Si53xx-RM

6.3. Pin Control Input Clock Control

This section describes the clock selection capabilities (manual input selection, automatic input selection, hitless switching, and revertive switching). When switching between two clocks, LOL may temporarily go high if the two clocks differ in frequency by more than 100 ppm.

6.3.1. Manual Clock Selection

Manual control of input clock selection is chosen via the CS[1:0] pins according to Table 22 and Table 23.

Table 22. Manual Input Clock Selection (Si5316, Si5322, Si5323), AUTOSEL = L

CS (Si5316)

Si5316

Si5322

Si5323

CS_CA (Si5322, Si5323)

 

 

 

 

 

 

 

0

 

CKIN1

 

 

 

 

 

1

 

CKIN2

 

 

 

 

 

The manual input clock selection settings for the Si5365 and the Si5366 are shown in Table 23. The Si5366 has two modes of operation (See Section “6.5. Frame Synchronization (Si5366)”). With CK_CONF = 0, any of the four input clocks may be selected manually; however, when CK_CONF = 1 the inputs are paired, CKIN1 is paired with CKIN3 and likewise for CKIN2 and CKIN4. Therefore, only two settings are available to select one of the two pairs.

Table 23. Manual Input Clock Selection (Si5365, Si5366), AUTOSEL = L

[CS1_CA4, CS0_CA3]_Pins

Si5365

 

Si5366

 

 

 

 

 

 

 

CK_CONF = 0

 

CK_CONF = 1

 

 

(5 Output Clocks)

 

(FS_OUT Configuration)

 

 

 

 

 

00

CKIN1

CKIN1

 

CKIN1/CKIN3

 

 

 

 

 

01

CKIN2

CKIN2

 

CKIN2/CKIN4

 

 

 

 

 

10

CKIN3

CKIN3

 

Reserved

 

 

 

 

 

11

CKIN4

CKIN4

 

Reserved

 

 

 

 

 

Notes:

1.To avoid clock switching based on intermediate states during a CS state change, the CS input pins are internally deglitched.

2.If the selected clock enters an alarm condition, the PLL enters digital hold mode.

Rev. 0.5

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Silicon Laboratories SI5327 Pin Control Input Clock Control, Manual Input Clock Selection Si5365, Si5366, Autosel = L