Si5334, Si5335, Si5338 Frequently Asked Questions

Table 1. Si5334, Si5335, and Si5338 Product Links

Table 2. Si5334, Si5335, and Si5338 Relevant Application Notes

Frequently Asked Questions

1. What is the main difference between the Si5334, Si5335, and Si5338?

   The Si5334 is a pin control only part, with pre-defined pinouts depending on the selected part number (Si5334A, Si5334B, etc). Please see page 23 of the Si5334 Datasheet for more details on the different available part numbers.

   The Si5335 is also a pin control only part, however it has some additional functionality compared to the Si5334. The Si5335 can select either 1.6MHz or 475kHz as the PLL loop bandwidth. See Page 35 in the Si5335 Datasheet for an in-depth description of the two options. Also, AN614 has additional application specific details on how to select the proper bandwidth.

   The Si5335 offers up to three pin controlled custom frequency profiles. ClockBuilder Pro can be used to setup each profile. The finished part will use up to two frequency select pins to select between the different configurations.

   The Si5338 is a fully I2C programmable clock generator. See the Si5338 Reference Manual for detailed programming instructions.

2. Where is the RoHS, REACH, or other material related compliance information for the Si5334, Si5335, and Si5338?

   Please refer to our Corporate, Product and Environmental Data Search (by Part Number) webpage for full RoHS, REACH and other material composition information.

3. Where is the FIT information for the Si5334, Si5335, and Si5338?

   FIT information for all Silicon Labs products can be found on the Corporate Commitment to Quality Page. Look for the Quality and Reliability Monitor Report near the bottom. Look for the Si533X part number. The Si5334, Si5335, and Si5338 all use 0.13um technology.

4. How can I get a Si5334, Si5335, and Si5338 with a custom startup frequency?

   You can use ClockBuilder Pro to create a custom part number for all three products. After you create your custom plan, you will have the option to "create a custom part number" under the "Silicon Labs Cloud Services" tab. This will officially create the part number in our system. After this step, your custom part number will be orderable from your local distributor. Please contact your local Silicon Labs sales representative if you have questions.

   In addition to the CBPro customization, the Si5334 has pre-defined "standard frequency plan" part numbers that can be found near the end of the datasheet. These will all be orderable from your local distributor.

5. What is the default I2C Address of the Si5338 when the part does not have an I2C_LSB pin or a custom address?

   The default address of the Si5338 will always be 0x70h. The I2C_LSB pin is only an option for the Si5338K/L/M part numbers. All other Si5338 devices will either have 0x70h as their default address, or they can have a custom I2C address defined by a custom configuration from ClockBuilder Pro. When you create a custom part number in CBPro for the Si5338, you will have the option to define a new I2C address if you want to.

6. What finish is used on the contacts of the Si5334, Si5335, or Si5338?

   The 24 Lead QFN, 4x4mm contacts are NiPdAu, with:

   • Ni: 10u" min
   • Pd: 0.1u" min
   • Ag-Au alloy: 0.2u" min (Silver content is very low)

   If you require more detail on lead finish, please work through your Silicon Labs sales rep to submit an RFI (Request For Information) with the details of the additional information you need.

7. How can I burn the NVM on a blank Si5338 part?

   You can burn the NVM (Non-Volatile Memory) of a blank loose Si5338 using the Si5338-56-prog-evb-evaluation-kit.

   • Once a blank Si5338 has been programmed, it can then be removed from the Field Programmer and mounted on a PCB for prototyping purposes.
   • NOTE: Pre-programmed Si5338 devices cannot be re-programmed using the Field Programmer. It is only designed to be used with loose blank parts for non-production sample purposes only.

   After a profile has been vetted, and it is ready for production, use CBPro to create a new custom part number for that profile. Once a part number is created, you will be able to contact your local distributor to place an order for that new part number containing your new custom profile.

8. Will the ClockBuilder Pro Field Programmer (CBPROG-DONGLE) work with the Si5334, Si5335, or Si5338?

   The CBProg-Dongle does support volatile I2C communication with a Si5338.

   • Connect the GND, SCLK, and SDA_SDIO pins from the Dongle to the GND, SCL, and SDA pins on the Si5338.
   • ClockBuilder Pro can then be used to modify individual volatile registers or write full project files to the Si5338.
   • NOTE: The dongle cannot be used to burn the NVM of an in system or loose Si5334, Si5335, or Si5338. It only supports NVM programming of the Si538x, Si534x, and Si5332 products. Please use the Si5338/Si5356 field programmer to burn the NVM of loose Si5338 samples.

9. Where can I find software for the Si5338 Field Programmer?

   ClockBuilder Pro now supports burning loose parts with the Si5338-56 Field Programmer. If needed, here is a link to the older Clock Builder Desktop software.

   • Clicking the hyperlink will automatically download the software to your computer.
   • Open the "Si5338-56 Field Programmer - Clock Builder Desktop 6.5" executable to interface with the Field Programmer board.

10. How can I use a CBPro project file with the Field Programmer?

    In the Si5338 CBPro Project file, go to "Export"/"Register File", and select the "FP NVM Export" option to create and save off your NVM file.

    This export will contain the registers that need to be written to the Si5338 to achieve your design/configuration. A command line version of this tool is available. Type CBProProjectRegistersExport --help from a command prompt to learn more.

    Now, with the Si5338/Si5356 Field Programmer plugged in, open the Field Programmer GUI through the CBPro Design dashboard. Open the recently saved off NVM file in the GUI, click "Write NVM" and your part will be burned to match your CBPro Project file.

11. Does the Si5338 support in-circuit NVM programming?

    • No, the Si5338 NVM can not be in-circuit programmed. It only supports volatile I2C programming, which will be reset to the factory defaults when power is cycled.
    • The Field Programmer is only designed to be used with loose blank Si5338 parts. It is not designed to burn a pre-soldered Si5338.
    • One option for in-system I2C programming, is to use a flashed microcontroller to automatically configure the Si5338 on power up. See AN428 for a full description of this solution.

12. Can I import a Si5338 ClockBuilder Desktop NVM file into ClockBuilder Pro?

    • Yes, just click the "Convert Existing Project/NVM File" link in the main Clock Builder Pro Wizard page.
    • At the top of the next window, select the "Si5338 CBDesktop NVM File" and click next.
    • Finally, find and import the ClockBuilder Desktop NVM file in question.
    • The full original ClockBuilder Desktop configuration will now be available in the ClockBuilder Pro design dashboard. You can now edit the configuration and create a new custom part number.

13. How do I control the Si5338-EVB?

    • ClockBuilder Pro is the recommended software to use along side the Si5338-EVB.
    • When an EVB is plugged into a computer via the USB cable, CBPro will recognize the EVB and allow you to write any existing Si5338 project file to the installed Si5338 device.
    • Additional information on how to use the Si5338-EVB can be found in the Si5330/34/35/38 Evaluation Board User's Guide

14. What if I want a feature in my custom Si5334, Si5335, or Si5338 that is not configurable in ClockBuilder Pro?

    • If ClockBuilder Pro is currently missing a configuration option that you would like included in your custom part, just create a new support ticket and we will be able to add your new settings for you.
    • When contacting support, remember to include your existing ClockBuilder Pro Project and a description of the functionality you would like added. We can then send a new updated ClockBuilder Pro Project file back to you. Just submit the new modified configuration and your new part number will include your desired functionality.

15. What is the minimum slew rate for the power supply ramp on Vdd?

    0.5V/ms between 1.45V and 1.62V

16. What power supply sequence/delay is required for Vdd and VDDOx?

    None, unless a pre-programmed phase offset is expected between outputs. In that case, there should be no more than 500us from the time VDD crosses 1.45V until the output VDDOx crosses 1.2V.

17. What should unused VDDOx pins be connected to?

    Tie all unused VDDOx pins to VDD.

18. When an LOS or LOL occurs, will the outputs be squelched?

    • No, the output clocks will continue to toggle even with a LOS or LOL interrupt. Without a reference, the frequencies can drift up to 5% in clock generator mode.
    • One way around this is to tie the interrupt pin to an OEB pin. When the pin goes high due to an interrupt, the OEB pin will also be pulled high disabling the outputs. Since the interrupt pin is open drain, it is still important to include the suggested 1-4kohm pullup.

19. What do I need to communicate to a Si5338 via I2C?

    • You can use any I2C bus master that allows both read and write cycles over the I2C bus (e.g. MCU or FPGA). The basic Si5338 I2C configuration process requires reading registers (sometimes referred to as RAM in data sheet), modifying the data programmatically, and then writing a new value. As long as the I2C bus master adapter can do these operations, you should be able to configure the device. I2C configuration can be done to any Si5338 device variant with I2C bus support, whether it is a custom part or blank part.
    • Creating a configuration to load into registers (RAM) is different than creating a NVM configuration. Please refer to the Si5338 data sheet, sections 3.5.2 and 3.5.3. For hardware design related data specific of our I2C interface, please refer to Si5338 data sheet Table 15 "I2C specifications (SCL, SDA)".
    • We provide the details of the I2C configuration process and sample C code in application note AN428. We don't provide any software drivers or HDL code (for FPGAs).

20. How do I configure a Si5338 via I2C?

    There are 3 main documents to use as a reference in understanding the I2C configuration process. If you are new to the I2C configuration process, please review these closely. You must follow the complete process described in the documents listed below in order for the device to work properly.

    1. Si5338 data sheet: Read sections 3.5.1, 3.5.2, and 3.5.3 as well as Figure 9. (Section 3.5.4 describes the Field Programmer for NVM programming of prototype parts.) These sections of the data sheet outlines the process that must be followed when loading a new configuration. Note: The entire register map must be written when making configuration changes. Do not change individual registers based on looking at file differences when changing/modifying configurations, this can lead to improper configuration of the device.
    2. AN428: Jump Start for In-System, Flash-Based Programming: AN428 is an application note that describes in-system configuration via I2C using a microcontroller (MCU). It contains C source code for our C8051F3xx MCU family. The code specific to performing the Si5338 configuration starts on page 24 of this document and it implements the flow chart shown in Figure 9 of the Si5338 data sheet. (This code can be used as a guide to implement your own code.) The data array required for this code, which contains the register settings plus the write-allowed mask, can be automatically generated using ClockBuilder Pro. (See Si5338 data sheet, section 3.5.2, item 1.g.). Importantly, please closely adhere to, and do not deviate from, not only the event sequences as indicated in the Figure 9 flowchart, but the required time delays as well. You must use the "write-allowed" masks when writing to registers because some registers contain bits that should not be modified and can't be determined beforehand. Doing the required read/modify/write register operation is essential.
    3. Si5338 Reference Manual: This is a good reference document to understand how the device works with detailed register descriptions. It contains a good "from scratch" description of how to configure the device without using ClockBuilder Pro, but...we strongly recommend leveraging ClockBuilder Pro and the C code in AN428 if possible.

21. What is the Input-Output delay of the Si5335 in ZDB and NZDB modes?

    TPROP refers to the IO delay in Non-Zero-Delay Buffer mode (also known as PLL bypass). This spec does not apply to Zero Delay Buffer Mode since the PLL is in use. TPROP_ZDB = Expected propagation delay in Zero Delay Buffer Mode = +/-200 pS. The table (same as Table 3 in page 6 of Si5335 datasheet) below provides a TPROP value.

    Table 3. Performance Characteristics

    Parameter	Symbol	Test Condition	Min	Typ	Max	Unit
    PLL Acquisition Time	TACQ	1.6 MHz loop bandwidth		25		ms
    PLL Tracking Range	fTRACK	475 kHz or 1.6 MHz loop bandwidth	5000	20000		ppm
    PLL Loop Bandwidth	fBW1	High bandwidth option		1.6		MHz
    	fBW2	Low bandwidth option		475		kHz
    MultiSynth Frequency Synthesis Resolution	fRES	Output frequency ≤ Fvco/8	0	0	1	ppb
    CLKIN Loss of Signal Detect Time	tLOS			2.6	5	µs
    CLKIN Loss of Signal Release Time	tLOSRLS		0.01	0.2	1	µs
    POR to Output Clock Valid	tRDY				2	ms
    Input-to-Output Propagation Delay	tPROP	Buffer Mode (PLL Bypass)		2.5	4	ns
    Reset Minimum Pulse Width	tRESET			200		ns
    Output-Output Skew¹	tDSKEW	FOUT≥ 5 MHz		100		ps
    Spread Spectrum PP Frequency Deviation²	tSSDEV	FOUT = 100 MHz	–	–0.45	–0.5	%
    Spread Spectrum Modulation Rate³	tSSDEV	FOUT = 100 MHz	30	31.5	33	kHz

    Notes:
    1. Outputs at integer-related frequencies and using the same driver format.
    2. Default value is 0.5% down spread.
    3. Default value is 31.5 kHz for PCI compliance.

22. Can the Si5335/Si5338 clock generators support spread spectrum inputs?

    • The Si5335/Si5338 are generally used as "spread-aware" clock generators i.e. PLLs that do not attenuate spread spectrum clocking at the input clocks. These products can be used as spread-aware clock generators as long as the input follows the following conditions:
    • The input spread percentage should be within the tracking range of Si5335/Si5338 which is 20,000 ppm. This translates to a maximum specification of +/-2%.
    • The modulation rate cannot exceed 1.5MHz.
    • If those two conditions are met, the Si5335 and Si5338 can be used as spread aware clock generators.