PI6C557-03AQE - PCIe 2.0 Spread Spectrum Clock Generator | Diodes Inc
N.º de pieza: PI6C557-03AQE ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $1.42 | $1,42 |
| 10 | $1.28 | $12,80 |
| 100 | $1.04 | $104,00 |
| 500 | $0.86 | $430,00 |
| 1.000 | $0.74 | $740,00 |
PI6C557-03AQE Descripción general
A spread-spectrum clock generator is a timing device that intentionally modulates the output frequency around a center value at a low modulation rate. By spreading the spectral energy of the clock over a wider bandwidth, peak EMI emissions are reduced, helping designs pass regulatory compliance tests such as FCC Class B and CISPR 22. Within the broader clock-and-timing IC category, this part sits in the PCIe clock-generator subcategory alongside PLLs, frequency synthesizers, and zero-delay buffers.
Key features include a 25 MHz crystal input, two HCSL (current-mode differential) output pairs, on-chip termination support, output enable / power-down control, and selectable spread-spectrum depth. HCSL is the signaling standard required by PCIe 2.0/3.0 reference clocks and is also used in mainstream Ethernet PHYs. The internal PLL is sourced from Pericom's spread-spectrum technology and maintains low cycle-to-cycle jitter even with active modulation.
Typical applications include PCIe add-in cards (network, storage, graphics), embedded systems needing EMI-controlled 100 MHz reference clocks, Ethernet switches and NIC reference rails, and industrial PCs where the part's compliance footprint helps shorten EMI qualification cycles. The device's small 16-QSOP footprint is suitable for compact motherboard layouts.
When designing with the PI6C557-03AQE, follow PCIe CEM routing guidelines for the HCSL outputs - 85 ohm differential traces, AC coupling capacitors at the receiver, and length matching within the PCIe spec. The 25 MHz crystal must be fundamental-mode with a load capacitance appropriate for the on-chip oscillator.
Alternativas directas para PI6C557-03AQE — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con PI6C557-03AQE (mismo factor de forma y huella) — difiere en Number of Outputs, Package, Function, Output Type, Number of Inputs.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
PI6C557-03AQEX
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PI6C557-03ALEX
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PI6C557-03BLE
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
PI6C557-03AQE Valores máximos y características eléctricas
| Product Type | Spread-Spectrum Clock Generator |
| Función | PCI Express / Ethernet reference clock generator |
| Input Reference | 25 MHz fundamental-mode crystal |
| Output Frequency Options | 25 / 100 / 125 / 200 MHz (selectable) |
| Número de salidas | 2 differential pairs (4 signals) |
| Tipo de salida | HCSL (current-mode differential) |
| Tensión de alimentación | 3.3 V (3.0 V to 3.6 V range) |
| PCIe Compliance | PCI Express 2.0 reference clock |
| Spread Spectrum | Selectable spread depth |
| Temperatura de funcionamiento | -40 C to +85 C (industrial) |
| Encapsulado | 16-QSOP (also listed as 16-SSOP) |
Configuración de pines de PI6C557-03AQE
| Pin 1 | VDD — 3.3 V power supply |
| Pin 2 | GND — Ground reference |
| Pin 3 | X1 — 25 MHz crystal input 1 |
| Pin 4 | X2 — 25 MHz crystal input 2 |
| Pin 5 | OE — Output enable (active per datasheet) |
| Pin 6 | S0 — Frequency select input 0 |
| Pin 7 | S1 — Frequency select input 1 |
| Pin 8 | GND — Ground reference |
| Pin 9 | Q0 — HCSL output 0 (positive) |
| Pin 10 | Q0# — HCSL output 0 (negative) |
| Pin 11 | VDD — 3.3 V power supply (output) |
| Pin 12 | GND — Ground reference |
| Pin 13 | Q1 — HCSL output 1 (positive) |
| Pin 14 | Q1# — HCSL output 1 (negative) |
| Pin 15 | NC — Not connected (per datasheet) |
| Pin 16 | VDD — 3.3 V power supply |
Aplicaciones típicas
PI6C557-03AQE es adecuado para 6 aplicacións: PCIe Add-in Card Reference Clock, Embedded System Reference Clock, Ethernet Switch / NIC Reference, Storage Controller Clock Tree, Industrial PC Motherboard, Set-Top Box / Consumer Electronics.
PCIe Add-in Card Reference Clock
The PI6C557-03AQE supplies the 100 MHz HCSL reference clock that every PCIe Gen 2 endpoint (NIC, SSD controller, GPU) requires for link training and serializer-deserializer operation. With two HCSL output pairs from one 25 MHz crystal, this Diodes device is ideal for add-in cards that drive both a local endpoint and a downstream slot. Its spread-spectrum modulation reduces conducted and radiated EMI by 7-12 dB on 100 MHz harmonics, easing FCC Class B qualification for consumer NICs and graphics cards. The 16-QSOP footprint fits compact card layouts.
Recomendado
Embedded System Reference Clock
Embedded boards needing an EMI-controlled 100 MHz PCIe reference clock for onboard devices (Ethernet PHY, SATA controller, M.2 slot) benefit from the PI6C557-03AQE's small footprint and spread-spectrum output. The part's 3.3 V supply is compatible with standard industrial SBC rails, and its -40 C to +85 C industrial temperature rating supports factory-floor installations. Pairing it with a 25 MHz crystal oscillator on the same board avoids the need for an external clock generator chip, simplifying BOM and shrinking PCB area in industrial PCs and IoT gateways.
Recomendado
Ethernet Switch / NIC Reference
Gigabit Ethernet PHYs and 10/100/1000 switches commonly require 25 MHz or 125 MHz reference clocks. The PI6C557-03AQE provides both HCSL pairs from a single 25 MHz crystal, with the 125 MHz output suited to many Ethernet PHY reference inputs and the 100 MHz pair serving downstream PCIe devices. Spread-spectrum frequency modulation is particularly valuable in multi-port enterprise switches where FCC/CE compliance at high port densities is challenging. Pin compatibility within the Diodes PI6C557-03A family allows seamless migration across products.
Recomendado
Storage Controller Clock Tree
NVMe SSDs, SAS/SATA controllers, and RAID HBAs each require a clean 100 MHz PCIe reference clock. The PI6C557-03AQE with its two HCSL pairs can feed both a host PCIe Gen 2 endpoint PHY and a downstream port expander, simplifying the storage controller board clock tree. Spread-spectrum modulation helps SSDs in densely packed enterprise arrays pass EMI limits without extensive shielding. The 16-QSOP industrial-grade package supports the wide temperature ranges required by data-center storage enclosures.
Recomendado
Industrial PC Motherboard
Industrial motherboards need a reliable PCIe reference clock for multiple add-in slots while keeping EMI emissions within industrial certification limits (EN 55022, FCC Part 15). The PI6C557-03AQE's two HCSL outputs can fan out to two PCIe Gen 2 slots from a single 25 MHz crystal, and its spread-spectrum output eases the burden on motherboard-level EMI shielding. The 16-QSOP package is compatible with automated SMT assembly lines used in industrial PC production. The same Diodes part serves Fanless industrial designs where thermal and EMI margins are tight.
Recomendado
Set-Top Box / Consumer Electronics
Consumer set-top boxes and HDMI-enabled media gateways integrate Ethernet and PCIe interfaces that require a 100 MHz PCIe reference clock. The PI6C557-03AQE provides two HCSL pairs from a single 25 MHz reference, allowing the same clock source to feed both the Ethernet PHY and the HDMI bridge chip. Spread-spectrum modulation is critical in CE-marked consumer devices, where rigid FCC Class B / EN 55022 limits apply. The small 16-QSOP footprint keeps BOM cost low in cost-sensitive consumer applications.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para PI6C557-03AQE — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | PI6C557-03AQEX | PI6C557-03ALEX | PI6C557-03BLE |
|---|---|---|---|---|
| Brand | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated | Diodes Incorporated |
| Package | 16-QSOP | 16-QSOP - same | 16-QSOP - same | 16-QSOP - same |
| PCIe Generation | PCIe 2.0 | PCIe 2.0 | PCIe 2.0 | PCIe 2.0 |
| Output Frequencies | 25/100/125/200 MHz | 25/100/125/200 MHz | 25/100/125/200 MHz | 25/100/125/200 MHz |
| Output Signaling | HCSL x2 pairs | HCSL x2 pairs | HCSL x2 pairs | HCSL x2 pairs |
| Supply Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Spread Spectrum | Selectable | Selectable | Selectable | Selectable |
| Crystal Reference | 25 MHz fundamental | 25 MHz fundamental | 25 MHz fundamental | 25 MHz fundamental |
Diferenciadores clave
- Pin-to-pin drop-in within the PI6C557-03A family (frente a PI6C557-03AQEX / PI6C557-03ALEX / PI6C557-03BLE)
- Two HCSL differential outputs from one 25 MHz crystal (frente a Single-output clock generators)
- On-chip spread spectrum for EMI reduction (frente a Non-spread-spectrum 100 MHz clock generators)
Notas de diseño
Follow PCI Express CEM routing guidelines for the 100 MHz HCSL outputs: use 85 ohm differential impedance, place AC-coupling capacitors at the receiver (within 200 mils of the receiver pin), and match intra-pair length to within 5 mils. Keep the 25 MHz crystal traces short and symmetric to the X1/X2 pins, with the crystal load capacitors placed within 50 mils. Avoid routing the HCSL outputs across any split-plane or non-continuous reference plane, which increases radiated EMI and can break PCIe link training.
Do not omit the output enable (OE) pull-up/down resistor when unused - if left floating, the HCSL outputs may be in an undefined state and produce unwanted clock activity at power-up, confusing PCIe link training. Select S0/S1 frequency-select inputs via logic-level CMOS signals; they must not be left floating. Verify the 25 MHz crystal's load capacitance rating (typically 18 pF or 20 pF) against the on-chip oscillator specification; mismatch reduces the effective pull range by tens of ppm and may violate PCIe Gen 2 ppm requirements.
Spread-spectrum modulation on the 100 MHz HCSL output typically reduces peak EMI by 7-12 dB depending on spread depth selection. Re-measure conducted and radiated emissions after PCB layout changes; spread depth above -0.5% may exceed the PCIe CEM spec for some receivers and must be validated. Pair the PI6C557-03AQE with a low-ESR decoupling capacitor (0.1 uF X7R) within 100 mils of each VDD pin to minimize supply-borne jitter. If the design is EMC-sensitive (industrial, automotive), consider shielding the clock section and using ferrite beads on the 3.3 V supply rail.
Información de cumplimiento
RoHS compliant per Diodes Inc product family documentation. Industrial temperature grade -40 C to +85 C. Not AEC-Q100 qualified; choose an automotive-grade spread-spectrum clock generator for vehicle applications.
