14. Register Map
14.1 Base vs. Factory Preprogrammed Devices
The Si5391/Si5391P devices can be ordered as “base” or “factory-preprogrammed” (also known as “custom OPN”) versions.
14.2 “Base” Devices (a.k.a. “Blank” Devices)
Example “base” orderable part numbers (OPNs) are of the form “Si5391A-E-GM” or “Si5391B-E-GM”.
Base devices are available for applications where volatile reads and writes are used to program and configure the device for a
particular application.
Base devices do not power up in a usable state (all output clocks are disabled).
Base devices are, however, configured by default to use a 48 MHz crystal on the XA/XB reference and a 1.8 V compatible I/O voltage
setting for the host I
2
C/SPI interface.
Additional programming of a base device is mandatory to achieve a usable configuration.
See the on-line lookup utility at:
https://www.skyworksinc.com/en/Application-Pages/Timing-Lookup-Customize
configuration plan and register settings for any base OPN.
14.3 “Factory Preprogrammed” (Custom OPN) Devices
Factory preprogammed devices use a “custom OPN”, such as Si5391A-E-xxxxx-GM, where xxxxx is a sequence of characters
assigned by Skyworks for each customer-specific configuration. These characters are referred to as the “OPN ID”. Customers must
initiate custom OPN creation using the ClockBuilder Pro software.
Many customers prefer to order devices which are factory preprogrammed for a particular application that includes specifying the
XA/XB reference frequency/type, the clock input frequencies, the clock output frequencies, as well as the other options, such as
automatic clock selection, loop BW, etc. The ClockBuilder software is required to select among all of these options and to produce a
project file which Skyworks uses to preprogram all devices with custom orderable part number (“custom OPN”).
Custom OPN devices contain all of the initialization information in their non-volatile memory (NVM) so that it powers up fully configured
and ready to go.
Because preprogrammed device applications are inherently quite different from one another, the default power up values of the
register settings can be determined using the custom OPN utility at:
https://www.skyworksinc.com/en/Application-Pages/Timing-Lookup-
Custom OPN devices include a device top mark which includes the unique OPN ID. Refer to the device data sheet's Ordering Guide
and Top Mark sections for more details.
Both “base” and “factory preprogrammed” devices can have their operating configurations changed at any time using volatile reads and
writes to the registers. Both types of devices can also have their current register configuration written to the NVM by executing an NVM
bank burn sequence (see Section .)
Si5391 Reference Manual • Register Map
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 0.5 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • January 11, 2022
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