Skyworks Si5338 - Feedback Clock Select

Si5338-RM
14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
Rev. 1.4 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • 2021
4.2. Feedback Clock Select
The feedback pins (IN4, IN5/IN6) can be used in external feedback mode (for zero delay applications), or as
alternate reference inputs. The IN5/IN6 pins provide a differential input and IN4 accepts a single-ended input. Only
the Si5338N/P/Q devices allow IN4 to be used as a single-ended clock input. The registers responsible for
selecting/configuring external feedback clock inputs are shown in Figure 8.
Figure 8. Feedback Input Configuration Registers
When the Si5338 is used in the zero delay mode, set the PFD_EXTFB bit = 1 (register 48[7] = 1). When the Si5338
is not in the zero delay mode, set the PFD_EXTFB bit = 0 (register 48[7] = 0).
28[7:0]
P2DIV
_IN[0]
01
01234567
30[7:0]
01234567
P2DIV_IN[2:1]
P2DIV_IN[0]
00
01
10
IN5/IN6 (differential)
Feedback Clock P2DIV_IN[2:1]
0
1
0
IN4 (single-ended)
No clock input to P2