Winbond Electronics Corporation W9751G8NB25I TR

Overview

W9751G8NB25I TR from Winbond is a 512 Mbit DDR2 SDRAM organized as 16M × 4 banks × 8 bits, operating at DDR2-800 speed (5-5-5 or 6-6-6), with 1.8 V supply, industrial temperature range (−40°C to +95°C), and VFBGA-60 (8 mm × 9.5 mm) packaging. It serves as main memory in embedded networking and industrial control systems requiring JEDEC-compliant synchronous DRAM with on-die termination and OCD calibration.

For engineers reviewing the W9751G8NB25I TR datasheet, W9751G8NB25I TR pinout, W9751G8NB25I TR application, or W9751G8NB25I TR equivalent, key selection criteria include tRCD = 12.5 ns, tRP = 12.5 ns, ODT support, differential clock interface (CLK/CLK), and SSTL_18 I/O compatibility for signal integrity in high-density PCB layouts.

Technical Context

This DDR2 SDRAM implements a double-data-rate architecture synchronized to differential CLK/CLK inputs, with DLL-aligned DQ/DQS timing and source-synchronous data strobes. It supports programmable CAS latency (CL = 3–7), additive latency (AL = 0–2), and write latency WL = RL − 1, enabling flexible timing tuning across varying system clock domains.

Functional operation includes auto-precharge, burst interrupt, posted CAS, and dual power-down modes (precharged/active). On-die termination (ODT) and off-chip driver (OCD) impedance adjustment are controlled via extended mode registers EMR(1)–EMR(3), allowing dynamic signal integrity optimization without external resistors.

Key Specifications

Pinout & Package

VFBGA-60 package (8 mm × 9.5 mm, 1.0 mm height), RoHS-compliant, lead-free. Ball pitch: 0.8 mm. Compatible with standard reflow profiles for fine-pitch BGAs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MT47H128M8HQ-25E, W9751G8NB25I TR adds guaranteed 95°C case operation with automatic tREFI halving; versus IS42S16160F-25BLI, it retains pin compatibility and 8-bit bus simplicity while delivering identical thermal performance.

Availability

W9751G8NB25I TR is available at Aetrix Electronics and suitable for industrial automation, network infrastructure, medical electronics, and test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for W9751G8NB25I TR 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

Winbond Electronics is a Taiwan-based semiconductor company specializing in specialty memory solutions including NOR/NAND Flash, SRAM, and DRAM products for industrial, automotive, and communications markets.

The W9751G8NB series targets cost-sensitive, thermally demanding embedded systems needing JEDEC-standard DDR2 with industrial-grade reliability and integrated signal integrity features like ODT and OCD.

FAQ

What is the maximum supported CAS latency for W9751G8NB25I TR?

W9751G8NB25I TR supports CAS latency (CL) values of 3, 4, 5, 6, and 7. At its rated DDR2-800 speed grade (−25/25I/25J), CL=5 and CL=6 are most commonly used, corresponding to tCK = 2.5 ns and 2.5 ns minimum respectively. CL=3 is supported only at slower clock frequencies (tCK ≥ 5 ns) and is not recommended for DDR2-800 operation. The actual CL setting is configured via the Mode Register Set (MRS) command during initialization.

Does W9751G8NB25I TR require external termination resistors?

No, W9751G8NB25I TR integrates on-die termination (ODT) that can be enabled via the ODT pin and configured through Extended Mode Register EMR(1). When activated, ODT provides 75 Ω or 150 Ω termination on DQ and DQS lines during read/write operations, eliminating the need for external parallel resistors and simplifying PCB layout. External termination is only required if ODT is disabled or for non-strobed control/address nets.

How is the refresh interval handled at elevated temperatures for W9751G8NB25I TR?

W9751G8NB25I TR automatically halves its refresh interval from 7.8 μs to 3.9 μs when case temperature exceeds 85°C, as mandated by JEDEC for DDR2 devices. This is achieved by setting A7 = "1" in EMR(2) to enable high-temperature self-refresh mode. The device supports this extended range up to +95°C, and the refresh controller must issue commands at double frequency during this condition to prevent data loss.

Can W9751G8NB25I TR operate with single-ended clock inputs?

No, W9751G8NB25I TR requires differential clock inputs (CLK and CLK) as defined by the DDR2 standard. All commands, addresses, and internal timing are referenced to the crossing points of these differential signals. Single-ended clocking is not supported and will result in undefined behavior or failure to initialize. The differential pair must be routed with matched length and controlled impedance (typically 100 Ω differential) to ensure proper DLL lock and timing margin.

What is the purpose of the DM/RDQS ball on W9751G8NB25I TR?

The DM/RDQS ball on W9751G8NB25I TR serves dual functions: as DM (Data Mask) during write operations to suppress individual byte lanes, or as RDQS (Read Data Strobe) during reads when enabled via EMR(1)[A11] = 1. When RDQS is active, it outputs a dedicated read strobe independent of DQS, improving timing margin in systems with asymmetric read/write paths. DM is sampled on both edges of DQS, allowing per-byte masking aligned to burst boundaries.