Si5351A Synthesizer Kit

Description

S15351A Frequency Synthesizer Oscillator Kit.

This is a kit and you will be receiving a plastic bag with components. The photos are representative examples of the completed kit. The Si5351A is a relatively recent clock-generator chip manufactured by </span><a href=”http://www.silabs.com/” target=”_blank”>SiLabs</a><span>. It can produce three simultaneous independent 50-ohm impedance, squarewave outputs between 8kHz and 200MHz [See note]. Configuration of the chip is via a microcontroller with I2C (two-wire) interface. This kit (a.k.a. “breakout board”) contains a pre-soldered Si5351A chip, 3.3V regulator, and I2C level converters.

This Si5351A synthesiser module kit (or “breakout board”) runs from a 5V or 3.3V supply. The tiny 0.5mm pin-spaced Si5351A chip is pre-soldered to the PCB at the factory. The PCB size is 1.3 x 1 inches (33 x 25mm). The remaining components are all through-hole components so construction is easy. The circuit contains a 3.3V regulator and I2C level converters, for use with 5V microcontroller systems. The kit may also be built without the level converters or regulator, for use in 3.3V systems. The kit has a 2 x 10-pin 0.1-inch header for all connections. Additionally pads are provided on the PCB for soldering SMA connectors if you wish. The kit uses a 27MHz crystal as the reference oscillator.

The synthesizer may be used in a variety of projects. The pinout has been designed to be somewhat similar to the popular AD9850 DDS module and may be substituted in certain cases (with appropriate software changes in the controller). This Si5351A module is also designed to be compatible with the <a href=”https://www.qrp-labs.com/ultimate3″ target=”_blank”>Ultimate3/3S QRSS/WSPR kits</a>. It can be plugged into the <a href=”https://www.qrp-labs.com/ultimate3″ target=”_blank”>U3 kit</a> with certain minimal hardware modifications to the U3. It is directly compatible with the <a href=”https://www.qrp-labs.com/ultimate3/u3s.html” target=”_blank”>Ultimate3S kit</a> without modifications. It requires Ultimate3 firmware v3.07 or above, to communicate with the Si5351A via I2C. Note that for use in the original U3, not U3S, (PCB revisions 1 to 4), pin 12 of the header needs to be removed before installation.</p><p>Starting from PCB Rev 4, the PCB has pads that will support use of a 7 x 5-mm or 5 x 3.2-mm SMD 27MHz TCXO (not supplied) instead of the supplied 27MHz crystal. Please refer to Rev 4 assembly manual, see below.

NOTE: QRP Labs tested the actual frequency range of the Si5351A outputs. The minimum frequency configuration with 27MHz crystal produces 3.515kHz output. The maximum frequency appears to be an internal limitation (not limited by the configuration) and was approximately 292MHz. Of course, outside the specified range of the datasheet (8kHz – 200MHz), there are no guarantees…