SI52208-A02AGMR - 8-Output PCIe Gen 1-4 Clock Generator | Skyworks
MPN: SI52208-A02AGMR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.45 | $6.45 |
| 10 | $5.8 | $58.00 |
| 100 | $5.18 | $518.00 |
| 500 | $4.65 | $2,325.00 |
| 1,000 | $4.12 | $4,120.00 |
SI52208-A02AGMR Overview
A PCI Express clock generator is a dedicated timing IC that synthesizes the low-jitter reference clocks required by PCIe root complexes, endpoints, switches, and retimers. It belongs to the broader category of clock generators and timing ICs within the timing-and-signal-conditioning block of a computing platform, and is typically placed adjacent to the PCIe PHY or switch to minimize trace-induced jitter.
Key features include a 1.5 V to 1.8 V supply range, low power consumption, hardware pin and I2C programmability for output enable and spread spectrum, and integrated 85 ohm source termination that eliminates external resistors on each differential output pair. Compliance with PCIe Gen 1/2/3/4 phase jitter and SRIS reference-clock architectures allows direct deployment in SRNS and SRIS systems without additional PLL stages.
Typical applications include desktop and server PCIe slot clocking, NVMe SSD controllers, PCIe switch reference-clock trees, riser cards, and embedded-computing PCIe endpoints. The wide frequency support (100/133/200 MHz) covers Gen 1/2 (100 MHz) and Gen 3/4 (100 MHz with optional spread) plus a 25 MHz LVCMOS reference path for downstream clocking.
When designing with this device, follow Skyworks reference-layout guidance for the 48-QFN exposed pad to achieve the published jitter and supply-noise performance. Decouple VDD with 0.1 microfarad plus bulk ceramic caps placed within 2 mm of the pins, and route differential pairs to maintain 100 ohm differential impedance with matched length within 5 mils.
This page synthesizes distributor stock, drop-in Skyworks and Silicon Labs family alternatives, and PCIe-specific design notes that complement the manufacturer datasheet.
Drop-in alternatives for SI52208-A02AGMR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with SI52208-A02AGMR (same form factor and footprint) — differing in Control Interface, Operating Temperature, Output Type, PCIe Compliance, Package.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI52208-A01AGM
✅ Drop-In✓ In Stock
$4.1 / Unit
View Datasheet →SI52212-A01AGM
✅ Drop-In📋 Reference alternative (not in catalog)
SI52204-A02AGM
✅ Drop-In📋 Reference alternative (not in catalog)
SI52202-A02AGM
✅ Drop-In📋 Reference alternative (not in catalog)
SI52208-A02AGMR Specifications
| Function | PCIe Gen 1/2/3/4 clock generator |
| Number of Outputs | 8 differential HCSL outputs |
| Output Frequencies | 100 MHz / 133 MHz / 200 MHz (selectable) |
| Reference Input | 25 MHz LVCMOS |
| Output Type | Differential HCSL with integrated 85 ohm termination |
| Supply Voltage | 1.5 V to 1.8 V |
| PCIe Compliance | Gen 1 / Gen 2 / Gen 3 / Gen 4 + SRIS |
| Control Interface | Hardware pins and I2C |
| Spread Spectrum | Hardware and I2C enable/disable |
| Individual Output Enable | Yes (one pin per output) |
| Package | 48-pin QFN (6 x 6 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Operating Temperature | -40 C to +85 C (industrial) |
| RoHS Status | Compliant |
SI52208-A02AGMR Pin Configuration
| Pin 1 | VDD — Core supply, 1.5-1.8 V |
| Pin 2 | GND — Ground |
| Pin 3 | XIN/REF — 25 MHz LVCMOS reference input |
| Pin 4 | XOUT — Reference output (crystal mode) |
| Pin 5 | SDA — I2C data |
| Pin 6 | SCL — I2C clock |
| Pin 7 | OE0 — Output 0 enable, active high |
| Pin 8 | OE1 — Output 1 enable, active high |
| Pin 9 | OE2 — Output 2 enable, active high |
| Pin 10 | OE3 — Output 3 enable, active high |
| Pin 11 | OE4 — Output 4 enable, active high |
| Pin 12 | OE5 — Output 5 enable, active high |
| Pin 13 | OE6 — Output 6 enable, active high |
| Pin 14 | OE7 — Output 7 enable, active high |
| Pin 15 | F_SEL0 — Frequency select 0 |
| Pin 16 | F_SEL1 — Frequency select 1 |
| Pin 17 | SS_EN — Spread-spectrum enable |
| Pin 18 | SRIS_EN — SRIS mode enable |
| Pin 19 | OUT0_P — Differential output 0 positive (HCSL) |
| Pin 20 | OUT0_N — Differential output 0 negative (HCSL) |
| Pin 21 | OUT1_P — Differential output 1 positive |
| Pin 22 | OUT1_N — Differential output 1 negative |
| Pin 23 | VDD — Output supply |
| Pin 24 | GND — Ground |
| Pin 25 | OUT2_P — Differential output 2 positive |
| Pin 26 | OUT2_N — Differential output 2 negative |
| Pin 27 | OUT3_P — Differential output 3 positive |
| Pin 28 | OUT3_N — Differential output 3 negative |
| Pin 29 | OUT4_P — Differential output 4 positive |
| Pin 30 | OUT4_N — Differential output 4 negative |
| Pin 31 | OUT5_P — Differential output 5 positive |
| Pin 32 | OUT5_N — Differential output 5 negative |
| Pin 33 | VDD — Output supply |
| Pin 34 | GND — Ground |
| Pin 35 | OUT6_P — Differential output 6 positive |
| Pin 36 | OUT6_N — Differential output 6 negative |
| Pin 37 | OUT7_P — Differential output 7 positive |
| Pin 38 | OUT7_N — Differential output 7 negative |
| Pin 39 | VDD — Output supply |
| Pin 40 | GND — Ground |
| Pin 41 | NC — Not connected (per datasheet) |
| Pin 42 | NC — Not connected (per datasheet) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | NC — Not connected (per datasheet) |
| Pin 45 | NC — Not connected (per datasheet) |
| Pin 46 | NC — Not connected (per datasheet) |
| Pin 47 | NC — Not connected (per datasheet) |
| Pin 48 | NC — Not connected (per datasheet) |
Typical Applications
SI52208-A02AGMR is suitable for 6 applications: Desktop and Workstation PCIe Slot Clocking, Server PCIe Reference-Clock Tree, NVMe SSD Controller Reference Clock, PCIe Switch Fanout, Embedded Computing PCIe Endpoints, Riser Card and Add-In Card Clocking.
Desktop and Workstation PCIe Slot Clocking
The SI52208-A02AGMR delivers eight 100 MHz HCSL clocks from one 48-QFN device, directly driving the PCIe reference-clock pins of root-complex chipsets and downstream slots. Its 4.0 ps RMS phase jitter at Gen 4 holds margin against the PCIe Gen 4 jitter budget of 1.5 ps RMS, and the integrated 85 ohm source termination removes external series resistors for cleaner SI on riser cards.
Recommended
Server PCIe Reference-Clock Tree
In 1U/2U servers, the SI52208-A02AGMR's eight outputs feed CPU PCIe lanes, BMC, and riser slots from a single timing IC. Hardware output-enable pins and I2C control support per-slot power-down during low-power states, and the 1.5-1.8 V supply matches the platform's standby rail, avoiding an extra LDO. SRIS support enables modern CPU architectures with separate reference clock domains.
Recommended
NVMe SSD Controller Reference Clock
NVMe Gen 3 and Gen 4 SSDs need a clean 100 MHz HCSL reference with tight additive jitter to keep the PCIe eye open over long M.2 traces. The SI52208-A02AGMR provides that with sub-1 ps RMS additive jitter per the Si522xx datasheet, and its small 6x6 mm QFN footprint fits M.2 2230/2280 SSD board layouts. A single 25 MHz crystal feeds the reference input, minimizing BOM cost.
Recommended
PCIe Switch Fanout
A PCIe switch such as the PI7C9X111 requires multiple 100 MHz reference clocks to feed its downstream ports. The SI52208-A02AGMR can source all eight downstream HCSL pairs from one IC, simplifying the clock tree and reducing BOM. Hardware OE pins allow unused ports to be disabled for power savings when ports are not populated.
Recommended
Embedded Computing PCIe Endpoints
Industrial single-board computers and COM-HPC modules often expose multiple PCIe lanes for GPUs, FPGAs, or NICs. The SI52208-A02AGMR's industrial temperature range (-40 to +85 C) and Gen 4 jitter compliance make it a robust reference-clock source for these systems. Spread-spectrum capability reduces EMI for CE/FCC compliance in compact enclosures.
Recommended
Riser Card and Add-In Card Clocking
Add-in cards such as NICs, RAID controllers, and GPUs often need a PCIe reference clock when operating in non-transparent or dual-root configurations. The SI52208-A02AGMR's small footprint and integrated 85 ohm termination simplify the BOM on a constrained PCB, while hardware OE pins let the host turn off the add-in card's clock in standby. The 1.5-1.8 V supply matches auxiliary rails on most add-in cards.
Recommended
Recommended Products Summary
Engineering reference data for SI52208-A02AGMR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI52208-A01AGM | SI52212-A01AGM | SI52204-A02AGM | SI52202-A02AGM |
|---|---|---|---|---|---|
| Brand | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions |
| Package | 48-QFN (6x6 mm) | 48-QFN (6x6 mm) - same | 48-QFN (6x6 mm) - same | 48-QFN (6x6 mm) - same | 48-QFN (6x6 mm) - same |
| Number of Outputs | 8 | 8 | 12 (+50%) | 4 (-50%) | 2 (-75%) |
| PCIe Generation | Gen 1/2/3/4 + SRIS | Gen 1/2/3 | Gen 1/2/3 | Gen 1/2/3/4 + SRIS | Gen 1/2/3/4 + SRIS |
| Output Frequencies | 100/133/200 MHz | 100/133/200 MHz | 100/133/200 MHz | 100/133/200 MHz | 100/133/200 MHz |
| Supply Voltage | 1.5-1.8 V | 1.5-1.8 V | 1.5-1.8 V | 1.5-1.8 V | 1.5-1.8 V |
| Reference Input | 25 MHz LVCMOS | 25 MHz LVCMOS | 25 MHz LVCMOS | 25 MHz LVCMOS | 25 MHz LVCMOS |
| Individual Output Enable | Yes | Yes | Yes | Yes | Yes |
| Control Interface | Hardware pins + I2C | Hardware pins + I2C | Hardware pins + I2C | Hardware pins + I2C | Hardware pins + I2C |
Key Differentiators
- Integrated 85 ohm source termination eliminates external HCSL resistors (vs Discrete HCSL clock generators without integrated termination)
- PCIe Gen 4 + SRIS compliance in the same 48-QFN family (vs A01 order code in same family)
- 8 outputs from a single 6x6 mm QFN (vs SI52204-A02AGM with 4 outputs)
Design Notes
Place the SI52208-A02AGMR as close as possible to the PCIe root-complex or switch reference-clock input pins to minimize trace-induced jitter. Each HCSL differential pair should be routed as 100 ohm differential with intra-pair length matching within 5 mils. The exposed pad must be soldered to a continuous ground plane with thermal vias for heat dissipation and return-current continuity.
Decouple each VDD pin with a 0.1 microfarat X7R ceramic capacitor placed within 2 mm of the pin, plus a 1 microfarad bulk capacitor. The SI52208-A02AGMR is sensitive to supply noise on the 1.5-1.8 V rail; for low-jitter PCIe Gen 3/4 operation, derive this rail from a low-noise LDO rather than the main switching converter output.
Do not enable spread spectrum simultaneously on both upstream and downstream devices, as cascaded spread can exceed the PCIe jitter budget. Verify the F_SEL0/F_SEL1 pins match the platform's required frequency at every power-up, since I2C register changes can be lost if the optional non-volatile memory is not used. Refer to the Skyworks Si522xx datasheet register map section for OE pin polarity and SRIS_EN behavior at startup.
Compliance Information
RoHS and REACH compliance per Skyworks product page. Not AEC-Q100 qualified - this part targets commercial/industrial PCIe platforms, not automotive. Halogen-free status not stated in available data and set to 'unknown'.
