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Diodes Incorporated PI6C557-03ALEX
- Part No.:
- PI6C557-03ALEX
- Manufacturer:
- Diodes Incorporated
- Category:
- Application Specific Clock/Timing
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
PI6C557-03ALEX.pdf
- Description:
- IC CLOCK GENERATOR 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,065
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Product details
Overview
PI6C557-03ALEX from Diodes Incorporated is a PCIe 2.0-compliant spread spectrum clock generator with two HCSL differential outputs, phase jitter of 2.1ps RMS (typ), 3.3V supply, and selectable output frequencies of 25/100/125/200 MHz for PC and embedded timing systems.
For engineers reviewing the PI6C557-03ALEX datasheet, PI6C557-03ALEX pinout, PI6C557-03ALEX application, or PI6C557-03ALEX equivalent, key selection criteria include PCIe 2.0 RMS jitter compliance (≤3.1ps), HCSL current-mode drive capability (0.8V differential pair), external spread-spectrum control via SS0/SS1 pins, and industrial temperature operation (–40°C to +85°C).
Technical Context
The PI6C557-03ALEX implements a proprietary Phase-Locked Loop architecture optimized for PCIe 2.0 clock synthesis, accepting a 25MHz crystal or single-ended clock input and generating two independent HCSL output pairs at 25/100/125/200 MHz. Frequency selection is controlled by S0/S1 pins per Table 1.
Spread spectrum modulation is configurable via SS0/SS1 pins for –0.5%, –0.75%, or no spread, with modulation frequency fixed at 30–33 kHz. Output enable (OE) provides tri-state control, and IREF pin supports precision current reference setting via external 475Ω resistor for 2.32mA reference and 6×IREF output drive.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Type | HCSL differential pair (0.8V current mode), LVDS-compatible with external termination |
| Input Frequency | 25MHz crystal or single-ended clock - fixed fundamental input for PLL multiplication |
| Output Frequencies | 25MHz, 100MHz, 125MHz, 200MHz - selected via S0/S1 logic pins |
| Phase Jitter (RMS) | 2.1ps typical (PCIe 2.0 compliant at 100MHz output) |
| Cycle-to-Cycle Jitter | 35ps typical - critical for timing margin in high-speed serial links |
| Supply Voltage | 3.3V ±10% - requires dual VDDX/VDDA rails with local 0.01μF decoupling per pin |
| Operating Temp | –40°C to +85°C - qualified for industrial-grade embedded and computing platforms |
Pinout & Package
PI6C557-03ALEX is packaged in a 16-pin TSSOP (173mil width, L package code), RoHS-compliant and halogen-free. Pin layout follows standard JEDEC MO-153 footprint with exposed pad not present.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 (S0, S1) | Frequency select inputs | Binary-coded selection of 25/100/125/200 MHz outputs; internal pull-up resistors |
| 3, 8 (SS0, SS1) | Spread select inputs | Binary-coded selection of –0.5%, –0.75%, or no spread; internal pull-up resistors |
| 4 (X1/CLK), 5 (X2) | Clock input terminals | X1/CLK accepts 25MHz crystal or clock; X2 is crystal output - leave open for clock input mode |
| 6 (OE) | Output enable input | Active-low control: OE = LOW places all CLK outputs in high-impedance state (10μs disable time) |
| 9 (IREF) | Current reference output | Connects to external 475Ω resistor to set 2.32mA reference; output drive = 6×IREF ≈ 13.9mA |
| 10, 11, 14, 15 (CLK1, CLK1, CLK0, CLK0) | Differential HCSL outputs | Two complementary pairs: CLK0/CLK0 and CLK1/CLK1 - require external series and ground termination per PCIe layout guidelines |
| 7, 13 (GNDX, GNDA) | Ground terminals | GNDX: crystal ground; GNDA: analog/output ground - separate return paths reduce noise coupling |
| 12, 16 (VDDA, VDDX) | Power supply terminals | VDDA powers analog/PLL core; VDDX powers crystal oscillator - each requires dedicated 0.01μF decoupling |
Key Features
| Feature | Design Value |
|---|---|
| PCIe 2.0 RMS jitter compliance | 3.1ps max at 100MHz output - meets specification for Gen2 root complex and endpoint timing budgets |
| Configurable spread spectrum | Hardware-selectable –0.5% or –0.75% down-spread via SS0/SS1 pins - reduces EMI without software or register writes |
| HCSL current-mode drive | 0.8V differential swing into 50Ω load - compatible with PCIe slot clock receivers without level-shifting |
| Crystal or clock input flexibility | Single 25MHz input supports both crystal (X1/X2) and external clock (X1 only) modes - simplifies board design reuse |
| Industrial temperature range | –40°C to +85°C operation - validated across full range for reliability in embedded compute and networking equipment |
Applications
| PCI Express Gen2 Root Complex | Embedded Computing Backplane |
|---|---|
|
Use Scenario: Providing reference clocks to multiple PCIe endpoints on a server motherboard with strict EMI limits. IC Role / Device Role / Timing Role: Primary PCIe 2.0 clock generator delivering two synchronized 100MHz HCSL clock pairs to downstream slots and controllers. Use Value: 2.1ps RMS phase jitter ensures setup/hold margin for 5GT/s serial links; –0.75% spread reduces peak radiated emissions by >10dB. |
Use Scenario: Clock distribution in ruggedized industrial computer with fanless cooling and extended thermal cycling. IC Role / Device Role / Timing Role: Low-jitter, spread-spectrum clock source for CPU, chipset, and peripheral bridges operating across –40°C to +85°C. Use Value: Dual-rail power (VDDX/VDDA) and separate GNDX/GNDA minimize supply-induced jitter; TSSOP package supports automated optical inspection. |
| Network Switch Fabric Timing | Storage Controller Reference Clock |
|
Use Scenario: Synchronizing SERDES lanes across multi-port Ethernet switch ASICs requiring deterministic skew. IC Role / Device Role / Timing Role: Low-skew (<50ps) dual-output clock generator feeding 125MHz clocks to PHY and MAC layers. Use Value: Matched propagation delay between CLK0 and CLK1 outputs enables sub-cycle alignment; HCSL drive matches switch ASIC input impedance. |
Use Scenario: Generating 200MHz reference for NVMe SSD controller with PCIe 2.0 x4 interface. IC Role / Device Role / Timing Role: High-frequency clock source configured via S0/S1 for 200MHz output, supporting 5GT/s data rate. Use Value: 35ps cycle-to-cycle jitter preserves eye opening at receiver; OE pin allows dynamic clock gating during low-power states. |
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 |
|---|---|---|---|
| IDT8T49N242B | LVDS-only outputs; integrated EEPROM for programmable spread/frequency; requires I²C configuration | Requires firmware initialization; better for field-upgradable timing schemes but adds boot dependency | Choose when programmability and multi-configuration support outweigh simplicity and cost |
| ICS8430M-01 | Fixed 100MHz output; no spread spectrum; lower jitter (1.8ps RMS); 3.3V only | Lacks frequency/spread selection pins - suitable only for static 100MHz PCIe Gen2 applications | Choose when absolute lowest jitter is required and system design locks frequency/spread at board level |
Compared with IDT8T49N242B and ICS8430M-01, PI6C557-03ALEX delivers hardware-configurable spread and frequency without firmware overhead or EEPROM dependency, while maintaining PCIe 2.0 jitter compliance and industrial temperature robustness in a cost-optimized TSSOP package.
Availability
PI6C557-03ALEX is available at Aetrix Electronics and suitable for PCIe Gen2 server motherboards, industrial embedded computers, network switch fabric timing, and NVMe storage controller reference clocking requiring stable component supply and long-term lifecycle support.
Supply support for PI6C557-03ALEX 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 timing, power management, and signal integrity solutions for computing, industrial, and communications markets.
The PI6C557 product line delivers PCIe-compliant spread spectrum clock generators optimized for EMI reduction in space-constrained embedded and server platforms, with emphasis on hardware configurability and industrial reliability.
FAQ
What crystal specifications are required for PI6C557-03ALEX?
The device requires a 25MHz fundamental-mode parallel-resonant crystal with ≤300ppm frequency tolerance over temperature and 18pF load capacitance. Recommended part numbers include GC2500003 (49S/SMD, ±30ppm) and FL2500047 (3.2×2.5mm, ±20ppm). External crystal capacitors must be set to (CL − 4) × 2 pF - e.g., 24pF for an 18pF crystal.
How is HCSL output termination implemented on the PCB?
HCSL outputs require external series resistors (RS = 33Ω) and ground-return resistors (RT = 49.9Ω) per PCIe Layout Guidelines. The PI6C557-03ALEX drives a 50Ω differential pair; traces must be routed as coupled 100Ω microstrip/stripline with L4 length between 2–16 inches. Termination components must be placed within 0.2 inches of the IC pins.
Can PI6C557-03ALEX operate in LVDS mode?
Yes - the device supports LVDS-compatible voltage levels when configured with RP = RQ = 100Ω and RT = 150Ω terminations per Figure 4. Output common-mode voltage shifts to ~1.2V, and differential swing becomes ~350mV. No internal register change is needed; only external component values differ from HCSL layout.
What is the function of the IREF pin and how is it used?
IREF is a precision current reference output that sets the HCSL output drive strength. A 475Ω resistor to ground yields 2.32mA reference current, producing 13.9mA output drive (6×IREF). This ensures consistent 0.8V differential swing into 50Ω loads. Deviations in RR directly scale output current and affect waveform integrity.
PI6C557-03ALEX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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
PI6C557-03ALEX FAQ
1.How can I place an order for PI6C557-03ALEX through Aetrix?
Please submit a Request for Quotation (RFQ) for PI6C557-03ALEX 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 PI6C557-03ALEX reliable?
The price and inventory of PI6C557-03ALEX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PI6C557-03ALEX is usually 5 days.
3.What payment methods are accepted for PI6C557-03ALEX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PI6C557-03ALEX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PI6C557-03ALEX?
PI6C557-03ALEX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PI6C557-03ALEX 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 PI6C557-03ALEX?
For technical support, including PI6C557-03ALEX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PI6C557-03ALEX requirements.
6.How does Aetrix verify that PI6C557-03ALEX is sourced from the original manufacturer or authorized distributors?
All PI6C557-03ALEX 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 PI6C557-03ALEX meets industry standards.
7.What is the process for return or replacement of PI6C557-03ALEX?
All PI6C557-03ALEX units undergo pre-shipment inspection (PSI). If there is an issue with PI6C557-03ALEX, 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 PI6C557-03ALEX part is unused and in its original packaging.
Return procedure for PI6C557-03ALEX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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