Skyworks Solutions Inc. SI5351B-B04759-GM

Overview

SI5351B-B04759-GM from Skyworks Solutions is an I²C-programmable 8-output CMOS clock generator with integrated VCXO, designed to replace crystals, crystal oscillators, and voltage-controlled oscillators in cost-sensitive timing applications. It delivers up to eight non-integer-related frequencies from 2.5 kHz to 200 MHz per output, supports 0 ppm frequency synthesis error, and operates from a 25 or 27 MHz fixed-frequency crystal. It is used in networking equipment, residential gateways, and audio/video systems requiring flexible, synchronized clocking.

For engineers reviewing the SI5351B-B04759-GM datasheet, SI5351B-B04759-GM pinout, SI5351B-B04759-GM application, or SI5351B-B04759-GM equivalent, key selection criteria include its VCXO tuning range (±240 ppm at 3.3 V), low period jitter (< 70 ps pk-pk), independent output voltage supplies (1.8/2.5/3.3 V), and support for glitchless frequency changes and static phase offset control.

Technical Context

The SI5351B-B04759-GM implements a dual-PLL architecture: PLL A accepts either XTAL or CLKIN input, while PLL B functions as a highly linear VCXO locked to the same crystal reference. Both PLLs feed eight independent MultiSynth fractional dividers, enabling arbitrary frequency synthesis per output without integer constraints.

It features separate VDDO pins (VDDOA–VDDOD) for level-translated outputs, configurable rise/fall time control, spread spectrum modulation (±0.1% to ±1.5%), and programmable output delay. The VCXO gain is configurable from 18 to 150 ppm/V, with linearity maintained across 10–90% of VDD.

Key Specifications

Pinout & Package

SI5351B-B04759-GM is housed in a 20-pin QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments are validated per Skyworks Si5351B 20-QFN pinout specification (Rev. 1.3, Section 10.2).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar clock generator applications.

Compared with SI5351B-B04759-GM, Si5351A-B-GM lacks VCXO functionality and cannot provide voltage-controlled tuning, while Si5351C-B-GM replaces the VC pin with CLKIN support-making it suitable for externally referenced synchronization but not for analog tuning applications.

Availability

SI5351B-B04759-GM is available at Aetrix Electronics and suitable for networking equipment, audio/video systems, and industrial instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SI5351B-B04759-GM includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Skyworks Solutions is a global semiconductor company specializing in analog and mixed-signal connectivity solutions, with leadership in RF, timing, and power management ICs.

The SI5351 family was designed to replace discrete timing components-including crystals, oscillators, VCXOs, and PLLs-in cost- and space-constrained embedded systems, targeting consumer, networking, and industrial applications.

FAQ

What is the primary function of the SI5351B-B04759-GM?

The SI5351B-B04759-GM is an I²C-programmable 8-output CMOS clock generator with integrated VCXO. Its primary function is to synthesize precise, non-integer-related clock frequencies (2.5 kHz–200 MHz) from a single 25 or 27 MHz crystal, replacing multiple discrete oscillators and enabling flexible, software-configurable timing in embedded systems.

Does the SI5351B-B04759-GM require an external crystal?

Yes, the SI5351B-B04759-GM requires an external 25 MHz or 27 MHz AT-cut crystal connected to XA/XB pins. It does not operate from an external clock input (CLKIN) - that functionality is reserved for the Si5351C variant. The crystal serves as the base reference for both the internal oscillator and the VCXO circuitry within the SI5351B-B04759-GM.

What is the maximum VCXO tuning range supported by the SI5351B-B04759-GM?

The SI5351B-B04759-GM supports a configurable VCXO pull range of ±240 ppm at 3.3 V supply voltage, as specified in Table 5 of the Skyworks datasheet (Rev. 1.3). This range is achieved with high linearity (±5%) across 10–90% of VDD and eliminates the need for expensive custom pullable crystals in timing-critical applications.

Can the SI5351B-B04759-GM generate more than two frequencies above 112.5 MHz simultaneously?

No. The SI5351B-B04759-GM can output only two *unique* frequencies above 112.5 MHz at once (e.g., 125 MHz and 130 MHz), as stated in Table 7 footnote 1 and Section 4.2. However, multiple outputs may replicate the same high-frequency value - for example, four outputs at 125 MHz and four at 130 MHz is permitted, but 125 MHz, 130 MHz, and 150 MHz simultaneously is not.

How many independent voltage domains does the SI5351B-B04759-GM support for its outputs?

The SI5351B-B04759-GM supports four independent output voltage domains via VDDOA, VDDOB, VDDOC, and VDDOD pins. Each domain powers two outputs (e.g., VDDOA powers CLK0/CLK1), enabling simultaneous 1.8 V, 2.5 V, and 3.3 V CMOS-level clock signals without external level shifters - a key feature confirmed in the "Separate voltage supply pins" bullet and Table 3 of the datasheet.