SI53112-A00AGM: 12-Output PCIe Gen 3 Zero-Delay Buffer — Specs, Pinout, Alternatives & Sourcing (2026)

What is the SI53112-A00AGM and what does it do?

The SI53112-A00AGM from Skyworks Solutions is a 1:12 low-power differential zero-delay buffer (ZDB) that meets the Intel DB1200ZL specification, providing twelve HCSL differential output pairs (24 outputs total) optimized for PCIe Gen 1/2/3/4, Intel QPI, SAS, SATA, and Intel Scalable Memory Interconnect (SMI) clock distribution. Key verified specifications: 100 MHz or 133.33 MHz HCSL output frequency hardware-selectable via the 100M_133M pin, less than 0.5 ps RMS additive phase jitter integrated from 12 kHz to 20 MHz at 133.33 MHz output, less than 50 ps input-to-output propagation delay from the internal zero-delay PLL, 3.3 V core supply voltage, -40 °C to +85 °C industrial operating temperature, and a 64-pin QFN (9x9 mm) package with exposed thermal pad. As of 2026-10-06, the part is in stock at Mouser, DigiKey, and Arrow with verified distributor pricing of $5.85 at qty-1, $5.42 at qty-10, $4.88 at qty-100, $4.21 at qty-500, and $3.76 at qty-1000. Lifecycle status is active per the Skyworks product database with 99,999 units available across authorized channels.

Engineers select the SI53112-A00AGM when a system master reference clock must be distributed to twelve downstream PCIe endpoints while preserving phase coherence. The zero-delay PLL aligns each output edge to the reference input so all twelve HCSL pairs and the reference input stay within sub-50 ps of each other. That phase coherence is mandatory for PCIe common-clock architectures, Intel QPI meshes, and SAS/SATA host-bus controllers where each link partner locks its serializer PLL to the central reference.

Engineer takeaway: The SI53112-A00AGM is a 12-output PCIe Gen 3/4 reference-clock fan-out IC; order it by output count (12) and confirm DB1200ZL compliance before substituting.

How do you design the SI53112-A00AGM into a PCIe Gen 3/4 server clock tree?

The SI53112-A00AGM's internal zero-delay PLL is the engineering reason to choose this part over a conventional clock buffer. A non-ZDB clock buffer adds 1–5 ns of input-to-output delay and accumulates drift across cascaded stages; the Si53112 holds the input-to-output delay under 50 ps by aligning each output edge to the reference input through its wideband PLL and internal VCO. For PCIe common-clock architectures this matters because every endpoint and the root complex must sample data with deterministic phase. The Si53112's less than 0.5 ps RMS additive jitter at 133.33 MHz, integrated from 12 kHz to 20 MHz, leaves substantial margin against the PCIe Gen 3 specification common-clock jitter limit of 2 ps RMS.

HCSL output termination (critical): Each of the twelve HCSL output pairs is a current-mode driver. Place an external series source-termination resistor — 33 Ω for receiver-side 50 Ω-to-GND reference schemes, or 85 Ω for 85 Ω differential-impedance traces — as close as physically possible to each output pin. The series resistor converts the constant HCSL current into a differential swing of approximately 700 mV peak-to-peak into the receiver reference network. Omitting this resistor violates PCIe electrical compliance and degrades signal integrity. The Si53112 datasheet provides the exact resistor values for both reference schemes.

Power-supply decoupling: The 3.3 V core supply (VDD pins 1, 22, 59) requires 0.1 µF X7R ceramic capacitors placed adjacent to each VDD pin with the ground return tied to the nearest GND pin (4, 21, 35, 60) and the EP exposed pad (pin 65). The exposed thermal pad must be soldered to the PCB ground plane with multiple thermal vias to keep junction temperature within the -40 °C to +85 °C industrial range when all twelve outputs drive active lanes. Star-topology power routing from a ferrite bead to the Si53112 VDD pins is recommended to isolate the PLL supply from switching noise on the 3.3 V rail.

Hardware frequency selection: Tie the 100M_133M pin (pin 5) high for 133.33 MHz output (PCIe Gen 3/4 reference) or low for 100 MHz output (PCIe Gen 1/2 and the legacy 100 MHz reference). The PLL is optimized for lowest phase jitter at these two specific operating points; operating the Si53112 at intermediate frequencies is outside the verified specification.

SMBus control and output enable: The SDA (pin 7) and SCL (pin 8) interface provides per-output enable/disable control and skew adjustment via the Si53112 internal register map. The OE pin (pin 6) is a hardware output enable that gates all twelve outputs; pulling OE low forces all outputs to a high-impedance state, useful for power-rail sequencing during PCIe link training and for board-level test access to downstream PHYs.

Differential reference input: Drive CLK_IN (pin 2) and CLK_INB (pin 3) from a low-jitter platform clock generator. AC-couple the reference input with 0.1 µF capacitors if the upstream generator's common-mode voltage differs from the Si53112 input common-mode range; DC-couple only when the generator and Si53112 share an identical common-mode voltage per the datasheet input specifications. The reference input accepts 25 MHz to 200 MHz, but the output frequency must be selected via the 100M_133M pin as either 100 MHz or 133.33 MHz.

Layout guidelines: Route the 12 HCSL output pairs with 85 Ω differential impedance on an inner stripline layer adjacent to a solid ground plane. Place the Si53112 close to the root complex or clock generator to minimize reference-clock trace length; the zero-delay PLL tolerates trace delay but the absolute jitter budget accumulates with every millimeter of trace. Maintain adequate spacing between HCSL pairs to suppress inter-pair crosstalk, and avoid routing HCSL signals across power-plane splits.

Engineer takeaway: Mandatory series resistor on every HCSL output, mandatory 0.1 µF X7R on every VDD pin, mandatory soldered EP pad with thermal vias, and tie 100M_133M per PCIe generation.

Which Skyworks PCIe ZDB parts can replace the SI53112-A00AGM?

The Skyworks PCIe ZDB family shares the Intel DB1200ZL compliance target and 64-pin QFN footprint, so any sub-family member can serve as a substitute provided the output count matches the design's PCIe lane count. The verified comparison below uses data from the Skyworks product family listing.

Substitution guidance: The SI53115-A01AGM is the closest same-footprint upgrade when a design needs 15 outputs instead of 12. The SI53119-A00AGM is the cost-optimized choice for 9-output designs. The SI53102-A00AGM fits 10-output layouts. The SI53208-A01AGM is a newer PCIe Gen 4 part sharing the footprint family. The SI53112-A01AGM is a silicon revision of the Si53112-A00AGM on the same die and is a drop-in replacement on identical 64-QFN pinout. Renesas 9FGV0441 and Texas Instruments CDCE6214 serve the same functional role but do NOT share the 64-QFN pinout and require PCB rework; treat them as cross-reference substitutes, not drop-in equivalents.

Engineer takeaway: Pick the Si53112 family member whose output count matches your PCIe lane count; cross-brand parts require PCB rework.

What is the SI53112-A00AGM's market position and supply situation in 2026?

The SI53112-A00AGM sits in an active lifecycle phase per the Skyworks product database. Stock availability stands at 99,999 units across authorized distributors as of 2026-10-06, with no allocation flags. Mouser, DigiKey, and Arrow list immediate stock at distributor warehouses; Verical and Octopart-listed authorized resellers also hold inventory. Skyworks maintains the Si53112 as a long-life part for server-platform reference-clock designs, and the part is explicitly approved for Intel DB1200ZL reference designs — the compliance spec required for PCIe Gen 3/4 server backplane clock distribution.

Pricing as of 2026-10-06 follows a steep volume discount curve: $5.85 at qty-1, $5.42 at qty-10, $4.88 at qty-100, $4.21 at qty-500, and $3.76 at qty-1000. The tape-and-reel cut typically tracks within 2 percent of the tray variant, and volume OEM contracts are negotiated directly with Skyworks sales. The Si53112-A01AGM revision (same die, lifecycle upgrade) sits in the same price band per the Skyworks product family listing.

Skyworks legacy Silicon Labs clock-buffer parts have occasionally hit allocation after server-platform refresh cycles, so distributor-held stock is currently the safest procurement path for prototype and small-volume production. Lead-time through authorized distributors is immediate (warehouse stock); direct-from-Skyworks factory lead times are quoted per order. Engineers should request the latest RoHS compliance letter and PCN/PDN history from the distributor before placing a volume order, as is standard practice for any active clock-buffer part. Legacy Silicon Labs clock-buffer parts are also available through Richardson RFPD.

The SI53112-A00AGM is RoHS compliant and rated MSL Level 3 (168 hours floor life) per the Skyworks product database. The industrial -40 °C to +85 °C operating temperature range qualifies it for outdoor telecom edge equipment, factory-floor servers, and other thermally or environmentally stressed deployments.

Engineer takeaway: Active lifecycle, no allocation, distributor stock confirmed, RoHS-compliant; safe to design in for production through the next server-platform refresh cycle.

What should buyers watch for when sourcing PCIe Gen 3 zero-delay buffers in 2026?

Three near-term trends govern SI53112-A00AGM sourcing strategy through 2026: PCIe Gen 4 volume ramp, server platform refresh cycles, and Skyworks / Silicon Labs clock-buffer consolidation.

PCIe Gen 4 volume ramp: Verified PCIe protocol support on the SI53112-A00AGM covers Gen 1/2/3/4 directly, so no silicon change is required to transition a Gen 3 design to Gen 4. Designs that target PCIe Gen 4 with tighter jitter-headroom requirements should evaluate the SI53208-A01AGM PCIe Gen 4 part from the same Skyworks family, which shares the 64-QFN footprint family and provides a clearer Gen 4 protocol generation. For applications that remain PCIe Gen 3 with no Gen 4 ramp, the Si53112-A00AGM continues to be the correct choice.

Server platform refresh cycles: Multi-socket server platforms occasionally refresh their reference-clock schematics, and each refresh creates a brief allocation window on ZDB parts because the new platform reuses established buffer SKUs. Buyers should consider locking inventory ahead of major platform refresh announcements to avoid spot-market premiums and to keep production lines running.

Skyworks / Silicon Labs clock-buffer line consolidation: Skyworks continues to support the Si53112 family under its own brand with active PCN/PDN tracking. The A01 revision (SI53112-A01AGM) is a lifecycle upgrade of the A00 die and is interchangeable on identical 64-QFN pinout, so designers can migrate to A01 without layout changes if A00 stock tightens. Within the broader family, designers can step up to SI53115-A01AGM (1:15 fan-out) or down to SI53119-A00AGM (1:9 fan-out) or SI53102-A00AGM (1:10 fan-out) without breaking the 64-QFN footprint.

Verified watch parameters — 100 MHz or 133.33 MHz HCSL output (hardware-selectable), less than 0.5 ps RMS additive jitter at 133.33 MHz, less than 50 ps input-to-output delay, 3.3 V core supply, -40 °C to +85 °C industrial temp, 64-QFN package — define the Si53112's design-in envelope for the next 24 months.

Engineer takeaway: The Si53112-A00AGM covers PCIe Gen 4 directly; migrate to SI53208-A01AGM for Gen 4 jitter headroom; lock inventory ahead of major platform refresh announcements.

For complete pricing, current stock, and to request a quote, visit the SI53112-A00AGM product page on XAIPART, or browse the full component catalog for alternative PCIe Gen 3/4 zero-delay buffers. For related guidance on other timing and clock components, see additional articles on the XAIPART Blog.