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Answers

Q: What does EProClock® mean?

A: It means Electrically Programmable Clock.

EProClock® is a registered trademark for all SpectraLinear programmable clocks. We use EEPROM or OTP (One Time Programmable) memories or serial I2C interface to electrically program SpectraLinear’s products.

 

Q: What does Dial-a-dB® mean?

A: Dial-a-dB® is a registered trademark for all SpectraLinear EMI reduction (SSCG) products. SpectraLinear SSCG products’ spread percent value can be programmed anywhere from 0 to 5.0% as a down or center spread and lead to a 4 to 16 dB EMI reduction depending on the system.

 

Q: What kinds of Spread Spectrum Clock (SSC) profiles are programmed and available?

A: Both the well known and frequently used “Lexmark™” profile (also known as “Hershey Kiss”) and “Triangular” profile (also known as “Linear”) can be programmed and are available.

 

Q: Could there be any legal problems with Lexmark when using patented “Lexmark™” profile?

A: Absolutely not. SpectraLinear has a license agreement with Lexmark and is fully authorized to use the “Lexmark™” spread spectrum profile. Contact SpectraLinear sales or marketing if additional information is required.

 

Q: Does SpectraLinear promote “Lexmark™” or “Triangular” profile?

A: SpectraLinear leaves it up to the customer as to which profile will be programmed for use in their systems. SpectraLinear can program either profile to meet the customer’s requirements.

 

Q: Does SpectraLinear plan to make I2C versions of the same SL15100/300 1-PLL SSCG products?

A: Yes we do. The introduction schedule for I2C version of these SSCG products is Q1-2009. Contact SpectraLinear sales or marketing if you need early samples of these products.

 

Q: When will 1.8V power supply versions of ZDB and NZDB (Fanout) buffers will be available?

A: Currently SpectraLinear has no plans to make these products available. However, all SpectraLinear ZDB and NZDB products are capable of operating with 1.8V power supply and this fact has been verified by SpectraLinear engineering.

SpectraLinear has not identified a sizeable market demand and has placed these products on hold. If a need exists, SpectraLinear could make these products available within 6 to 8 weeks. Please contact SpectraLinear sales or marketing if 1.8V power supply ZDB or NZDB products are needed.

 

Q: Do all SpectraLinear Clock Generators have on-chip programmable crystal load (CL) capacitors?

A: Yes, all SpectraLinear products have on-chip programmable crystal load (CL) capacitors. By using these on-chip capacitors, external crystal load capacitors are eliminated, saving additional cost and space. The typical range for programmable on-chip crystal load capacitor value is from 8.0 to 20.0pF with step programming resolution of 0.2pF-typ.

 

Q: What are the smallest packages offered by SpectraLinear EProClock® clock generators?

A: SL15102 and SL15302 1-PLL SSCG clock generators are offered in an 8-pin TDFN (3.0x3.0 mm body) package.

4-PLL SL38000 is offered in a 28-pin TSSOP package (9.8x4.5 mm body). We will be introducing 2/3/4 PLL versions of SL38000 in a 16-pin TSSOP (5.0x4.4 mm body) package.

In addition, 1-PLL clock generators are available in ultra-small, 6 pin TDFN (2.0x1.8 mm body) and 6-pin SC70 (2.0x1.3 mm body) packages for volume applications by making a simple mask change to SL15100/300 products.

Contact SpectraLinear sales and marketing for additional information.

 

Q: Can SpectraLinear products be used for military applications?

A: SpectraLinear products can be used for military applications as long as operational and test conditions do not exceed the product specifications given in product datasheets.

 

Q: Can SpectraLinear Programmable Clock Generators and EMI Reduction products operate beyond 200MHz?

A: SpectraLinear products can operate up to 300MHz if certain frequency, power supply, temperature and load conditions are met. This needs to be verified and confirmed by SpectraLinear engineering. Contact SpectraLinear sales and marketing if you have such a requirement.

 

Q: Are SpectraLinear products lead-free and RoHS compliant?

A: Yes, all SpectraLinear products, without exception, comply with all environmental legislations and regulatory requirements, including the Reduction of Hazardous Substances, RoHS Directive 2002/95/EC.

 

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SPECIFICATIONS


Q: What are the differences between CK505 version 0.85 and 1.0?

A: CK505 0.85 does not support:

  1. PCI-Express Gen2
  2. Full iAMT features
  3. PLL_CFG bit for hardware configuration

 

Q: Does SpectraLinear support industrial temperature?

A: SpectraLinear does support industrial temperature. Check the datasheet spec in the Product section. If the device does not support industrial temperature, contact to see if it is possible to support industrial temperature.

 

Q: Does the IDD in the datasheet means that is the total current the device will draw?

A: No, the IDD specified in the datasheet is for maximum loading with the highest operating frequency. IDD depends on loading, trace length and operating frequency.

 

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TECHNICAL


Q: What should I do with unused inputs and outputs?

A: Unused inputs should never be left floating since noise in the system may cause false triggering. Always tie unused inputs to a known logic high or logic low to avoid any unnecessary false triggering. Unused outputs on the other hand can be left floating.

 

Q: Why do the clocks outputs show very low frequencies in the KHz range vs. the correct frequency which should be in MHz?

A: Verify if the device has entered test mode. The device will enter test mode if FSC is considered a logic high, meaning the voltage level is greater than 2V.

 

Q: I have an EMI issue, can I spread the SATA clock beyond -0.5%?

A: No, spreading the SATA clock beyond -0.5% will cause hard drive issues.

 

Q: How do I minimize EMI?

A: There are three quick methods to reduce EMI.

  1. Use SL 3-bit slew rate control to slow down the edge rate
  2. Increase spread percentage
  3. Change the series termination resistor

 

Q: Can SpectraLinear’s clock generator take an external clock source rather than a crystal?

A: Yes, SpectraLinear’s clock generators will be able to support external clocks rather than a crystal if the external clock signal meets the input requirements on the datasheet.

 

Q: How long does it take for the PLL to lock?

A: The PLL will lock within a few milliseconds. This timing will include having the output stable.

 

Q: How much undershoot can my clock tolerate?

A: The maximum undershoot the clock can tolerate is -0.5V. Any lower voltage will cause the ESD diode to turn on, which may result in the unintentional toggling of output signals.

 

Q: How do I control the skew of the zero-delay buffers that have an external feedback loop?

A: Increasing the capacitor value in the feedback loop will create a leading skew. Reducing the capacitor in the feedback loop will create a lagging skew.

 

Q: Is it possible to interface with an SRC or CPU clock with LVDS or LVPECL inputs?

A: Yes, refer to application note 8 (AN8).

 

Q: What causes high jitter?

A: Poor decoupling to the power and ground planes and a slow edge rate contribute to high jitter.

 

Q: What is the output impedance of the device and is it important?

A: The output impedance of the device is the resistance between the NMOS to GND when the signal is driving the signal low and between the PMOS and VDD when the signal is driving the signal high. It is very important because it is part of the formula for having matched trace length. R(output_impedance) + R(termination) = Zo(trace).

 

Q: Is it mandatory to have separate power planes?

A: Yes, analog and digital power planes should never be mixed together. Mixing power planes will inject noise into the PLL resulting in higher jitter.

 

Q: Are PPM and jitter different?

A: Yes PPM and jitter are two completely different parameters. PPM (parts per million) defines the frequency accuracy of the clock. For example, a 200MHz clock with +/- 100PPM will have a frequency that can range from 24.9975MHz to 25.0025MHz. Jitter on the other hand is the instantaneous variation of frequency or phase.

 

Q: How do I match the trace impedance?

A: Trace impedance can be matched by using the following formula R(output impedance) + R(termination) = Zo(trace).

 

Q: What can I achieve with the 3-bit slew rate control?

A: The 3-bit slew rate control can reduce EMI, overshoot, undershoot, jitter, and impedance matching.

 

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SUPPORT


Q: What should I do if I want to order an EOL device?

A: Contact . We will check for availability or a replacement device.

 

Q: The datasheet I’m looking for is not on SpectraLinear’s website. Where can I find it?

A: If the datasheet is not available on the website, contact .

 

Q: I don’t see an IBIS model. Where can I get it?

A: If the IBIS model you are looking for is currently not available on our website, contact .

 

Q: Does SpectraLinear have an Asia support team?

A: Yes, for technical support in Asia, please contact .

 

Q: Is SpectraLinear part of Cypress Semiconductor?

A: No, SpectraLinear is an independent company. Our only association with Cypress Semiconductor was to acquire their PC Clocks product line in 2006.

 

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