Skyworks Solutions Inc. SI5351B-B04462-GM

Overview

SI5351B-B04462-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 embedded timing applications. It delivers up to eight independent non-integer-related frequencies from 2.5 kHz to 200 MHz per output, supports 0 ppm synthesis error, operates from a 25 or 27 MHz crystal, and features configurable output voltages (1.8/2.5/3.3 V) for mixed-voltage system interfacing.

For engineers reviewing the SI5351B-B04462-GM datasheet, SI5351B-B04462-GM pinout, SI5351B-B04462-GM application, or SI5351B-B04462-GM equivalent, key selection criteria include VCXO tuning range (±240 ppm at 3.3 V), low period jitter (<70 ps pk-pk), I²C programmability, 20-QFN package compatibility, and support for HCSL-compatible swing and spread spectrum modulation.

Technical Context

The SI5351B-B04462-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. Each PLL feeds eight independent MultiSynth fractional dividers, enabling simultaneous generation of asynchronous or synchronous outputs with static phase offset control and glitchless frequency transitions.

It supports three distinct input configurations - crystal-only (XTAL), crystal + VC control voltage (VCXO mode), or external clock (CLKIN) - but SI5351B-B04462-GM specifically enables VCXO operation via its dedicated VC pin, with tunable gain (18–150 ppm/V) and ±5% linearity over 10–90% VDD range. Output drive strength, rise/fall time, and spread spectrum are individually configurable per channel.

Key Specifications

Pinout & Package

SI5351B-B04462-GM is housed in a 20-pin QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments follow the Si5351B 20-QFN configuration per Skyworks datasheet 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-B04462-GM, Si5351A-B-GM omits VCXO capability entirely, limiting tuning flexibility, while Si5351C-B-GM replaces VC with CLKIN-enabling external reference locking but removing analog voltage control. SI5351B-B04462-GM uniquely balances crystal-based stability with analog tunability for closed-loop timing systems.

Availability

SI5351B-B04462-GM is available at Aetrix Electronics and suitable for networking equipment, industrial embedded controllers, laser rangefinders, and audio/video timing applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SI5351B-B04462-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 precision analog products.

The Si5351 family is engineered for flexible, low-cost clock generation in space-constrained, cost-sensitive applications-including consumer electronics, industrial controls, and communications infrastructure-where replacing multiple discrete timing components with a single programmable device improves reliability and reduces bill-of-materials complexity.

FAQ

What is the maximum number of unique frequencies above 112.5 MHz that SI5351B-B04462-GM can generate simultaneously?

SI5351B-B04462-GM supports exactly two unique frequencies above 112.5 MHz at the same time-for example, 125 MHz on CLK0 and 130 MHz on CLK1. Additional outputs may replicate those frequencies (e.g., 125 MHz on CLK0–CLK3), but no third distinct frequency >112.5 MHz is permitted. This limitation arises from internal PLL bandwidth and MultiSynth resource allocation in the Si5351B-B04462-GM architecture.

Does SI5351B-B04462-GM require external load capacitors for the 25 MHz crystal?

SI5351B-B04462-GM includes programmable internal load capacitance (0, 6, 8, or 10 pF) and typically does not require external load capacitors for standard 25 MHz or 27 MHz AT-cut crystals. If the crystal specifies 12 pF load capacitance, up to 2 pF total external capacitance (e.g., 4 pF split across XA/XB) may be added-but this is explicitly noted in Skyworks AN551 and confirmed in the SI5351B-B04462-GM datasheet Rev. 1.3.

Can SI5351B-B04462-GM operate with a 2.5 V core supply voltage?

Yes, SI5351B-B04462-GM supports core supply voltage (VDD) of 2.25–2.75 V, including 2.5 V nominal operation. However, VCXO performance (pull range and gain) is specified only at 3.3 V VDD per Table 5; for 2.5 V VCXO use, direct consultation with Skyworks Solutions is required as it is not characterized in the published datasheet.

How is spread spectrum modulation configured on SI5351B-B04462-GM?

Spread spectrum modulation on SI5351B-B04462-GM is configured independently per output via I²C register writes. Down-spread (–0.1% to –2.5%) or center-spread (±0.1% to ±1.5%) is selectable in 0.1% increments, with a fixed 31.5 kHz modulation rate. The feature is enabled per CLKx using the Spread Spectrum Enable bits in the corresponding MultiSynth configuration registers.

What is the thermal resistance (θJA) of SI5351B-B04462-GM in still air on a 4-layer PCB?

For SI5351B-B04462-GM in its 20-QFN package, the junction-to-ambient thermal resistance (θJA) is 41 °C/W under still-air conditions on a 4-layer PCB per JESD51-2A/5/7 standards. This value assumes proper thermal pad soldering and recommended land pattern per Skyworks datasheet Section 12.2.