Diodes Incorporated PI6CU877NFE

Overview

PI6CU877NFE from Pericom Semiconductor is a 1.8V PLL-based zero-delay clock driver optimized for Registered DDR2 DIMM applications, supporting 160–270 MHz application clock frequency with differential CLK/CLK input and eleven differential output pairs (Y[0:9], Y[0:9]; FBOUT, FBOUT). It features spread spectrum clocking (SSC) tracking, <40 ps cycle-to-cycle jitter, <40 ps output skew, and LVCMOS OE/OS control logic. Used in DDR2-533/400 memory subsystems on server and workstation motherboards.

For engineers reviewing the PI6CU877NFE datasheet, PI6CU877NFE pinout, PI6CU877NFE application, or PI6CU877NFE equivalent, key selection criteria include differential clock distribution integrity, PLL lock stability under SSC modulation, low-power state behavior (LD* detection), AVDD/VDDQ supply separation, and VFBGA-52 thermal/mechanical compatibility with high-density DIMM layouts.

Technical Context

The PI6CU877NFE implements a fully integrated PLL with external feedback path via FBIN/FBIN pins to synchronize all eleven differential outputs to the reference clock. Its loop bandwidth is tuned to 2.0 MHz to minimize SSC-induced skew while maintaining phase lock across 160–270 MHz application frequencies.

Power management includes dual-domain control: AVDD powers the analog PLL core (bypassed when grounded), while VDDQ supplies the 1.8V differential output drivers and LVCMOS inputs (OE, OS). The LD* logic-detect circuit disables the PLL and all outputs when both CLK and CLK are held low, enabling deterministic power-down without external sequencing.

Key Specifications

Pinout & Package

Package: 52-ball Very Thin Fine-Pitch Ball Grid Array (VFBGA-NF), Pb-free and RoHS-compliant, 5 mm × 5 mm footprint with 0.5 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT 85411AMLFT and ON Semi NB3N502DG, the PI6CU877NFE uniquely combines DDR2-533 timing compliance, differential feedback capability, and OS-gated Y7 free-run mode-making it the only option that satisfies JEDEC-compliant RDIMM clock architecture with suspend-aware operation.

Availability

PI6CU877NFE is available at Aetrix Electronics and suitable for server memory modules, industrial control memory boards, and embedded computing platforms requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for PI6CU877NFE 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

Pericom Semiconductor (now part of Diodes Incorporated) is a fabless provider of high-performance interface, timing, and signal-integrity solutions for computing, communications, and consumer electronics.

The PI6CU877NFE belongs to Pericom's DDR2 clock driver product line, engineered specifically to meet JEDEC requirements for registered DIMM clock distribution-including SSC tracking, low skew, and dual-supply domain control for testability and power management.

FAQ

What happens to the PLL when AVDD is grounded?

When AVDD is grounded, the PLL is disabled and bypassed-CLK/CLK is routed directly to FBOUT/FBOUT, and all Y[0:9]/Y[0:9] outputs are forced low. VDDQ must remain powered (1.7–1.9 V) to maintain I/O bias, but no timing parameters are guaranteed in this test mode.

How does OS = LOW affect Y7/Y7 behavior when OE = LOW?

When OS = LOW, OE has no effect on Y7/Y7-they remain active and free-running regardless of OE state. This allows continuous clocking to a designated memory rank during system suspend, while other outputs (Y0–Y6, Y8–Y9) are disabled by OE = LOW.

Can the PI6CU877NFE track spread spectrum clocking without violating jitter specs?

Yes-the PI6CU877NFE's PLL is designed to track SSC modulation up to ±0.5% deviation at 30–33 kHz while maintaining ≤±40 ps cycle-to-cycle jitter and ≤40 ps output skew, as verified under JEDEC-aligned test conditions with specified load networks.

What is the stabilization time after power-up or wake-from-power-down?

The PLL requires ≤15 µs to achieve phase lock after power-up or after exiting LD*-triggered power-down (when CLK/CLK return from low to active). During this time, outputs remain in high-impedance or low state per OE/OS configuration until lock is achieved.