Skyworks Solutions Inc. SI5345B-B04408-GMR

Overview

SI5345B-B04408-GMR from Skyworks is a 10-channel, any-frequency jitter attenuator/clock multiplier with fourth-generation DSPLL™ and MultiSynth™ architecture. 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 in SyncE-compliant carrier Ethernet switches and OTN transponders.

For engineers reviewing the SI5345B-B04408-GMR datasheet, SI5345B-B04408-GMR pinout, SI5345B-B04408-GMR application, or SI5345B-B04408-GMR equivalent, key selection considerations include its 0.1–4 kHz digitally programmable jitter attenuation bandwidth, G.8262 EEC Option 1/2 compliance, I²C/SPI configurability with on-chip NVM, and support for LVDS/LVPECL/LVCMOS/CML/HCSL output formats with independent supply pins.

Technical Context

The SI5345B-B04408-GMR implements a fourth-generation DSPLL with fully integrated loop filter and digitally programmable loop bandwidth (0.1 Hz–4 kHz), enabling application-level jitter optimization. Its MultiSynth architecture uses fractional-N synthesis (Mn/Md) and integer-R division to generate any output frequency from any input frequency, with hitless switching between fractionally related inputs.

It features four configurable clock inputs (IN0–IN3), ten independently programmable outputs (OUT0–OUT9), status monitoring (LOS/OOF/LOL), and dual-mode operation: synchronous locking to external references or freerun/holdover using an internal 25–54 MHz crystal oscillator. The device supports ramped holdover exit and glitchless input switching across ±500 ppm frequency offsets.

Key Specifications

Pinout & Package

SI5345B-B04408-GMR is housed in a 64-pin QFN package (9 × 9 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are defined per Skyworks Si5345 Rev D datasheet Section 9 (Pin Descriptions) and Figure 10.1 (Package Diagram).

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5345A-B04408-GMR, SI5345B-B04408-GMR trades maximum output frequency (350 MHz vs. 1028 MHz) for optimized cost and power in sub-350 MHz SyncE/OTN applications, while retaining identical jitter performance, feature set, and pin compatibility. Against LMK04832RHAR, SI5345B-B04408-GMR provides lower jitter (90 fs vs. 110 fs), smaller 64-QFN footprint, and factory-programmable NVM - making it more suitable for space-constrained telecom line cards.

Availability

SI5345B-B04408-GMR is available at Aetrix Electronics and suitable for carrier Ethernet switches, OTN transponders, broadcast video infrastructure, and test equipment requiring stable component supply, long-term lifecycle support, and G.8262-compliant timing performance.

Supply support for SI5345B-B04408-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 wireless, broadband, automotive, and industrial markets.

The Si5345 family is designed specifically for high-performance timing in telecom infrastructure, targeting ITU-T G.8262 SyncE, OTN, and broadcast video applications where ultra-low jitter and robust holdover are mission-critical.

FAQ

What is the maximum output frequency supported by SI5345B-B04408-GMR?

The SI5345B-B04408-GMR supports a maximum differential output frequency of 1028 MHz and a maximum LVCMOS output frequency of 250 MHz. However, its B-grade variant is specified for 0.001–350 MHz output range - meaning full 1028 MHz capability requires the A-grade (Si5345A). This limitation is explicitly defined in Skyworks' Ordering Guide for the Si5345 family. SI5345B-B04408-GMR maintains identical jitter (90 fs rms) and feature set as the A-grade within its 350 MHz range.

Does SI5345B-B04408-GMR require external loop filter components?

No, SI5345B-B04408-GMR integrates the entire DSPLL loop filter on-chip. This eliminates discrete passive components, reduces PCB area, and prevents noise coupling issues common in discrete filter implementations. The loop bandwidth remains digitally programmable from 0.1 Hz to 4 kHz without hardware changes - a key differentiator from legacy PLL-based jitter cleaners that rely on external RC networks.

How does SI5345B-B04408-GMR achieve ITU-T G.8262 compliance?

SI5345B-B04408-GMR meets G.8262 EEC Option 1 and Option 2 specifications through its combination of ultra-low 90 fs rms jitter, digitally programmable loop bandwidth (0.1–4 kHz), and advanced holdover algorithm using 120-second frequency history averaging. Its DSPLL architecture suppresses input jitter while maintaining wander performance under holdover - satisfying both short-term jitter and long-term wander requirements defined in G.8262 for SyncE applications.

Can SI5345B-B04408-GMR operate without an external crystal?

No, SI5345B-B04408-GMR requires an external 25–54 MHz fundamental-mode crystal connected to XA/XB pins for freerun and holdover mode stability. While it accepts external REFCLK on XA/XB (bypassing the crystal oscillator), Skyworks specifies that optimal jitter performance - especially for SyncE pizza-box applications - demands a crystal. Internal load capacitors eliminate need for external caps, simplifying design.

Is SI5345B-B04408-GMR pin-compatible with other Si5345 variants?

Yes, SI5345B-B04408-GMR is fully pin-compatible with all Si5345 variants (A/C/D grades) in the 64-QFN 9×9 mm package. Differences between grades (e.g., A vs. B) relate solely to output frequency range and synthesis mode support - not pinout, package, or electrical interface. This allows drop-in replacement during design iteration or cost optimization without PCB changes.