the Ecliptek custom crystal part number specification (ECX prefix) can be obtained from your Ecliptek Sales Representative.

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The existing custom crystal approved by ICS cover the frequency range of 8.192MHz to 28.321MHz. Only specific frequencies within this range have been approved by ICS. If a particular desired frequency is not listed on the ICS Approved VCXO Crystals listing, please contact us or ICS with your custom requirement.

Using a packaged quartz crystal clock oscillator to drive the VCXO IC's listed on MAN05 is not approved by ICS. These VCXO IC products require frequency modulation or "pulling" of an external crystal.

The HC-49/U and UM-1 packages, with their round plano resonators, are the only package configurations approved by ICS for use with the ICS VCXO IC's specified in the ICS Approved VCXO Crystals listing. The use of rectangular "strip" resonators in both through-hole and SMD packaging are not approved by ICS.

The HC-49/U and UM-1 packages, with their round resonators, are the only packages configuration approved by ICS for use with the VCXO IC's as specified in the ICS Approved VCXO Crystals listing. The use of an SMD quartz crystal (i.e. Ecliptek EC2SM, EC3SM, EC4SM, or ECCM1 Series) incorporating a "strip" resonator quartz crystal is not approved by ICS.

The HC-49/U package can be produced in two different SMD configurations by Ecliptek. These value added options include the "G" and the "G3" options. The "G" option consists of an HC-49/U crystal with the addition of a third lead on the top of the package. All three crystal leads are then lead formed into an SMD gull wing configuration prior to shipment. The "G3" option consists of an HC-49/U crystal with the addition of an SMD metal jacket on the top of the package. The two crystal leads are then lead formed into an SMD gull wing configuration prior to shipment.

The recommended solder pad layout for the "G" and "G3" options can be found in the value added options section of our website.

The value added options offered by Ecliptek include: Custom lead lengths (CLXXX options), Insulator tabs (I2 option), Third leads (L and L2 options), and Vinyl sleeving (V option).

The through-hole HC-49/U and UM-1 crystal packages consist of a round AT cut quartz crystal resonator mounted onto a crystal base. Electrodes on each side of the quartz wafer connect to the crystal base leads through the use of high temperature conductive epoxy. The leads of the base are isolated from the base itself using glass-to-metal seals. A cover is placed over the crystal and base assembly and is hermetically sealed with a vacuum resistance weld process.

The "pull range" parameter is a VCXO specification, not a crystal specification. The custom Ecliptek ECX specification does not specify the "pull range" parameter. Ecliptek specifies the "r" ratio, defined as the C0/C1 ratio (See figure 1 below). This ratio is defined as the crystal shunt capacitance divided by the crystal motional capacitance. This method of specification is outlined in MAN05 and is a method of expressing the crystal attributes that control VCXO frequency pullability. As shown in figure 1, the change in frequency decreases as the r ratio increases (assuming a fixed load capacitance, C_L) for a parallel resonant crystal.
Figure 1: Frequency vs. Load Capacitance

The use of BT cut fundamental mode crystals is not approved by ICS. The reason for this is the resultant high r ratio of BT cut crystals. This is due to the low C1 values that are typical of BT cut resonators. AT crystals are the only approved cuts for use in the ICS VCXO IC applications as specified in MAN05.

Frequency tolerance, often called calibration accuracy, is the amount of frequency deviation from a specified center frequency at ambient temperature (referenced at 25°C). This parameter is specified with a maximum and minimum frequency deviation, expressed in percent (%) or parts per million (ppm).

This parameter can be found on the respective custom Ecliptek part number specification sheet. This parameter is typically ±20ppm for the custom Ecliptek crystals used with ICS VCXO IC's.

Frequency stability is the amount of frequency deviation from the ambient temperature frequency over the operating temperature range. This parameter is specified with a maximum and minimum frequency deviation, expressed in percent (%) or parts per million (ppm). The frequency stability is determined by the following primary factors: Type of quartz cut and angle of the quartz cut. Some of the secondary factors include: mode of operation, drive level, load capacitance, and mechanical design.

This parameter can be found on the respective custom Ecliptek part number specification sheet. This parameter is typically ±30ppm for the custom Ecliptek crystals used with ICS VCXO IC's.

Ecliptek offers products in the commercial temperature range of 0°C to +70°C and the industrial temperature range of -40°C to +85°C.

Aging is the systematic change in frequency with time due to internal changes in the crystal and/or oscillator. Aging is often expressed as a maximum value in parts per million per year [ppm/year]. The rate of aging is logarithmic in nature. The following factors effect crystal aging: adsorption and desorption of contamination on the surfaces of the quartz, stress relief of the mounting and bonding structures, material outgassing, and seal integrity. At a rated operating temperature of 25°C, these custom crystal products typically age at a rate of ±3ppm over the first year, ±1ppm over the following year, logarithmically declining each year thereafter. The aging parameters for each product can be found on the applicable specification sheets.

Ecliptek does not use inverted mesa technology on the crystal part numbers approved by ICS. The need to produce a fundamental mode crystal using inverted mesa technology is typically needed for crystals over 35MHz. Please contact us if you have custom requirements regarding the crystal technology used.

If the part number is specified with the TR option, the crystals are delivered to the customer in a through-hole configuration with EIA468B compliant tape and reel packaging. If the part number is specified with the G3 - TR4 option, the crystals are delivered to the customer with the "G3" SMD option configuration with EIA481A compliant tape and reel packaging. All other package configurations are shipped bulk in ESD safe bags. All of these crystal products are capable of withstanding industry standard high temperature convection reflow processes and each specification on the Ecliptek website includes a suggested solder reflow diagram.

The "Environmental and Mechanical Specifications" for each product type is listed on the applicable Ecliptek crystal specification.

Failure in Time (FIT) and "Mean Time To Failure" (MTTF) reliability data is available from the factory. Please contact us with your request for this data.

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Find a representative or distributor and request the custom Ecliptek ECX part number referenced in the ICS Approved VCXO Crystals listing. You can also contact the Ecliptek sales staff directly at the factory.

The engineering staff at Ecliptek can provide applications engineering support for customer technical questions.

Due to the original release date of these items, many of the custom Ecliptek ECX part number referenced in the ICS Approved VCXO Crystals listing are not RoHS compliant or Pb-free. However, today, Ecliptek is capable of manufacturing RoHS compliant (Pb-free) equivalents to all of these part numbers. Please contact the Ecliptek sales staff directly at the factory for your specific RoHS compliant part number request.

A RoHS product certification letter can be obtained directly from our website by using our Ecliptek RoHS Certification Letter Generator.