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Diodes Incorporated PI6C557-03ALE
- Part No.:
- PI6C557-03ALE
- Manufacturer:
- Diodes Incorporated
- Category:
- Application Specific Clock/Timing
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
PI6C557-03ALE.pdf
- Description:
- IC CLOCK GENERATOR 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,197
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Product details
Overview
PI6C557-03ALE from Diodes Incorporated is a PCIe 2.0-compliant spread spectrum clock generator with two HCSL differential outputs, designed for EMI reduction in PC and embedded systems. It accepts a 25MHz crystal input, delivers selectable output frequencies (25/100/125/200MHz), supports -0.5%/-0.75% spread or no spread, and operates at 3.3V ±10% across -40°C to +85°C.
For engineers reviewing the PI6C557-03ALE datasheet, PI6C557-03ALE pinout, PI6C557-03ALE application, or PI6C557-03ALE equivalent, key selection criteria include PCIe 2.0 RMS jitter compliance (≤3.1ps), HCSL output drive capability (0.8V current-mode), external frequency/spread control via S0/S1/SS0/SS1 pins, and TSSOP-16 packaging for high-density board layouts.
Technical Context
The PI6C557-03ALE implements a proprietary Phase-Locked Loop architecture optimized for low-phase-jitter synthesis from a 25MHz fundamental crystal. Its dual-output stage supports independent HCSL termination with precise crossing-point voltage control (250–550mV) and tight skew (<50ps) between CLK0/CLK1 pairs.
Frequency and spread are selected via four dedicated digital control inputs (S0, S1, SS0, SS1), each with internal pull-up resistors-enabling configuration without external logic. The device integrates an IREF pin for precision current reference (2.32mA typical with 475Ω resistor), directly scaling output drive strength (IOH = 6 × IREF).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Type | Dual HCSL differential clock outputs (CLK0/CLK0̅, CLK1/CLK1̅) |
| Input Frequency | 25MHz crystal or single-ended clock - fixed reference for PLL synthesis |
| Output Frequencies | 25MHz, 100MHz, 125MHz, 200MHz - selected by S1:S0 per Table 1 |
| Spread Spectrum | -0.5%, -0.75%, or no spread - selected by SS1:SS0 per Table 2 |
| Phase Jitter (RMS) | 3.1ps @ 100MHz - meets PCIe 2.0 specification for timing integrity |
| Cycle-to-Cycle Jitter | 35ps (typ) - ensures stable edge placement under load variation |
| Supply Voltage | 3.3V ±10% - compatible with standard I/O rail; requires local 0.01μF decoupling per VDD pin |
| Operating Temp | -40°C to +85°C - qualified for industrial-grade embedded and computing platforms |
Pinout & Package
Package: 16-pin TSSOP (L16), 173mil wide, lead-free and RoHS 3 compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 S0 | Frequency select input | LSB of 2-bit output frequency code (00=25MHz, 01=100MHz, etc.) |
| 2 S1 | Frequency select input | MSB of 2-bit output frequency code |
| 3 SS0 | Spread select input | LSB of 2-bit spread control (00=no spread, 01=-0.5%, etc.) |
| 4 X1/CLK | Clock input | Primary 25MHz crystal or clock source connection point |
| 5 X2 | Crytal output | Secondary crystal terminal; left unconnected when using external clock |
| 6 OE | Output enable | Active-low tri-state control for all HCSL outputs |
| 7 GNDX | Crytal ground | Dedicated ground return for crystal circuit to minimize noise coupling |
| 8 SS1 | Spread select input | MSB of 2-bit spread control |
| 9 IREF | Current reference output | Connects to 475Ω resistor to set 2.32mA reference; scales output drive |
| 10 CLK1 | HCSL output | True leg of second differential clock pair (100Ω differential impedance) |
| 11 CLK1̅ | HCSL output | Complement leg of second differential clock pair |
| 12 VDDA | Analog power | 3.3V supply for PLL and analog output stages; separate from digital VDDX |
| 13 GNDA | Analog ground | Return path for analog circuits and HCSL outputs |
| 14 CLK0 | HCSL output | True leg of first differential clock pair |
| 15 CLK0̅ | HCSL output | Complement leg of first differential clock pair |
| 16 VDDX | Digital power | 3.3V supply for control logic and input buffers |
Key Features
| Feature | Design Value |
|---|---|
| PCIe 2.0 compliance | Validated RMS jitter ≤3.1ps at 100MHz output - enables direct use in PCIe root complex and endpoint designs |
| HCSL output structure | 0.8V current-mode differential driver with 50ps max inter-pair skew - matches PCI Express physical layer requirements |
| External configuration interface | Four dedicated control pins (S0/S1/SS0/SS1) with internal pull-ups - eliminates need for configuration EEPROM or MCU intervention |
| Crystal input support | Optimized for 25MHz parallel-resonant crystals with ≤300ppm tolerance - reduces BOM count vs. oscillator-based solutions |
| Thermal performance | θJA = 90°C/W (TSSOP) - supports operation up to +85°C ambient without forced airflow in compact PCB layouts |
Applications
| PCI Express Root Complex | Embedded Computing Backplane |
|---|---|
Use Scenario: Clock distribution for CPU-to-chipset PCIe 2.0 x16 link in industrial server motherboard. IC Role / Device Role / Timing Role: Primary spread spectrum clock generator providing synchronized 100MHz HCSL clocks to both CPU and PCH. Use Value: Reduces system-level EMI by >10dB at 100MHz harmonics while maintaining PCIe 2.0 jitter compliance. | Use Scenario: Clock source for multi-slot PCIe expansion backplane in ruggedized edge gateway. IC Role / Device Role / Timing Role: Central clock synthesizer delivering matched 125MHz HCSL clocks to four downstream slot controllers. Use Value: Enables deterministic inter-slot skew <50ps and supports -40°C to +85°C operation without thermal derating. |
| Network Interface Card (NIC) | Storage Controller Board |
Use Scenario: Low-jitter clocking for 10GbE controller and PCIe 2.0 x4 host interface on dual-port NIC. IC Role / Device Role / Timing Role: Dual-output generator supplying 125MHz to PHY and 200MHz to PCIe controller. Use Value: Eliminates need for two discrete oscillators; shared 25MHz crystal reduces layout area and cost. | Use Scenario: Timing source for SAS/SATA controller and PCIe bridge on enterprise SSD controller card. IC Role / Device Role / Timing Role: Spread spectrum clock generator providing 100MHz HCSL clocks to both storage PHY and PCIe switch. Use Value: Meets FCC Class B emissions limits without added shielding or ferrites, lowering system BOM cost. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar spread spectrum clock generator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| IDT8T49N242A | LVDS-only outputs; supports 1.8V/2.5V/3.3V supplies; higher integration with programmable spread and frequency via I²C | Requires MCU firmware control; not pin-compatible; better suited for systems needing dynamic reconfiguration | Select when I²C configurability and multi-voltage support outweigh need for simple hardware pin-strapping |
| ICS843002AGI | Single 100MHz HCSL output; no spread spectrum; lower jitter (1.8ps RMS); fixed-frequency only | Lacks spread control and dual outputs; used where EMI is managed elsewhere (e.g., chassis shielding) | Select when absolute lowest jitter is critical and spread spectrum is unnecessary or handled upstream |
Compared with IDT8T49N242A and ICS843002AGI, the PI6C557-03ALE uniquely balances PCIe 2.0 compliance, hardware-configurable spread spectrum, dual HCSL outputs, and TSSOP-16 footprint - making it optimal for cost-sensitive, fixed-function PCIe clocking where MCU overhead and board space are constrained.
Availability
PI6C557-03ALE is available at Aetrix Electronics and suitable for PCIe 2.0 add-in cards, industrial embedded computing motherboards, and network interface designs requiring stable component supply and EMI-reduced clocking.
Supply support for PI6C557-03ALE 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
Diodes Incorporated is a global manufacturer of discrete semiconductors and integrated circuits, specializing in high-performance, high-reliability components for power management, signal integrity, and timing applications.
The PI6C557-03ALE belongs to Diodes' Pericom-branded clock generation product line, engineered specifically for EMI suppression in high-speed serial interfaces including PCIe 2.0, SATA, and Ethernet PHY clock trees.
FAQ
What crystal specifications are required for reliable PI6C557-03ALE operation?
The PI6C557-03ALE requires a 25MHz fundamental-mode parallel-resonant crystal with load capacitance of 18pF and frequency tolerance ≤±30ppm over -40°C to +85°C. Recommended part numbers include GC2500003 (49S/SMD, 4.0mm), FY2500081 (5x3.2mm), and FL2500047 (3.2x2.5mm). External load capacitors must be calculated as (CL − 8) × 2 pF.
How is HCSL output termination implemented on the PCB?
HCSL outputs require external series resistors (33Ω) and ground-return resistors (49.9Ω) per PCI Express Layout Guidelines. Each differential pair (CLK0/CLK0̅, CLK1/CLK1̅) must be routed as controlled-impedance 100Ω differential traces, with non-coupled segments (L1/L2/L3) limited to ≤0.5", ≤0.2", and ≤0.2" respectively before transitioning to coupled routing.
Can the PI6C557-03ALE be configured for LVDS output levels?
Yes - the PI6C557-03ALE supports LVDS-compatible voltage levels when terminated with 100Ω differential load and 150Ω ground-return resistors (RP = RQ = 100Ω, RT = 150Ω). This configuration yields ~350mV differential swing and complies with LVDS electrical standards, though it does not provide true LVDS current-source drive.
What is the function of the IREF pin and how is it used in design?
The IREF pin provides a precision 2.32mA current reference when a 475Ω resistor is connected to ground. This sets the internal current mirror ratio (IOH = 6 × IREF), directly determining HCSL output drive strength. Accurate IREF biasing ensures consistent 0.8V common-mode voltage and crossing-point stability across temperature and process variation.
PI6C557-03ALE Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- PLL:
- Yes
- Main Purpose:
- Ethernet, PCI Express (PCIe)
- Input:
- HCSL, Crystal
- Output:
- HCSL, LVDS
- Number of Circuits:
- 1
- Ratio - Input:Output:
- 1:2
- Differential - Input:Output:
- No/Yes
- Frequency - Max:
- 200MHz
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-TSSOP
PI6C557-03ALE FAQ
1.How can I place an order for PI6C557-03ALE through Aetrix?
Please submit a Request for Quotation (RFQ) for PI6C557-03ALE on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PI6C557-03ALE reliable?
The price and inventory of PI6C557-03ALE are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PI6C557-03ALE is usually 5 days.
3.What payment methods are accepted for PI6C557-03ALE?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PI6C557-03ALE transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PI6C557-03ALE?
PI6C557-03ALE orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PI6C557-03ALE order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PI6C557-03ALE?
For technical support, including PI6C557-03ALE datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PI6C557-03ALE requirements.
6.How does Aetrix verify that PI6C557-03ALE is sourced from the original manufacturer or authorized distributors?
All PI6C557-03ALE products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PI6C557-03ALE meets industry standards.
7.What is the process for return or replacement of PI6C557-03ALE?
All PI6C557-03ALE units undergo pre-shipment inspection (PSI). If there is an issue with PI6C557-03ALE, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PI6C557-03ALE part is unused and in its original packaging.
Return procedure for PI6C557-03ALE:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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