SI5345_16 datasheet(11/60 Pages) SILABS

Nome de Peças	SI5345

Descrição Electrónicos	10-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier

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Fabricante Electrônico	SILABS [Silicon Laboratories]

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3.7.7 Synchronizing to Gapped Input Clocks

The DSPLL supports locking to an input clock that has missing periods. This is also referred to as a gapped clock. The purpose of

gapped clocking is to modulate the frequency of a periodic clock by selectively removing some of its cycles. Gapping a clock severely

increases its jitter so a phase-locked loop with high jitter tolerance and low loop bandwidth is required to produce a low-jitter periodic

clock. The resulting output will be a periodic non-gapped clock with an average frequency of the input with its missing cycles. For

example, an input clock of 100 MHz with one cycle removed every 10 cycles will result in a 90 MHz periodic non-gapped output clock.

This is shown in the following figure. For more information on gapped clocks, see “AN561: Introduction to Gapped Clocks and PLLs”.

DSPLL

100 ns

1

2

3

4

5

6

7

8

9

10

1

2

3

4

5

6

7

8

9

100 MHz clock

1 missing period every 10

90 MHz non-gapped clock

10 ns

11.11111... ns

Gapped Input Clock

Periodic Output Clock

Period Removed

Figure 3.5. Generating an Averaged Clock Output Frequency from a Gapped Clock Input

A valid gapped clock input must have a minimum frequency of 10 MHz with a maximum of two missing cycles out of every eight. Lock-

ing to a gapped clock will not trigger the LOS, OOF, and LOL fault monitors. Clock switching between gapped clocks may violate the

hitless switching specification in Table 5.8 Performance Characteristics on page 31 when the switch occurs during a gap in either

input clock.

3.8 Fault Monitoring

All four input clocks (IN0, IN1, IN2, IN3/FB_IN) are monitored for loss of signal (LOS) and out-of-frequency (OOF) as shown in the fig-

ure below. The reference at the XA/XB pins is also monitored for LOS since it provides a critical reference clock for the DSPLL. There is

also a Loss Of Lock (LOL) indicator which is asserted when the DSPLL loses synchronization.

DSPLL

LPF

PD

÷M

IN0

IN0b

Precision

Fast

OOF

LOS

÷P0

IN1

IN1b

Precision

Fast

OOF

LOS

÷P1

IN3/FB_IN

IN3/FB_INb

Precision

Fast

OOF

LOS

÷P3

IN2

IN2b

Precision

Fast

OOF

LOS

÷P2

LOL

XB

XA

OSC

LOS

Si5345/44/42

Figure 3.6. Si5345/44/42 Fault Monitors

Si5345/44/42 Rev D Data Sheet

Functional Description

silabs.com | Smart. Connected. Energy-friendly.

Rev. 1.0 | 10

Nº de peça semelhante - SI5345_16

Fabricante Electrônico	Nome de Peças	Folha de dados	Descrição Electrónicos
Silicon Laboratories	SI5345-44-42	1Mb / 62P	10-CHANNEL
Skyworks Solutions Inc.	SI5345-D-EVB	976Kb / 58P	10-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier Rev. 1.2
Silicon Laboratories	SI5345-EVB	2Mb / 19P	Powered from USB port or external power supply
Skyworks Solutions Inc.	SI5345A-D-GM1	976Kb / 58P	10-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier Rev. 1.2
Skyworks Solutions Inc.	SI5345B-D-GM1	976Kb / 58P	10-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier Rev. 1.2

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Descrição semelhante - SI5345_16

Fabricante Electrônico	Nome de Peças	Folha de dados	Descrição Electrónicos
Silicon Laboratories	SI5345	1Mb / 62P	10-CHANNEL, ANY-FREQUENCY, ANY-OUTPUT JITTER ATTENUATOR/CLOCK MULTIPLIER
Skyworks Solutions Inc.	SI5345	976Kb / 58P	10-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier Rev. 1.2
Skyworks Solutions Inc.	SI5395	1Mb / 61P	12-Channel, Any-Frequency, Any-Output Jitter Attenuator/ Clock Multiplier with Ultra-Low Jitter Rev. 1.2
Silicon Laboratories	SI5369	518Kb / 84P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR
Skyworks Solutions Inc.	SI5368	824Kb / 92P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR Rev. 1.0
Silicon Laboratories	SI5324C-C-GM	518Kb / 72P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/ JITTER ATTENUATOR
Silicon Laboratories	SI5327	1Mb / 60P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR
Skyworks Solutions Inc.	SI5319	1Mb / 50P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR Rev. 1.0
	SI5327	1Mb / 60P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR Rev. 1.0
	SI5326	550Kb / 71P	ANY-FREQUENCY PRECISION CLOCK MULTIPLIER/JITTER ATTENUATOR Rev. 1.0

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