Skyworks Solutions Inc. SI5338B-B03800-GMR

Overview

SI5338B-B03800-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 and SRNS compliance, and MultiSynth™ frequency synthesis supporting 0.16–710 MHz output ranges. It replaces up to four crystal oscillators in FPGA, processor, and Ethernet switch timing systems.

For engineers reviewing the SI5338B-B03800-GMR datasheet, SI5338B-B03800-GMR pinout, SI5338B-B03800-GMR application, or SI5338B-B03800-GMR equivalent, key selection criteria include its 24-QFN package, independent per-output voltage (1.5/1.8/2.5/3.3 V), spread-spectrum capability (0.5–5.0% down-spread), glitchless 1 ppm frequency adjustment, and <20 ps phase step resolution.

Technical Context

The SI5338B-B03800-GMR implements a two-stage PLL architecture: a high-stability reference stage (with crystal or external clock input) feeding a fractional-N MultiSynth™ synthesis stage per output. Each of the four outputs uses dedicated M/N/R dividers and supports integer or fractional mode operation with programmable initial phase offset (±45 ns) and real-time phase/frequency increment/decrement control.

It accepts six input sources (IN1–IN6): differential (5–710 MHz), CMOS (5–200 MHz), SSTL/HSTL (5–350 MHz), or 8–30 MHz crystal. Output drivers support LVPECL/LVDS/HCSL/CMOS/SSTL/HSTL formats with independent VDDO supplies and configurable slew rates, enabling direct interface to FPGAs, ASICs, and SerDes PHYs without level-shifting components.

Key Specifications

Pinout & Package

SI5338B-B03800-GMR is housed in a 24-lead QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad. Pin assignments are fixed per the Si5338 family and validated for this variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with Si5338A-B03800-GM, the SI5338B-B03800-GMR provides identical hardware functionality but with distinct factory OTP settings; compared with LMK04832, it delivers PCIe Gen 4 compliance at half the power and 50% smaller footprint-making it optimal for space-constrained, cost-sensitive embedded and networking platforms.

Availability

SI5338B-B03800-GMR is available at Aetrix Electronics and suitable for Ethernet switch/router design, PCIe Gen 4 server platforms, and broadcast video timing applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for SI5338B-B03800-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, with leadership in RF, timing, and power management ICs for infrastructure, automotive, and mobile markets.

The Si5338 product line was designed specifically for high-density, multi-protocol timing consolidation in networking, computing, and communications equipment-enabling replacement of multiple discrete oscillators with a single programmable device.

FAQ

What is the default configuration of the SI5338B-B03800-GMR at power-up?

The SI5338B-B03800-GMR powers up with factory-programmed OTP settings that configure it as a quad-output clock generator with specific default frequencies, output formats, and voltage levels. These settings are non-volatile and persist without I²C programming. Full customization requires ClockBuilder Pro software and I²C initialization to overwrite the default NVM configuration.

Does the SI5338B-B03800-GMR support PCIe Gen 4 Separate Reference No Spread (SRNS) mode?

Yes, the SI5338B-B03800-GMR supports PCIe Gen 4 SRNS mode with 0.11–0.32 ps RMS jitter (10 kHz–50 MHz) when configured with a PLL bandwidth of 2–4 MHz and CDR set to 10 MHz. This is explicitly validated in Table 12 of the official datasheet and meets PCI-SIG Base Specification 4.0 rev 0.5 requirements.

Can the SI5338B-B03800-GMR generate four different frequencies simultaneously above 350 MHz?

No. The SI5338B-B03800-GMR can output only two unique frequencies above 350 MHz simultaneously-specifically Fvco/4 and Fvco/6-as stated in Note 6 of Table 6. Higher-frequency outputs require integer-related relationships and shared VCO resources; full independence is limited to frequencies ≤350 MHz.

How is spread spectrum applied on the SI5338B-B03800-GMR, and can it be enabled per output?

Spread spectrum is configurable independently on any of the four outputs of the SI5338B-B03800-GMR, with selectable parameters: frequency range (5–350 MHz), spread magnitude (0.5–5.0%), and modulation rate (33–63 kHz). It is implemented digitally within the MultiSynth™ engine and does not require external components or analog modulation circuitry.

What is the maximum allowable input slew rate for low-jitter operation of the SI5338B-B03800-GMR?

For optimal jitter performance, the SI5338B-B03800-GMR requires differential input slew rates >0.3 V/ns (measured at mid-point) on IN1/IN2/IN5/IN6, and single-ended input slew rates >1.0 V/ns on IN3/IN4. Exceeding these thresholds ensures deterministic edge detection and minimizes jitter contribution from input signal integrity degradation.