Si5351A I2C Clock Signal Generator Module — DC 3V to 5V (CJMCU-5351)
The Si5351A is a programmable clock generator that produces up to three independent square-wave outputs simultaneously, each configurable from 8kHz to 160MHz over I2C. A single 25MHz crystal reference generates all outputs through fractional PLL synthesis, and frequency resolution reaches below 1 Hz at lower frequencies. This makes it the standard choice for software-defined radio (SDR) VFO generators, function generator modules, and multi-clock test setups where a fixed crystal oscillator is too inflexible.
- 3 independent clock outputs — CLK0, CLK1, CLK2
- 8kHz to 160MHz output range — per channel
- Sub-Hz frequency resolution — fractional PLL synthesis
- I2C control — address 0x60, programmed with Si5351 library
- 3V–5V supply — direct Arduino and ESP32 connection
| Specification | Value |
|---|---|
| IC | Si5351A (Silicon Labs) |
| Output channels | 3 (CLK0, CLK1, CLK2) |
| Frequency range | 8kHz – 160MHz |
| Interface | I2C (address 0x60) |
| Reference crystal | 25MHz (onboard) |
| Supply voltage | 3V – 5V |
How do you control the Si5351A from Arduino?
The Etherkit Si5351 Arduino library (available in Library Manager) handles all register programming. Calling si5351.set_freq(14074000ULL * 100ULL, SI5351_CLK0) sets CLK0 to 14.074MHz (the 20m FT8 frequency) in one line. Frequency is specified in hundredths of Hz for maximum resolution.
Best for
Software-defined radio VFO generators, QRP amateur radio transceivers, function generator builds, clock distribution for multi-ADC systems, audio test oscillators, and anywhere three programmable clock sources are needed without multiple discrete oscillators.
Why Kunkune
Shipped from UK stock. 60-day returns, no minimum order. Fast Royal Mail delivery.
Buying in bulk? For orders of 10+ units, contact us for trade pricing.
