Skyworks Solutions Inc. SI5351A-B06486-GTR

Overview

SI5351A-B06486-GTR from Skyworks Solutions is an I²C-programmable, 8-output CMOS clock generator with integrated VCXO, designed to replace crystals, crystal oscillators, and discrete PLLs in cost-sensitive embedded systems. It delivers up to eight independent, non-integer-related frequencies from 2.5 kHz to 200 MHz with 0 ppm synthesis error, operates from a 25/27 MHz crystal, and supports 1.8/2.5/3.3 V output voltage levels per bank for mixed-signal timing in networking and audio/video equipment.

For engineers reviewing the SI5351A-B06486-GTR datasheet, SI5351A-B06486-GTR pinout, SI5351A-B06486-GTR application, or SI5351A-B06486-GTR equivalent, this device offers precise multi-frequency synthesis, programmable spread spectrum, glitchless frequency switching, static phase offset control, and configurable rise/fall times - all critical for PCIe Gen 1–compliant clocking, HCSL-compatible interfaces, and low-jitter system synchronization.

Technical Context

The SI5351A-B06486-GTR implements a dual-PLL architecture (PLLA + PLLB) with high-resolution MultiSynth fractional dividers per output, enabling independent frequency synthesis on all eight outputs. Its VCXO path uses a highly linear tuning curve (±5% linearity, 18–150 ppm/V gain) referenced to the same 25/27 MHz crystal, eliminating external pullable crystals while maintaining ±240 ppm total pull range.

Each output features separate VDDO supply pins (1.8/2.5/3.3 V), programmable drive strength, and adjustable delay. The device supports I²C configuration at up to 400 kbps, includes OEB (output enable) and SSEN (spread spectrum enable) control pins, and achieves <70 ps pk-pk period jitter (typ.) under full 8-output load with default drive strength.

Key Specifications

Pinout & Package

SI5351A-B06486-GTR is housed in a 20-pin QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin functions are defined per Skyworks Rev. 1.3 datasheet Section 10.1 (Si5351A 20-pin QFN).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar clock generator applications.

Compared with SI5351B-B-GM and SI5351C-B-GM, SI5351A-B06486-GTR provides the simplest crystal-replacement solution with no VC or CLKIN dependencies - reducing design validation effort, component count, and layout sensitivity while retaining full 8-output programmability and 0 ppm synthesis accuracy.

Availability

SI5351A-B06486-GTR is available at Aetrix Electronics and suitable for networking equipment, audio/video timing systems, and industrial instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SI5351A-B06486-GTR 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 leader in analog and mixed-signal semiconductors, specializing in RF, timing, and connectivity solutions for wireless infrastructure, automotive, and industrial markets.

The SI5351A-B06486-GTR belongs to Skyworks' Si5351 family of I²C-programmable clock generators, engineered specifically to replace multiple discrete timing components in space-constrained, cost-sensitive embedded systems while delivering high-frequency flexibility and low jitter.

FAQ

What is the maximum number of unique frequencies above 112.5 MHz that SI5351A-B06486-GTR can generate simultaneously?

The SI5351A-B06486-GTR supports only two unique frequencies above 112.5 MHz at the same time - for example, 125 MHz on CLK0 and 130 MHz on CLK1. Additional outputs above 112.5 MHz must duplicate one of those two frequencies (e.g., CLK2 and CLK3 also at 125 MHz). This limitation arises from internal PLL bandwidth and MultiSynth divider resolution constraints documented in Skyworks Rev. 1.3 datasheet Table 7.

Does SI5351A-B06486-GTR support HCSL-compatible output swing?

Yes, SI5351A-B06486-GTR supports HCSL-compatible output swing through programmable drive strength and termination control. When configured with 50 Ω output impedance and appropriate VDDO (e.g., 1.8 V), its output meets HCSL voltage thresholds (V_OH ≥ 0.75 V, V_OL ≤ 0.25 V) and edge rate requirements per Skyworks Application Note AN551 and datasheet Section 4.3.

Can SI5351A-B06486-GTR operate from a 2.5 V core supply and 1.8 V output supplies simultaneously?

Yes, SI5351A-B06486-GTR supports independent supply rails: VDD may be set to 2.5 V (2.25–2.75 V range), while VDDOA–VDDOD can each be independently biased at 1.8 V (1.71–1.89 V range). This allows direct interfacing with 1.8 V FPGAs or processors without level shifters, as confirmed in Table 3 (Recommended Operating Conditions) of the Skyworks datasheet.

Is external load capacitance required when using a 10 pF crystal with SI5351A-B06486-GTR?

No external load capacitance is required for a 10 pF crystal: SI5351A-B06486-GTR includes programmable internal load capacitance (0/6/8/10 pF) selectable via register 183 bits 7:6. A 10 pF crystal connects directly to XA/XB with internal 10 pF loading enabled, eliminating external capacitors and simplifying layout - per Skyworks AN551 and datasheet Section 4.1.1.

What is the typical power-up time for SI5351A-B06486-GTR to deliver valid clock outputs?

The typical power-up time for SI5351A-B06486-GTR is 2 ms (maximum 10 ms) from VDD reaching VDD_min to stable output clocks, measured with CL = 5 pF and f_CLKn > 1 MHz. In PLL bypass mode - used for crystal oscillator emulation - startup time reduces to 0.5 ms (max 1 ms), as specified in Table 5 (AC Characteristics) of the Skyworks datasheet.