Using multiple SI5351A's

Addressing SI5351A on I2C bus depends on the address, typically 0x60. To use multiple chips they have to have unique I2C addresses. There are some pre-programmed versions such as SI5351A-B04486-GT. How do you interpret the B04486-GT extension? Does it have a different address?

Stan Pozerski

Welcome to the forum.

Page 34 of the data sheet shows the part numbering breakdown.

I2C addressing is covered on page 18. It says that there are only two address choices, the default of 0x60 and if you pull the A0 pin high you get 0x61. It also says that only the 16 and 20 pin packages have the A0 pin available for use.

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I understand the A0 issue on the B and C versions. But the SI5351A-B04486-GT is a preprogrammed device so that address may be different. In fact, I have seen references that say this particular part has an address of 0X62. How can I get the specs for this particular device. The websites all refer to only the generic documentation. The device probably also has pre-determined output frequencies on power up which can be overridden.

In most instances where “custom” factory configurations are assigned a unique, non-coding part number (e.g. the P/N doesn’t directly define the config) the configuration isn’t publicly listed; at the same time, such parts usually aren’t regular-stock items sold to the general public, as this appears to be.

I’ll make inquiries to find out if if this information can be made available. In the meantime, the generic documentation doesn’t seem to imply that the I2C address itself is a configurable attribute, but perhaps these other references you mention have information to the contrary.

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The following summary is what I received in response:

SI5351A-B02075-GT 27Mhz 24.576Mhz NA NA 0x6F
SI5351A-B04486-GT 25Mhz 24Mhz 24Mhz 45.1584Mhz 0x62