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Full machine-readable index: https://core-electronics.com.au/llms.txt # Adafruit Si5351A Clock Generator with STEMMA QT - 8KHz to 160MHz **Type:** Product page · **SKU:** ADA5640 · **Brand:** [Adafruit](https://core-electronics.com.au/brands/adafruit-australia) **Page:** https://core-electronics.com.au/adafruit-si5351a-clock-generator-with-stemma-qt-8khz-to-160mhz.html ([markdown](https://core-electronics.com.au/adafruit-si5351a-clock-generator-with-stemma-qt-8khz-to-160mhz.html.md)) Never hunt around for another crystal again, with the Si5351A clock generator breakout from Adafruit! This chip has a precision 25MHz crystal reference... ## Pricing - **Price:** $13.90 (inc GST) — $12.64 AUD, exc GST - **Quantity discounts:** 10+ $12.25 (exc GST) · 50+ $12.00 (exc GST) ## Availability & dispatch - In stock, ships same business day if ordered before 2PM (Australia/Sydney). - We can dispatch 1 today, and up to 23 more in 8–12 days. ## How to buy - **Build a cart:** compose `https://core-electronics.com.au/cart/link?items=ADA5640:1` (comma-separated SKU:qty pairs) and share the link. Opening it shows a confirmation page with live pricing and stock before anything is added to the cart. - **Verify the cart first:** fetch `https://core-electronics.com.au/cart/link/ADA5640:1.md` for live line prices (inc & exc GST, quantity discounts applied), stock and dispatch estimates, and totals. Append `/to/{AU-postcode}` (or `/to/{country-code}:{postcode}`) before `.md` for delivery options and prices to that destination. Unknown, retired, or out-of-stock SKUs are flagged. (Query form `cart/link.md?items=...` also works but some robots parsers refuse query strings here.) - **Checkout** is completed on-site and includes a captcha at the payment step. Share the cart link; checkout takes it from there. - **Search the catalogue:** `https://core-electronics.com.au/search/{query}.md` (URL-encode the query; pages 2-3 at `search/{query}/{page}.md`; `search.md?q=` also works) - **Payment methods, purchase orders, policies and contact details:** https://core-electronics.com.au/llms.txt ## Description Never hunt around for another crystal again, with the Si5351A clock generator breakout from Adafruit! This chip has a precision 25MHz crystal reference and internal PLL and dividers so it can generate just about any frequency, from <8KHz up to 150+ MHz. The Si5351A clock generator is an I2C controller clock generator. It uses the onboard precision clock to drive multiple PLL's and clock dividers using I2C instructions. By setting up the PLL and dividers you can create precise and arbitrary frequencies. There are three independent outputs, and each one can have a different frequency. Outputs are 3Vpp, either through a breadboard-friendly header or, for RF work, an [optional edge-launch SMA connector](https://core-electronics.com.au/edge-launch-sma-connector-for-1-6mm-0-062-thick-pcbs.html) for output #1. ([If you need SMA-connector outputs for all three ports, check out the non-QT breakout here](https://core-electronics.com.au/adafruit-si5351a-clock-generator-breakout-board-8khz-to-160mhz.html)) To get you going fast, Adafruit spun up a custom-made PCB in the[ **STEMMA QT** form factor](https://core-electronics.com.au/search?q=stemma%20qt%20sensor), making it easy to interface with. The [STEMMA QT connectors](https://learn.adafruit.com/introducing-adafruit-stemma-qt/what-is-stemma-qt) on either side are compatible with the [SparkFun Qwiic](https://core-electronics.com.au/catalogsearch/result/?q=qwiic) I2C connectors. This allows you to make solderless connections between your development board and the Si5351 or to chain it with a wide range of other sensors and accessories using a [**compatible cable**](https://core-electronics.com.au/search?q=stemma%20qt%20cable). Onboard 3.3V LDO and level shifters means its ready for use with 3V or 5V power and logic! [Best of all, Adafruit even have a great tutorial and library to get you started! Adafruit's code is designed for use with the Arduino-compatible microcontrollers and CircuitPython/Python](https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout) using I2C support. ## Technical Details - [Datasheets, PCB CAD files, and Fritzing objects available in tutorial](https://learn.adafruit.com/adafruit-si5351-clock-generator-breakout/downloads) **Si5351 specifications:** - Generates up to 3 non-integer-related frequencies from 8 kHz to 160 MHzI2C user definable configuration ? Exact frequency synthesis at each output (0 ppm error) - Highly linear VCXO - Low output period jitter: 100 ps pp - Configurable spread spectrum selectable at each output - Operates from a low-cost, fixed frequency crystal: 25 MHz on board - Supports static phase offset - Programmable rise/fall time control - Glitchless frequency changes - Excellent PSRR eliminates external power supply filtering - Very low power consumption - Adjustable output-output dela - PCIE Gen 1 compliant - Supports HCSL compatible swing Product Dimensions: 25.3mm x 17.7mm x 4.7mm / 1.0" x 0.7" x 0.2" Product Weight: 1.7g / 0.1oz ![RoHS 2 2011 65 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2011_65_EU_7356c5574c.svg)![RoHS 2 2015 863 EU Compliant](https://core-electronics.com.au/attachments/localcontent/RoHS2_2015_863_EU_86773f57f9.svg) ## Images - [Product image 1](https://core-electronics.com.au/media/catalog/product/A/D/ADA5640-1.jpg)