Skyworks Solutions Inc. SI5338B-B08686-GMR

Overview

SI5338B-B08686-GMR from Skyworks Solutions is an I²C-programmable quad clock generator with four independently configurable differential or single-ended outputs, 0.7 ps RMS typical phase jitter, PCIe Gen 1–4 Common Clock and Gen 3 SRNS compliance, and operation across –40 to +85 °C in a 4 × 4 mm 24-QFN package. It replaces up to four crystal oscillators in high-speed serial interface timing applications.

For engineers reviewing the SI5338B-B08686-GMR datasheet, SI5338B-B08686-GMR pinout, SI5338B-B08686-GMR application, or SI5338B-B08686-GMR equivalent, key selection criteria include PCIe Gen 4 jitter compliance (0.15–0.45 ps RMS), independent output voltage per driver (1.5/1.8/2.5/3.3 V), MultiSynth™ fractional synthesis resolution (1 ppb), spread-spectrum control (0.5–5.0% spread, 33–63 kHz modulation), and loss-of-lock/loss-of-signal alarm support.

Technical Context

The SI5338B-B08686-GMR implements a two-stage PLL architecture: a high-stability reference stage (input frequency 5–710 MHz) followed by four independent MultiSynth™ synthesis blocks, each supporting integer or fractional-N division with programmable initial phase offset (±45 ns) and glitchless frequency increment/decrement (1 ppm steps). All outputs are fully decoupled in frequency, format, and voltage.

It supports flexible input references-including external crystals (8–30 MHz), CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), and differential clocks (5–710 MHz)-and delivers output frequencies from 0.16 MHz to 710 MHz across LVPECL, LVDS, HCSL, CML, CMOS, SSTL, and HSTL formats, with independent output supply rails (VDDO0–VDDO3).

Key Specifications

Pinout & Package

SI5338B-B08686-GMR uses a 24-lead QFN package (4 × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments follow standard Si5338 top-view layout: IN1/IN2 (differential ref 1), IN3/IN4 (single-ended ref), IN5/IN6 (differential ref 2/3), CLK0A–CLK3B (four differential output pairs), VDD (core supply), VDDO0–VDDO3 (independent output supplies), SCL/SDA/INTR (I²C interface and interrupt), and GND/RSVD_GND.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5332A-D08686-GM, SI5338B-B08686-GMR offers field-programmability and broader input reference support but higher jitter; compared with ICS853S02IAGLF, it provides full I²C configurability and PCIe Gen 4 compliance at the cost of higher design complexity and bill-of-materials count.

Availability

SI5338B-B08686-GMR is available at Aetrix Electronics and suitable for PCIe Gen 4 switch timing, Ethernet switching/routing, broadcast video timing, and FPGA/processor clocking requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for SI5338B-B08686-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 Si5338 product line delivers programmable, low-jitter clock generation for high-speed serial interfaces including PCIe, Ethernet, Fibre Channel, and broadcast video, emphasizing flexibility, precision, and system-level timing integrity.

FAQ

What is the primary function of the SI5338B-B08686-GMR in a PCIe Gen 4 system?

The SI5338B-B08686-GMR serves as a quad-output clock generator delivering four independent, low-jitter (≤0.45 ps RMS) reference clocks compliant with PCIe Gen 4 Common Clock specifications. It replaces multiple discrete oscillators, supports HCSL output format at 100 MHz, and enables per-output spread-spectrum control to reduce EMI in high-density switch cards.

Does the SI5338B-B08686-GMR support crystal-less operation?

Yes, the SI5338B-B08686-GMR supports crystal-less operation via external clock inputs: CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), or differential (5–710 MHz). It also supports 8–30 MHz external crystals, but does not integrate an oscillator circuit - an external crystal must be used if no system clock is available.

How many independent output voltage supplies does the SI5338B-B08686-GMR support?

The SI5338B-B08686-GMR supports four independent output buffer supply rails - VDDO0, VDDO1, VDDO2, and VDDO3 - each configurable for 1.5 V, 1.8 V, 2.5 V, or 3.3 V. This allows simultaneous generation of mixed-voltage clocks (e.g., 1.8 V LVDS for FPGA I/O and 3.3 V CMOS for legacy peripherals) without external level shifters.

Can the SI5338B-B08686-GMR generate frequencies above 350 MHz on all four outputs simultaneously?

No. The SI5338B-B08686-GMR can generate frequencies above 350 MHz (up to 710 MHz) on only two unique outputs simultaneously - specifically Fvco/4 and Fvco/6 - due to VCO frequency constraints. Other outputs are limited to ≤350 MHz in that configuration, as confirmed in Table 6 Note 6 of the datasheet.

What software tools are officially supported for configuring the SI5338B-B08686-GMR?

Skyworks' ClockBuilder Pro software is the officially supported configuration tool for the SI5338B-B08686-GMR. It enables GUI-based frequency planning, register setup, jitter analysis, and I²C programming. Configuration files generated by ClockBuilder Pro can be deployed directly to the device via its SMBus-compatible interface.