Silicon Laboratories SI5351A/B/C Replacing a Crystal with a Clock, Hcsl Compatible Outputs

Models: SI5351A/B/C

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Si5351A/B/C

5.6. Replacing a Crystal with a Clock

The Si5351 can be driven with a clock signal through the XA input pin.

VIN = 1 VPP

 

 

 

 

25/27 MHz

 

 

XA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0.1 µF

XB

Note: Float the XB input while driving the XA input with a clock

OSC

PLLA

PLLB

Multi

Synth

0

Multi

Synth

1

Multi

Synth

N

Figure 16. Si5351 Driven by a Clock Signal

5.7. HCSL Compatible Outputs

The Si5351 can be configured to support HCSL compatible swing when the VDDO of the output pair of interest is set to 2.5 V (i.e., VDDOA must be 2.5 V when using CLK0/1; VDDOB must be 2.5 V for CLK2/3 and so on).

The circuit in the figure below must be applied to each of the two clocks used, and one of the clocks in the pair must also be inverted to generate a differential pair. See register setting CLKx_INV.

OSC

PLLA

PLLB

Multi

Synth

0

Multi

Synth

1

Multi

Synth

N

ZO = 70 Ω

R1

0 Ω

511 Ω

240 Ω R2

ZO = 70 Ω

R1

0 Ω

511 Ω

240 Ω R2

Note: The complementary -180 degree out of phase output clock is generated using the INV function

HCSL CLKIN

Figure 17. Si5350C Output is HCSL Compatible

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Preliminary Rev. 0.95

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Silicon Laboratories SI5351A/B/C specifications Replacing a Crystal with a Clock, Hcsl Compatible Outputs

SI5351A/B/C specifications

Silicon Laboratories SI5351A/B/C is a versatile, low-power clock generator and frequency synthesizer that has gained widespread popularity in various applications, including telecommunications, consumer electronics, and industrial control systems. These devices are primarily designed to provide precise clock frequency generation with low phase noise and jitter, making them ideal for high-performance applications.

One of the standout features of the SI5351 is its ability to generate multiple output frequencies simultaneously. Capable of producing up to three independent programmable outputs, the SI5351A/B/C can generate frequencies ranging from 8 kHz to 160 MHz. With its integrated phase-locked loop (PLL) technology, it achieves excellent frequency stability and accuracy, simplifying the design of frequency-dependent systems.

The device operates under a supply voltage range of 1.8V to 3.6V, allowing it to be used in battery-powered applications without excessive power consumption. The SI5351’s low current draw, typically as low as 25 mA, is especially beneficial in portable devices, extending battery life and enhancing overall efficiency. Furthermore, it features a programmable output driver, which can be set to various drive strengths, ensuring compatibility with a wide array of load requirements.

Configuration and control of the SI5351 are user-friendly, implemented via an I2C interface. This allows for straightforward integration into microcontroller-based designs. Moreover, the device includes an on-chip memory that stores settings, which streamlines the reconfiguration process when power cycling, minimizing setup time for developers.

Another significant advantage of the SI5351A/B/C is its output jitter performance, which is typically below 1 ps, resulting in clean output signals essential for high-speed data communications and precise timing applications. The SI5351’s integration of multiple synthesizer stages contributes to its impressive phase noise characteristics, making it suitable for demanding RF applications.

Additionally, the SI5351 devices offer programmable frequency stepping, allowing users to define custom frequency increments, which is particularly useful in applications requiring precise tuning or modulation. This flexibility, combined with its compact size and simple interface, makes the SI5351A/B/C an ideal choice for engineers seeking a reliable, cost-effective solution for generating clock signals in a myriad of electronic systems.

In summary, Silicon Laboratories SI5351A/B/C provides a robust, low-power solution for high-precision clock generation, characterized by its programmable outputs, low jitter, easy configurability, and broad frequency range, making it an excellent choice for both commercial and industrial applications across various sectors.