AN10050 I2C/SPI Programmable Oscillators

SiTime Elite Platform™ I2C/SPI oscillators (SiT3521/2) are user programmable devices that enable the user to reprogram the clock and set the device output frequency to any supported value during operation using a digital interface (I2C or SPI). Two modes of operation are supported: 1) any-frequency mode with the capability to set the frequency to a new value within a wide frequency range (output is disabled for a short time) and 2), digitally controlled oscillator (DCO) mode that allows the output frequency to be continuously pulled within the specified pull range. Pull range can be changed in-system to one of 16 available pull range options. Additionally, I2C/SPI oscillators allow users to control the output enable (OE) state of the device and output driver settings (e.g. output swing). The SiT3521 (1 to 340 MHz) and the SiT3522 (340.000001 to 725 MHz) I2C/SPI oscillators support three signaling types: LVPECL, LVDS, and HCSL.


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