Skyworks Solutions Inc. SI5344B-B05421-GM

Overview

SI5344B-B05421-GM from Skyworks is a 4-input, 4-output jitter attenuator/clock multiplier featuring fourth-generation DSPLL™ and MultiSynth™ technology. It delivers ultra-low 90 fs rms jitter, supports differential input frequencies up to 750 MHz and LVCMOS inputs up to 250 MHz, and generates output frequencies from 100 Hz to 350 MHz (integer-only mode). It is deployed in carrier-grade Synchronous Ethernet line cards requiring ITU-T G.8262 EEC Option 1/2 compliance.

For engineers reviewing the SI5344B-B05421-GM datasheet, SI5344B-B05421-GM pinout, SI5344B-B05421-GM application, or SI5344B-B05421-GM equivalent, key selection considerations include its 350 MHz integer-only output limit, 44-QFN 7×7 mm package, programmable jitter attenuation bandwidth (0.1 Hz–4 kHz), G.8262 SyncE compliance, and support for hitless/ramped/glitchless input switching in telecom timing systems.

Technical Context

The SI5344B-B05421-GM implements a digitally controlled DSPLL with fully integrated loop filter and programmable loop bandwidth (0.1 Hz–4 kHz), enabling precise jitter filtering and holdover stability. Its MultiSynth architecture uses integer-only frequency synthesis (no fractional-N) to generate up to four independent output clocks from any of four selectable inputs.

It operates across freerun, locked, holdover, and zero-delay modes, with automatic/manual input switching, status monitoring (LOS/OOF/LOL), and DCO mode offering 0.001 ppb step resolution. Core supply is 1.8 V ±5%, analog supply 3.3 V ±5%, and output supplies are independently configurable at 3.3 V, 2.5 V, or 1.8 V.

Key Specifications

Pinout & Package

The SI5344B-B05421-GM is housed in a 44-pin QFN package (7×7 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are defined per Skyworks' Si5344 Rev D datasheet Section 9 (Pin Descriptions).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar jitter attenuator applications.

Compared with SI5344B-B05421-GM, the SI5344A-B05421-GM adds fractional synthesis headroom for complex clock trees, while the SI5342B-B05421-GM retains full timing performance in a lower-channel-count form factor-both share identical pinout, temperature range, and SyncE compliance.

Availability

SI5344B-B05421-GM is available at Aetrix Electronics and suitable for carrier Ethernet switches, OTN line cards, broadcast infrastructure, and test equipment requiring stable component supply, long-term lifecycle assurance, and G.8262-compliant timing performance.

Supply support for SI5344B-B05421-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 for communications, industrial, and automotive markets.

The Si5344 family is designed specifically for high-reliability telecom and networking timing applications demanding ultra-low jitter, robust holdover, and ITU-T G.8262 compliance in compact form factors.

FAQ

What is the maximum output frequency supported by the SI5344B-B05421-GM?

The SI5344B-B05421-GM supports a maximum output frequency of 350 MHz. This limit arises because the "B" suffix denotes integer-only frequency synthesis mode, which restricts output generation to whole-number multiples of reference frequencies-unlike fractional variants (e.g., SI5344A) that extend to 1028 MHz. The 350 MHz ceiling is verified in Skyworks' Si5345/44/42 Rev D Ordering Guide and Electrical Specifications tables.

Does the SI5344B-B05421-GM meet ITU-T G.8262 requirements for Synchronous Ethernet?

Yes, the SI5344B-B05421-GM meets ITU-T G.8262 EEC Option 1 and Option 2 specifications. Its 90 fs rms jitter performance, programmable jitter attenuation bandwidth (0.1 Hz–4 kHz), and holdover stability with historical averaging directly satisfy wander and jitter transfer requirements for SyncE applications. This compliance is explicitly stated in the Si5345/44/42 Rev D Data Sheet Features List and Functional Description sections.

What package type and pin count does the SI5344B-B05421-GM use?

The SI5344B-B05421-GM uses a 44-pin QFN package measuring 7×7 mm with 0.5 mm pitch and an exposed thermal pad. This matches the mechanical outline specified in Skyworks' Si5345/44/42 Rev D Data Sheet Section 10.2. The pinout is identical to other Si5344 variants (e.g., SI5344A, SI5344C), enabling drop-in replacement within the same family when electrical requirements align.

Can the SI5344B-B05421-GM operate without an external crystal?

No-the SI5344B-B05421-GM requires an external crystal (25–54 MHz) connected to XA/XB pins for stable freerun and holdover operation. While it accepts external REFCLK on XA/XB, the datasheet specifies that optimal jitter performance and SyncE-compliant holdover demand a crystal (or TCXO/OCXO). Internal oscillator circuitry depends on this reference; no internal RC oscillator is provided.

How does the SI5344B-B05421-GM handle input clock failures in carrier-grade systems?

The SI5344B-B05421-GM enters holdover mode upon input failure, using up to 120 seconds of stored historical frequency data to compute an averaged holdover frequency. This minimizes phase transients and maintains sub-100 ppb accuracy during reference outages-critical for maintaining SyncE compliance. The holdover window size and delay are programmable via register, and exit can be ramped to avoid glitches, as confirmed in Section 3.4.5 of the Rev D datasheet.