Skyworks Solutions Inc. SI5401A-A15682-GM

Overview

SI5401A-A15682-GM from Skyworks is a NetSync™ Network Synchronizer clock IC with three DSPLLs, one MultiSyth fractional divider, and 10 programmable outputs. It delivers ultra-low 51 fs RMS jitter (12 kHz–20 MHz at 312.5 MHz), supports ITU-T G.8273.2/T-BC compliance, and enables IEEE 1588 phase/frequency lock via PPSPLL with 1 ppt DCO resolution for 5G O-RAN distributed unit timing.

For engineers reviewing the SI5401A-A15682-GM datasheet, SI5401A-A15682-GM pinout, SI5401A-A15682-GM application, or SI5401A-A15682-GM equivalent, key selection criteria include SyncE wander filtering, hitless 1PPS/PP2S switching (<150 ps transient), programmable output delay (±10 ns), multi-supply support (1.8 V/2.5 V/3.3 V), and I²C/SPI in-circuit programming with non-volatile memory.

Technical Context

The SI5401A-A15682-GM integrates three independent PLLs: REFPLL for external crystal/TCXO reference stability and holdover, DSPLL A/B for network synchronization with auto-switching between Free-Run/Holdover/Locked modes, and PPSPLL dedicated to 1PPS/PP2S inputs for IEEE 1588 grandmaster operation. Its architecture supports simultaneous frequency lock to high-speed clocks and phase lock to pulse inputs.

It implements fifth-generation DSPLL® and MultiSyth™ technologies with selectable jitter attenuation bandwidth (10 Hz–4 kHz), programmable loop bandwidth (1 mHz–25 mHz), and adaptive phase pull-in rate control. Output formats include LVDS, LVCMOS, HCSL, CML, and AC-coupled LVPECL across 10 pins, each with ±50 ps output-output skew and zero-delay mode capability.

Key Specifications

Pinout & Package

SI5401A-A15682-GM is housed in a 72-lead QFN package (10 mm × 10 mm, 0.5 mm pitch) with exposed thermal pad. The package supports –40 °C to +95 °C ambient operation and complies with JEDEC MO-220 and RoHS standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar network synchronizer applications.

Compared with Si5402A-A15681-GM and LMK5B33414RGZT, the SI5401A-A15682-GM offers optimal balance of IEEE 1588 servo precision (1 ppt), SyncE compliance, and compact 10-output footprint-making it ideal for space-constrained O-DU and FHGWS designs where full redundancy is not required.

Availability

SI5401A-A15682-GM is available at Aetrix Electronics and suitable for 5G O-RAN distributed units, IEEE 1588 boundary clocks, and front-haul gateway switches requiring stable component supply, long-term lifecycle support, and verified telecom-grade timing performance.

Supply support for SI5401A-A15682-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, Inc. is a global leader in analog and mixed-signal semiconductors, specializing in RF, timing, and connectivity solutions for wireless infrastructure, automotive, and industrial markets.

The Si540x product line was engineered specifically for wireline telecom timing, delivering integrated SyncE wander filtering, IEEE 1588 phase servo capability, and ultra-low jitter in a single chip - reducing system complexity in 5G and cloud networking equipment.

FAQ

What is the primary timing function of the SI5401A-A15682-GM in 5G O-RAN systems?

The SI5401A-A15682-GM serves as the core network synchronizer in O-RAN Distributed Units, providing phase-aligned, ultra-low-jitter clocks (e.g., 245.76 MHz and 30.72 MHz) with programmable delay and hitless switching. Its PPSPLL locks to 1PPS inputs while DSPLL A/B maintain SyncE compliance, enabling deterministic fronthaul timing per O-RAN WG4 specifications. SI5401A-A15682-GM supports both T-BC and T-TSC profiles per ITU-T G.8273.2.

Does the SI5401A-A15682-GM require external loop filters for PLL operation?

No, the SI5401A-A15682-GM does not require external loop filters due to its integrated fifth-generation DSPLL® architecture with on-chip charge pump and filter components. This eliminates discrete RC networks, reduces PCB area, and improves reliability. SI5401A-A15682-GM maintains stable lock and low jitter across temperature and supply variations without external compensation.

What serial interface options does the SI5401A-A15682-GM support for configuration?

The SI5401A-A15682-GM supports both I²C (two-wire) and SPI (three- or four-wire) interfaces for in-circuit programming and real-time status monitoring. Configuration is stored in non-volatile memory, allowing autonomous boot without host intervention. SI5401A-A15682-GM is fully compatible with Skyworks' ClockBuilder Pro™ software for GUI-based register setup and validation.

How does the SI5401A-A15682-GM meet ITU-T G.8273.2 compliance for telecom timing?

The SI5401A-A15682-GM meets ITU-T G.8273.2 T-BC and T-TSC requirements through its dual-reference DSPLL architecture, programmable loop bandwidth (1 mHz–4 kHz), SyncE-compliant wander filtering, and automatic Free-Run/Holdover/Locked mode transitions. SI5401A-A15682-GM achieves <100 ns max time error during holdover and supports phase slope limiting for controlled transient response under network stress.

Can the SI5401A-A15682-GM generate both integer and fractional output frequencies?

Yes, the SI5401A-A15682-GM supports integer division up to 1.2288 GHz and fractional synthesis up to 650 MHz using its dedicated MultiSyth™ divider. This enables precise generation of non-harmonic frequencies required for IEEE 1588 servo loops (e.g., 10 MHz ± ppm offsets) and legacy telecom rates (e.g., 2.048 MHz, 8.192 MHz). SI5401A-A15682-GM applies the same jitter performance across both modes.