Skyworks Solutions Inc. SI5345A-B05746-GM

Overview

SI5345A-B05746-GM from Skyworks is a 10-channel, any-frequency jitter attenuator/clock multiplier featuring fourth-generation DSPLL™ and MultiSynth™ architectures. It delivers ultra-low 90 fs rms jitter, supports differential inputs up to 750 MHz and outputs up to 1028 MHz, and operates in free-run, locked, or holdover modes - deployed in OTN transponders and SyncE-compliant carrier Ethernet switches.

For engineers reviewing the SI5345A-B05746-GM datasheet, SI5345A-B05746-GM pinout, SI5345A-B05746-GM application, or SI5345A-B05746-GM equivalent, key selection criteria include programmable jitter attenuation bandwidth (0.1 Hz–4 kHz), G.8262 EEC Option 1/2 compliance, hitless input switching, DCO mode with 0.001 ppb step size, and factory preprogrammed NVM configuration for known-power-up behavior.

Technical Context

The SI5345A-B05746-GM implements a digitally controlled DSPLL loop with fully integrated on-chip loop filter and programmable bandwidth (0.1 Hz–4 kHz), enabling precise jitter filtering without external components. Its MultiSynth architecture uses fractional-N synthesis (Mn/Md) and integer-R division to generate any output frequency from any input frequency across 10 independent outputs.

It supports four differential or LVCMOS inputs (IN0–IN3), automatic/manual clock switching with hitless and ramped transition modes, status monitoring (LOS/OOF/LOL), and dual-reference operation via external 25–54 MHz crystal (XA/XB) or REFCLK - all managed via I²C/SPI interface with in-circuit programmable OTP memory.

Key Specifications

Pinout & Package

The SI5345A-B05746-GM is housed in a 64-QFN package (9×9 mm, 0.5 mm pitch) with exposed thermal pad, rated for –40°C to +85°C operation and RoHS-6 compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5345B-D-GM and LTC6957-3, the SI5345A-B05746-GM uniquely combines 10 configurable outputs, full G.8262 EEC Option 1/2 compliance, on-chip NVM for known-power-up behavior, and 1028 MHz output capability - making it the only option qualified for high-density OTN and SyncE line card deployments requiring field-upgradable timing plans.

Availability

SI5345A-B05746-GM is available at Aetrix Electronics and suitable for OTN transponders, SyncE carrier switches, broadcast video infrastructure, and test equipment requiring stable component supply, long-term lifecycle assurance, and factory-programmed configuration traceability.

Supply support for SI5345A-B05746-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 technologies.

The Si5345 family is designed specifically for high-performance timing in telecom infrastructure, enterprise networking, and broadcast systems - emphasizing jitter attenuation, multi-frequency flexibility, and standards compliance (ITU-T G.8262, Telcordia GR-1244).

FAQ

What is the primary function of the SI5345A-B05746-GM in a telecom timing system?

The SI5345A-B05746-GM serves as a jitter attenuating clock multiplier that cleans and regenerates timing signals in telecom infrastructure. It locks to noisy or unstable input references (e.g., from packet networks), suppresses jitter via its digitally programmable DSPLL, and generates multiple low-jitter output clocks - all while maintaining G.8262 EEC Option 1/2 compliance. The SI5345A-B05746-GM is factory preprogrammed to deliver specific frequencies upon power-up, eliminating boot-time configuration delays in mission-critical line cards.

Does the SI5345A-B05746-GM support automatic failover between input clocks?

Yes, the SI5345A-B05746-GM supports both automatic and manual input clock switching. Its internal state machine monitors all four inputs (IN0–IN3) for validity (LOS/OOF), applies user-defined priority ordering, and performs hitless or ramped transitions based on configuration. When the active input fails, the device seamlessly switches to the next valid input - or enters holdover mode if none are available - ensuring uninterrupted timing in carrier-grade systems. This behavior is fully implemented within the SI5345A-B05746-GM without external logic.

Can the SI5345A-B05746-GM operate without an external crystal?

No - the SI5345A-B05746-GM requires an external 25–54 MHz crystal connected to XA/XB pins for stable free-run and holdover operation. While it can accept an external REFCLK instead of a crystal, doing so disables internal load capacitors and mandates careful signal integrity design. For optimal jitter performance and simplified BOM, Skyworks specifies a crystal (not REFCLK) as the recommended reference source. The SI5345A-B05746-GM's oscillator circuit relies on this reference to maintain frequency accuracy during lock loss.

How does the SI5345A-B05746-GM achieve 90 fs rms jitter performance?

The SI5345A-B05746-GM achieves 90 fs rms jitter through fourth-generation DSPLL architecture with fully integrated loop filter, optimized VCO design, and low-noise MultiSynth fractional synthesis. Its jitter attenuation bandwidth is digitally programmable (0.1 Hz–4 kHz), allowing precise trade-offs between wander rejection and jitter filtering. Internal power supply regulation, differential signaling paths, and crystal-optimized layout further reduce noise coupling. This 90 fs rms value is measured per IEEE 1139 at 12 kHz–20 MHz offset and is guaranteed across temperature for the SI5345A-B05746-GM.

Is the SI5345A-B05746-GM pin-compatible with other Si5345 variants?

Yes - the SI5345A-B05746-GM shares identical 64-QFN (9×9 mm) packaging, pin assignment, and electrical interface with all Si5345 variants (e.g., Si5345A-D-GM, Si5345B-D-GM). Differences lie solely in factory-programmed configuration (frequency plan, NVM settings) and specified output frequency range (1028 MHz for SI5345A-B05746-GM vs. 350 MHz for Si5345B-D-GM). No PCB redesign is needed when migrating between Si5345A-B05746-GM and other Si5345A-grade devices with matching package code.