NXP Semiconductors SSTUG32868ET/G,518

Overview

SSTUG32868ET/G from NXP Semiconductors is a 1.8 V, 28-bit, 1:2 configurable registered buffer with integrated parity checking, designed specifically for DDR2-1G RDIMM applications in 2R×4 high-density memory modules. It integrates dual JEDEC-standard register functionality into one TFBGA176 package, supports up to 450 MHz clock frequency, delivers controlled multi-impedance output drivers, and features open-drain QERR error indication (active LOW).

For engineers reviewing the SSTUG32868ET/G datasheet, SSTUG32868ET/G pinout, SSTUG32868ET/G application, or SSTUG32868ET/G equivalent, key selection criteria include its 28-bit 1:2 register architecture, SSTL_18 data input compatibility, differential CK/CK clock interface, permanent high-output-drive configuration, and dual chip-select gating for low-power DIMM operation.

Technical Context

The SSTUG32868ET/G implements a dual-register architecture (Register A and Register B) selected via LVCMOS C input, enabling two distinct 22-bit data routing configurations per register bank. Its parity engine accepts PAR_IN one clock cycle after data, compares against D1–D28 inputs (subset dependent on C state), and asserts QERR two cycles later-latched LOW for ≥2 clocks or until RESET.

It uses differential CK/CK inputs with 600 mV minimum VID and 0.675–1.125 V common-mode range, supports SSTL_18 data inputs (VIH(AC) = Vref + 0.25 V), and provides gated outputs (QnA/QnB) disabled when CSGEN, DCS0, and DCS1 are HIGH-enabling low-power standby without board-level changes.

Key Specifications

Pinout & Package

Package: 176-ball thin fine-pitch ball grid array (TFBGA), 8 × 22 grid, 0.65 mm pitch, 6 mm × 15 mm body size, 0.7 mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V2225L15PF and NB3N551DR2G, the SSTUG32868ET/G uniquely delivers 28-bit 1:2 registered buffering with hardware parity, SSTL_18 compatibility, differential clock interface, and 450 MHz performance in a space-efficient TFBGA176-making it irreplaceable for modern DDR2-900 RDIMM designs requiring reliability and density.

Availability

SSTUG32868ET/G is available at Aetrix Electronics and suitable for server memory modules, enterprise storage controllers, and communications baseband cards requiring stable component supply, full lifecycle support, and guaranteed traceability.

Supply support for SSTUG32868ET/G 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 is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and communication markets.

The SSTUG32868ET/G belongs to NXP's SSTU family of DDR2 registered buffers, engineered specifically for high-density RDIMM applications demanding low-latency re-driving, hardware parity, and robust signal integrity at 450 MHz.

FAQ

What is the primary function of the SSTUG32868ET/G in a DDR2 RDIMM?

The SSTUG32868ET/G serves as a 28-bit, 1:2 configurable registered buffer that re-drives memory controller address, command, and data signals to two ranks of DDR2 SDRAM on a single DIMM. It integrates parity checking across 22 data bits and provides open-drain QERR output for hardware-level error detection-critical for server-class RDIMM reliability. Its dual-register architecture and four chip-select inputs enable flexible, low-power memory subsystem design.

How does the C input affect the SSTUG32868ET/G pin mapping and data routing?

The C input on the SSTUG32868ET/G selects between Register A (C = LOW) and Register B (C = HIGH), changing which subset of D1–D28 inputs and Q1A–Q28A/Q1B–Q28B outputs are active. In Register A mode, D1–D5, D7, D9–D12, and D17–D28 are used; in Register B mode, D1–D12, D17–D20, D22, and D24–D28 are active. This allows board designers to optimize signal routing for specific DIMM layouts without changing the physical part.

What is the timing relationship between data input, PAR_IN, and QERR assertion in the SSTUG32868ET/G?

In the SSTUG32868ET/G, PAR_IN arrives one clock cycle after the corresponding data input (e.g., data at clock edge m, PAR_IN at m+1). The QERR output is generated two clock cycles after the data (at m+2) and becomes valid at m+3. If a parity error occurs, QERR is driven LOW and latched for a minimum of two clock cycles-or until RESET is asserted LOW-ensuring reliable error capture even during low-power modes.

Can the SSTUG32868ET/G operate in low-power mode, and how is it enabled?

Yes, the SSTUG32868ET/G supports low-power active mode. When CSGEN, DCS0, and DCS1 are all driven HIGH, the device gates Qn outputs from changing state, reducing dynamic power consumption. DCS2 and DCS3 operate identically for parity control but lack corresponding QCS outputs. To enter full low-power standby, RESET must be driven LOW-disabling differential receivers and forcing all outputs LOW except QERR, which goes HIGH.

What are the key electrical specifications that ensure signal integrity on high-speed DDR2 DIMMs using the SSTUG32868ET/G?

The SSTUG32868ET/G ensures DDR2 signal integrity via 7 Ω instantaneous / 53 Ω steady-state output impedance, 1–4 V/ns controlled slew rates, 1.0–1.4 ns propagation delay (tPDM), and SSTL_18-compatible inputs with VIH(AC) = Vref + 0.25 V and VIL(AC) = Vref − 0.25 V. Its differential CK/CK interface requires 600 mV minimum VID and operates within 0.675–1.125 V common-mode range-meeting JEDEC DDR2 timing and noise margin requirements at 450 MHz.