Diodes Incorporated PI6C20400ALEX

Overview

PI6C20400ALEX from Diodes Incorporated is a PCIe® 2.0-compliant 1:4 differential clock driver IC designed as a companion to the PI6C410BS clock synthesizer. It distributes a 0.7V HCSL SRC input across four differential output pairs (OUT0–OUT3) with selectable PLL or bypass mode, <50ps cycle-to-cycle jitter, and <1ps additive RMS phase jitter - deployed in Intel PCIe chipset-based server motherboards and storage controllers.

For engineers reviewing the PI6C20400ALEX datasheet, PI6C20400ALEX pinout, PI6C20400ALEX application, or PI6C20400ALEX equivalent, key selection criteria include differential output skew (<50ps), SMBus-programmable PLL bandwidth, tristate control via OE_0/OE_3/SRC_STOP#/PWRDWN#, and compatibility with 100–400 MHz bypass-mode operation for PCIe Gen2 timing distribution.

Technical Context

The PI6C20400ALEX implements a dual-path architecture: a low-jitter PLL path (100 MHz nominal) and a direct bypass path (100–400 MHz), selected via the 3.3V LVTTL PLL/BYPASS# pin. Its current-mode HCSL outputs are configured using an external 475Ω IREF resistor, delivering 6×IREF (≈13.9 mA) per output pair into 50Ω DC-coupled loads.

It operates as an SMBus slave device (7-bit address 0x6E) supporting indexed block read/write for register-level control of output enable, PLL bandwidth, SRC_STOP# behavior, and power-down sequencing. All outputs enter high-impedance state when SRC_STOP# or PWRDWN# is asserted low, with Tdrive_PwrDwn# <300 µs and output stabilization <1 ms after de-assertion.

Key Specifications

Pinout & Package

PI6C20400ALEX is packaged in a 28-pin TSSOP (L28, 173-mil wide), RoHS- and halogen-free "Green" compliant. Pin functions are validated per Diodes DS43442 Rev 2-2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PCIe clock distribution applications.

Compared with IDT8T49N242A and ICS843002AG-01, PI6C20400ALEX uniquely combines HCSL output compatibility, SMBus-configurable tristate control, and dual-path (PLL/bypass) operation in a 28-pin TSSOP - enabling dynamic PCIe lane management and jitter-optimized timing in space-constrained server platforms.

Availability

PI6C20400ALEX is available at Aetrix Electronics and suitable for PCIe Gen2 server motherboard design, enterprise SSD controller development, and Intel chipset-based storage appliance manufacturing requiring stable component supply and long-term lifecycle support.

Supply support for PI6C20400ALEX 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 analog, logic, and timing solutions for computing, industrial, and communications markets.

The PI6C20400ALEX belongs to Diodes' Pericom timing product line, engineered specifically for PCIe 2.0-compliant clock distribution in high-density server and storage platforms where low additive jitter and flexible output control are critical.

FAQ

What is the function of the IREF pin on PI6C20400ALEX?

The IREF pin connects to an external 475Ω 1% resistor to set the reference current (2.32 mA), which scales the output current to 6×IREF (≈13.9 mA) per HCSL output pair. This defines the drive strength into 50Ω DC-coupled loads and directly impacts output voltage swing (0.7V) and edge rate. Incorrect resistor value causes out-of-spec output amplitude and jitter performance.

Can PI6C20400ALEX operate without an external crystal?

Yes - PI6C20400ALEX does not require an external crystal. It is a clock buffer, not a clock generator. It accepts an external differential HCSL clock (SRC/SRC#) and redistributes it either through its internal PLL (100 MHz) or directly in bypass mode (100–400 MHz). Crystal-less operation is inherent to its fanout architecture.

How does the OE_INV pin affect output enable behavior?

The OE_INV pin (Pin 25) inverts the logic polarity of OE_0, OE_3, SRC_STOP#, and PWRDWN#. When OE_INV = 0, these signals operate with standard active-high (OE) or active-low (STOP#/PWRDWN#) behavior. When OE_INV = 1, OE_0/OE_3 become active-low, and STOP#/PWRDWN# become active-high - enabling consistent signal polarity across mixed-control systems.

Is PI6C20400ALEX pin-compatible with PI6C20400AHEX?

Yes - PI6C20400ALEX (TSSOP, L28) and PI6C20400AHEX (SSOP, H28) share identical pin numbering, electrical functionality, and register mapping. The only difference is package mechanicals: L28 is 173-mil wide, H28 is 209-mil wide. PCB layout must accommodate the respective footprint, but schematic design and firmware are fully interchangeable.