Skyworks Solutions Inc. SI5345A-D-GMR

Overview

SI5345A-D-GMR 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 4 differential or LVCMOS inputs and 10 programmable outputs (LVDS/LVPECL/LVCMOS/CML/HCSL), and operates across –40 to +85 °C for SyncE-compliant telecom line cards.

For engineers reviewing the SI5345A-D-GMR datasheet, SI5345A-D-GMR pinout, SI5345A-D-GMR application, or SI5345A-D-GMR equivalent, key selection considerations include its G.8262 EEC Option 1/2 compliance, digitally programmable jitter attenuation bandwidth (0.1 Hz–4 kHz), in-circuit NVM configuration, and support for hitless/ramped/glitchless input switching in OTN, 100G Ethernet, and broadcast video systems.

Technical Context

The SI5345A-D-GMR implements a fourth-generation DSPLL with fully integrated loop filter and digitally configurable loop 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 within specified ranges.

It supports three operational modes-free-run (crystal-referenced), locked (input-synchronized), and holdover (averaged historical frequency)-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% (VDD), analog supply 3.3 V ±5% (VDDA), with independent 1.8/2.5/3.3 V output supply pins.

Key Specifications

Pinout & Package

SI5345A-D-GMR is housed in a 64-pin QFN package (9 × 9 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are validated per Skyworks Si5345 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 SI5345A-D-GMR, Si5345B-D-GMR trades fractional synthesis and extended frequency range for simpler configuration, while LTC6957-3IUF#PBF offers higher-frequency outputs at the cost of reduced channel count, no NVM, and external loop filter dependency - making SI5345A-D-GMR optimal for multi-protocol, field-programmable telecom timing.

Availability

SI5345A-D-GMR is available at Aetrix Electronics and suitable for OTN muxponders, 100GbE line cards, and broadcast video equipment requiring stable component supply, long-term lifecycle assurance, and G.8262-compliant timing performance.

Supply support for SI5345A-D-GMR 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, automotive, and industrial markets.

The Si5345 family is designed specifically for high-performance, multi-protocol jitter attenuation and clock multiplication in carrier-grade networking and broadcast infrastructure - emphasizing G.8262 compliance, field programmability, and robust holdover behavior.

FAQ

What is the primary function of the SI5345A-D-GMR in a telecom timing architecture?

The SI5345A-D-GMR serves as a jitter attenuator and any-frequency clock multiplier, synchronizing to incoming reference clocks (e.g., SyncE or BITS), cleaning their phase noise, and generating up to 10 precisely timed outputs for SerDes, processors, and PHYs. Its DSPLL architecture ensures SI5345A-D-GMR meets ITU-T G.8262 EEC Option 1/2 requirements while supporting hitless switching and holdover during reference loss - critical for carrier-class reliability.

Does the SI5345A-D-GMR support both I²C and SPI interfaces for configuration?

Yes, the SI5345A-D-GMR supports both I²C and SPI serial interfaces for register access and NVM programming. Interface selection is determined by hardware strapping (pins MODE[1:0]) or configuration bits. This dual-interface capability allows flexible integration with microcontrollers (I²C) or FPGAs (SPI), and ClockBuilder Pro software supports both protocols when configuring SI5345A-D-GMR devices.

What crystal frequency is recommended for optimal jitter performance with the SI5345A-D-GMR?

A 48–54 MHz fundamental-mode crystal is recommended for optimal jitter performance with the SI5345A-D-GMR. The device's internal oscillator circuit and integrated load capacitors are optimized for this range, achieving the specified 90 fs rms jitter. Crystals outside this range (e.g., 25–47 MHz) are supported but may increase output jitter; Skyworks specifies worst-case jitter degradation above 100 fs rms below 48 MHz.

How does the SI5345A-D-GMR handle input clock failure in a redundant timing system?

Upon input clock failure, the SI5345A-D-GMR automatically enters holdover mode using up to 120 seconds of stored frequency history to compute an averaged holdover frequency. This minimizes phase disturbance at outputs. The holdover window size and delay are programmable, and SI5345A-D-GMR exits holdover glitchlessly when a valid clock returns - ensuring continuous, deterministic timing in systems like OTN line cards and SyncE switches.

Can the SI5345A-D-GMR generate different output formats simultaneously?

Yes, the SI5345A-D-GMR supports simultaneous LVDS, LVPECL, LVCMOS, CML, and HCSL outputs across its 10 channels. Each output is independently configurable for signal format, amplitude, common-mode voltage (for differential), and drive strength. This eliminates external level translators and simplifies timing distribution in heterogeneous systems - for example, delivering LVDS to FPGAs, LVCMOS to microcontrollers, and HCSL to 100G SerDes, all from a single SI5345A-D-GMR.