Silicon Laboratories SI5351A/B/C Configuring the Si5351, Writing a Custom Configuration to RAM

Models: SI5351A/B/C

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Si5351A/B/C

5. Configuring the Si5351

The Si5351 is a highly flexible clock generator which is entirely configurable through its I2C interface. The device’s default configuration is stored in non-volatile memory (NVM) as shown in Figure 11. The NVM is a one time programmable memory (OTP) which can store a custom user configuration at power-up. This is a useful feature for applications that need a clock present at power-up (e.g., for providing a clock to a processor).

Power-Up

NVM

(OTP)

Default Config

RAM

I2C

Figure 11. Si5351 Memory Configuration

During a power cycle the contents of the NVM are copied into random access memory (RAM), which sets the device configuration that will be used during normal operation. Any changes to the device configuration after power-up are made by reading and writing to registers in the RAM space through the I2C interface. A detailed register map is shown in Section "8. Register Descriptions" on page 25.

5.1. Writing a Custom Configuration to RAM

To simplify device configuration, Silicon Labs has released the ClockBuilder Desktop. The software serves two purposes: to configure the Si5351 with optimal configuration based on the desired frequencies and to control the EVB when connected to a host PC.

The optimal configuration can be saved from the software in text files that can be used in any system, which configures the device over I2C. ClockBuilder Desktop can be downloaded from www.silabs.com/ClockBuilder and runs on Windows XP, Windows Vista, and Windows 7.

Once the configuration file has been saved, the device can be programmed via I2C by following the steps shown in Figure 12.

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Silicon Laboratories SI5351A/B/C specifications Configuring the Si5351, Writing a Custom Configuration to RAM, Power-Up

SI5351A/B/C specifications

Silicon Laboratories SI5351A/B/C is a versatile, low-power clock generator and frequency synthesizer that has gained widespread popularity in various applications, including telecommunications, consumer electronics, and industrial control systems. These devices are primarily designed to provide precise clock frequency generation with low phase noise and jitter, making them ideal for high-performance applications.

One of the standout features of the SI5351 is its ability to generate multiple output frequencies simultaneously. Capable of producing up to three independent programmable outputs, the SI5351A/B/C can generate frequencies ranging from 8 kHz to 160 MHz. With its integrated phase-locked loop (PLL) technology, it achieves excellent frequency stability and accuracy, simplifying the design of frequency-dependent systems.

The device operates under a supply voltage range of 1.8V to 3.6V, allowing it to be used in battery-powered applications without excessive power consumption. The SI5351’s low current draw, typically as low as 25 mA, is especially beneficial in portable devices, extending battery life and enhancing overall efficiency. Furthermore, it features a programmable output driver, which can be set to various drive strengths, ensuring compatibility with a wide array of load requirements.

Configuration and control of the SI5351 are user-friendly, implemented via an I2C interface. This allows for straightforward integration into microcontroller-based designs. Moreover, the device includes an on-chip memory that stores settings, which streamlines the reconfiguration process when power cycling, minimizing setup time for developers.

Another significant advantage of the SI5351A/B/C is its output jitter performance, which is typically below 1 ps, resulting in clean output signals essential for high-speed data communications and precise timing applications. The SI5351’s integration of multiple synthesizer stages contributes to its impressive phase noise characteristics, making it suitable for demanding RF applications.

Additionally, the SI5351 devices offer programmable frequency stepping, allowing users to define custom frequency increments, which is particularly useful in applications requiring precise tuning or modulation. This flexibility, combined with its compact size and simple interface, makes the SI5351A/B/C an ideal choice for engineers seeking a reliable, cost-effective solution for generating clock signals in a myriad of electronic systems.

In summary, Silicon Laboratories SI5351A/B/C provides a robust, low-power solution for high-precision clock generation, characterized by its programmable outputs, low jitter, easy configurability, and broad frequency range, making it an excellent choice for both commercial and industrial applications across various sectors.