NXP Semiconductors SSTUH32866EC/G,557

Overview

SSTUH32866EC/G,557 from NXP Semiconductors (formerly Philips Semiconductors) is a 1.8 V configurable DDR2 registered buffer with integrated parity checking, designed for RDIMM applications. It supports two modes: 25-bit 1:1 or 14-bit 1:2 topology, delivers ≤1.8 ns single-bit propagation delay, operates up to 450 MHz, and features open-drain QERR output for active-LOW parity error indication in even-parity systems.

For engineers reviewing the SSTUH32866EC/G,557 datasheet, SSTUH32866EC/G,557 pinout, SSTUH32866EC/G,557 application, or SSTUH32866EC/G,557 equivalent, this device is critical for DDR2 memory subsystems requiring robust data integrity, high-drive capability for stacked DRAM loads, and JEDEC-compliant timing in registered DIMM designs.

Technical Context

The SSTUH32866EC/G,557 uses differential CK/CK inputs synchronized at the crossing of CK rising and CK falling edges to register SSTL_18 data inputs (D1–D25 or subsets per configuration). Its parity logic computes even parity across DIMM-independent data inputs plus PAR_IN, latching QERR LOW for two clock cycles upon error detection.

Configuration is controlled by LVCMOS C0/C1 pins: C1 selects 1:1 (C1=0) vs. 1:2 (C1=1); C0 selects Register A (C0=0) or Register B (C0=1) in 1:2 mode. Chip-select gating (DCS/CSR) disables outputs to reduce dynamic power, while RESET asynchronously clears registers and forces all outputs LOW.

Key Specifications

Pinout & Package

Package: 96-ball LFBGA (13.5 mm × 5.5 mm, 0.8 mm pitch), SOT536-1 footprint - Optimized for high-density DDR2 module layout with thermal and electrical performance for memory subsystems.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DDR2 registered buffer with parity applications.

Compared with IDT72V2235L15PF and NB3N502DR2G, the SSTUH32866EC/G,557 uniquely integrates configurable topology, on-die parity checking, and DDR2-optimized drive strength - eliminating external components and enabling JEDEC-compliant RDIMM designs with built-in data integrity.

Availability

SSTUH32866EC/G,557 is available at Aetrix Electronics and suitable for DDR2 registered DIMM manufacturing, server memory module refurbishment, and industrial embedded memory subsystems requiring stable component supply and long-term lifecycle support.

Supply support for SSTUH32866EC/G,557 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

NXP Semiconductors, formerly Philips Semiconductors, is a global leader in high-performance analog and mixed-signal ICs for memory, automotive, and industrial applications.

The SSTUH32866EC/G,557 belongs to NXP's DDR2 registered buffer product line, engineered specifically to meet JEDEC JESD82-7 requirements for parity-enabled RDIMMs in high-reliability computing environments.

FAQ

What is the primary function of the SSTUH32866EC/G,557 in a DDR2 memory system?

The SSTUH32866EC/G,557 serves as a configurable registered buffer with integrated even-parity checking for DDR2 RDIMMs. It registers address, command, and data signals using differential CK/CK inputs, drives heavy capacitive loads with ±12 mA output strength, and validates parity via PAR_IN comparison to generate QERR on mismatch - all within a single 96-ball LFBGA package.

How does the SSTUH32866EC/G,557 support both 1:1 and 1:2 topologies?

The SSTUH32866EC/G,557 uses two LVCMOS configuration pins: C1 selects mode (C1=0 → 25-bit 1:1; C1=1 → 14-bit 1:2), and C0 selects register identity in 1:2 mode (C0=0 → Register A; C0=1 → Register B). Pin mappings differ per mode (see Figures 4–6), and data input/output sets are redefined accordingly - e.g., D2–D25 in 1:1 vs. D2–D14 in Register A 1:2.

What is the timing relationship between PAR_IN and its corresponding data inputs on the SSTUH32866EC/G,557?

PAR_IN arrives one clock cycle after the data inputs it validates - for example, PAR_IN sampled at clock edge m corresponds to D-inputs sampled at edge m−1. In cascaded 1:2 configurations, PAR_IN for the second device is driven by PPO from the first device, maintaining correct temporal alignment across the chain.

Can the SSTUH32866EC/G,557 operate without an external VREF source?

No - the SSTUH32866EC/G,557 requires an externally supplied VREF at 0.49×VDD to 0.51×VDD (typically 0.9 V at 1.8 V VDD) to bias its SSTL_18 input receivers. VREF must be held at a valid level before RESET release and maintained during operation; floating VREF causes undefined input thresholds and potential functional failure.

What happens to QERR output when a parity error occurs on the SSTUH32866EC/G,557?

When a parity error is detected, the SSTUH32866EC/G,557 drives QERR LOW and latches it for two full clock cycles. The output remains LOW until either two clocks elapse or RESET is asserted LOW. This behavior ensures reliable capture by system monitoring logic without requiring strobing or edge detection.