SI5332C-C-GM3R View Datasheet(PDF) - Silicon Laboratories

Part Name

Description

MFG CO.

SI5332C-C-GM3R

6/8/12-Output Any-Frequency Clock Generator

Silicon Laboratories 

Si5332 Data Sheet

Functional Description

3.5.9 Output Driver State When Disabled

The disabled state of an output driver is configurable as: disable low, disable high, or disable high-impedance.

3.5.10 Synchronous Output Disable Feature

Output clocks are always enabled and disabled synchronously. The output will wait until a clock period has completed before the driver

is disabled. This prevents unwanted runt pulses from occurring when disabling an output.

3.6 Spread Spectrum

To help reduce electromagnetic interference (EMI), the Si5332 supports spread spectrum modulation. The output clock frequencies can

be modulated to spread energy across a broader range of frequencies, lowering system EMI. The Si5332 implements spread spectrum

using its patented MultiSynth technology to achieve previously unattainable precision in both modulation rate and spreading magnitude.

Spread spectrum can be enabled through I2C, or by configuring one of the universal hardware input pins using ClockBuilder Pro.

The Si5332 features both center and down spread spectrum modulation capability, from 0.1% to 2.5%. Each MultiSynth is capable of

generating an independent spread spectrum clock. The feature is enabled using a user-defined universal hardware input pin or via the

device I2C interface. Spread spectrum can be applied to any output clock, with any clock frequency up to 250 MHz. Since the spread

spectrum clock generation is performed in the MultiSynth fractional dividers, the spread spectrum waveform is highly consistent across

process, voltage and temperature. The Si5332 features two independent MultiSynth dividers, enabling the device to provide two inde-

pendent spread profiles simultaneously to the clock output banks.

Spread spectrum is commonly used for 100 MHz PCI Express clock outputs. To comply with the spread spectrum specifications for PCI

Express, the spreading frequency should be set to a maximum of 33 kHz and –0.5% down spread. A universal hardware input pin can

be configured to toggle spread spectrum on/off.

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