Si5351 clock generator family (Si5351A / Si5351B / Si5351C) Key benefits Flexible multi-output clocking: generate up to 8 independently programmable clock outputs to replace multiple crystals, crystal oscillators, VCXOs, PLLs or fanout buffers in the same design. Wide frequency range: each output can produce non-integer frequencies from 8 kHz to 160 MHz under I2C control, enabling precise clocks for many digital, RF and timing use cases. Tunable and synchronized options: choose a free-running internal reference (Si5351A), an internal VCXO for pulled-crystal-style tuning (Si5351B), or synchronization to an external reference clock (Si5351C with CLKIN). High-resolution fractional division: PLL + VCXO + MultiSynth architecture delivers fine frequency resolution and deterministic output generation for cost-sensitive designs. Simple control and integration: I2C interface makes it easy to program and change frequencies from microcontrollers or system controllers. Main features Up to 8 output clocks, independently programmable. Frequency range: 8 kHz to 160 MHz (non-integer frequencies supported). I2C control for run-time programming and reconfiguration. MultiSynth + PLL architecture with high-resolution fractional dividers. Si5351C: synchronizes to an external reference clock (CLKIN). Si5351A: internal oscillator for free-running clock generation, suitable to replace crystals and quartz oscillators. Si5351B: internal VCXO for replacing both free-running clocks and pulled-crystal-style synchronous clocks, providing reliable operation over a wide tuning range. Targeted for cost-sensitive applications requiring multiple precise clocks. Compatibility and usage considerations Interfaces with standard I2C host controllers for configuration and dynamic frequency changes. Designed to replace discrete crystals or multiple oscillator ICs, reducing BOM complexity and board real estate when multiple clock sources are required. Works as a direct clock source for microcontrollers, FPGAs, PLLs, RF transceivers and fanout buffer inputs. Typical use scenarios 1) Single-board replacements for multiple crystal oscillators: replace several fixed-frequency crystals on a PCB with one Si5351 device to centralize clock generation, simplify inventory, and enable software-configurable frequencies for different product variants. 2) SDR, RF or test equipment clocking: use Si5351 outputs to supply precise, programmable reference clocks (8 kHz–160 MHz) for receivers, transmitters or test setups; use Si5351C when synchronization to an external reference is required. 3) Programmable system timing for embedded designs: supply multiple device clocks (MCU, FPGA, codec) with different frequencies from a single I2C-configurable source; use Si5351B when an internally tuned VCXO-like behavior is needed for robust operation across a wide tuning range. Performance and reliability notes Provides high-resolution fractional frequency generation via PLL/VCXO + MultiSynth to meet precise timing needs. Supports deterministic multi-output clocking for synchronous systems. The product family addresses cost-sensitive designs while offering the flexibility to replace and extend traditional crystal/oscillator solutions. Si5351 variants maintain consistent functionality across models: up to 8 outputs, I2C control, and frequency range 8 kHz–160 MHz; Si5351C adds external CLKIN synchronization, Si5351A includes an internal free-running oscillator, and Si5351B includes an internal VCXO for pulled-crystal-style tuning and wide-range reliable operation. Model summary Si5351: configurable I2C clock generator for crystals, crystal oscillators, VCXOs