Skyworks Solutions Inc. SI5345A-B03273-GM

Overview

SI5345A-B03273-GM from Skyworks is a 10-channel, any-frequency jitter attenuator and clock multiplier IC 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 - enabling precise timing for OTN transponders and SyncE-compliant carrier Ethernet switches.

For engineers reviewing the SI5345A-B03273-GM datasheet, SI5345A-B03273-GM pinout, SI5345A-B03273-GM application, or SI5345A-B03273-GM equivalent, key selection considerations include its G.8262 EEC Option 1/2 compliance, programmable jitter attenuation bandwidth (0.1 Hz–4 kHz), I²C/SPI configurability with on-chip NVM, and support for LVDS/LVPECL/LVCMOS/CML/HCSL output formats with independent supply rails.

Technical Context

The SI5345A-B03273-GM implements a digitally controlled DSPLL with fractional input dividers (P) and MultiSynth output dividers (N/R) to enable hitless switching between fractionally related input clocks and glitchless on-the-fly output frequency changes. Its integrated loop filter eliminates external passive components while supporting programmable loop bandwidths from 0.1 Hz to 4 kHz.

It features automatic and manual input clock selection across four inputs (IN0–IN3), status monitoring (LOS/OOF/LOL), ramped holdover exit, DCO mode with 0.001 ppb step size, and zero-delay mode where IN3 serves as FB_IN. Core voltage is 1.8 V ±5%, analog supply is 3.3 V ±5%, and output supplies are independently configurable at 1.8 V, 2.5 V, or 3.3 V.

Key Specifications

Pinout & Package

The SI5345A-B03273-GM is housed in a 64-pin QFN package (9 mm × 9 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions align with the Si5345 family's standardized layout per Skyworks' Pin Descriptions section (Rev D datasheet, p.45).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SI5345A-B03273-GM, the Si5345B variant trades maximum frequency and fractional synthesis for cost reduction in bandwidth-limited deployments, while the LTC6957 offers simpler integration at the expense of channel count, jitter performance, and autonomous operation - making SI5345A-B03273-GM the sole choice for multi-gigabit telecom timing requiring G.8262 compliance and field-programmable flexibility.

Availability

SI5345A-B03273-GM is available at Aetrix Electronics and suitable for OTN transponders, Synchronous Ethernet switches, and broadcast video infrastructure requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SI5345A-B03273-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 wireless, broadband, automotive, and industrial markets.

The Si5345 family is engineered for high-performance timing in carrier-grade networking and precision instrumentation, delivering jitter attenuation, multi-rate clock multiplication, and robust holdover - all within a single programmable IC.

FAQ

What is the primary function of the SI5345A-B03273-GM in a telecom timing architecture?

The SI5345A-B03273-GM serves as a jitter-attenuating clock multiplier that cleans and regenerates timing signals for synchronization-critical systems. In telecom applications, it locks to a degraded line reference (e.g., from a fiber link), attenuates accumulated jitter and wander, and generates multiple low-jitter output clocks - enabling SI5345A-B03273-GM to meet ITU-T G.8262 EEC Option 1/2 for Synchronous Ethernet and G.783 for OTN.

Does the SI5345A-B03273-GM support both I²C and SPI interfaces, and are they mutually exclusive?

Yes, the SI5345A-B03273-GM supports both I²C and SPI serial interfaces for configuration and monitoring, and they are not mutually exclusive - either can be used independently based on system design preference. The interface is selected via hardware strapping (pins) or register configuration. SI5345A-B03273-GM retains its programmed settings in on-chip NVM, so configuration persists across power cycles regardless of interface choice.

How does the holdover functionality of the SI5345A-B03273-GM maintain timing integrity during input clock loss?

The SI5345A-B03273-GM stores up to 120 seconds of historical frequency data while locked and calculates an averaged holdover frequency from a programmable window within that history. This minimizes phase disturbance during input failure. SI5345A-B03273-GM then uses the external crystal (25–54 MHz on XA/XB) as its reference to sustain output stability - achieving typical holdover accuracy of ±0.1 ppm over 24 hours when paired with a TCXO.

Can the SI5345A-B03273-GM generate different output formats simultaneously, such as LVDS and LVCMOS?

Yes, the SI5345A-B03273-GM supports simultaneous mixed-format outputs: each of its 10 outputs can be independently configured for LVDS, LVPECL, CML, HCSL, or LVCMOS with programmable amplitude and common-mode voltage. Output banks have separate supply pins (VDDOx), allowing SI5345A-B03273-GM to drive 1.8 V, 2.5 V, or 3.3 V logic families concurrently without external level shifters.

Is factory preprogramming available for the SI5345A-B03273-GM, and what does the "B03273" suffix indicate?

Yes, Skyworks offers factory preprogramming for SI5345A-B03273-GM using ClockBuilder Pro software; the "B03273" segment in the part number identifies a unique configuration ID assigned during preprogramming. SI5345A-B03273-GM ships with that exact frequency plan stored in NVM, eliminating field programming - ideal for high-volume deployments requiring guaranteed startup behavior and reduced qualification overhead.