Winbond Electronics Corporation W971GG8SS25I

Overview

W971GG8SS25I from Winbond is a 1G-bit DDR2 SDRAM organized as 16M × 8 banks × 8 bits, operating at DDR2-800 speed (5-5-5 or 6-6-6 timing), with 1.8 V ± 0.1 V supply, CAS latency configurable from 3 to 7, and industrial temperature range support (–40°C to +95°C). It serves as main system memory in embedded controllers, network processors, and industrial HMIs requiring reliable high-bandwidth data buffering.

For engineers reviewing the W971GG8SS25I datasheet, W971GG8SS25I pinout, W971GG8SS25I application, or W971GG8SS25I equivalent, key selection considerations include its industrial-grade thermal rating, WBGA-60 package compatibility, ODT/OCD signal integrity features, and JEDEC-compliant DDR2-800 timing margins for stable multi-bank burst operations.

Technical Context

This DDR2 SDRAM implements a double-data-rate architecture synchronized to differential CLK/CLK inputs, with bi-directional DQS/DQS strobes edge-aligned on reads and center-aligned on writes. Its DLL aligns DQ and DQS transitions to clock edges, enabling precise timing control across temperature and voltage variations.

The device supports programmable additive latency (AL = 0–2), auto-precharge, on-die termination (ODT), off-chip driver impedance adjustment (OCD), and both self-refresh and auto-refresh modes. Command decoding occurs on every positive CLK edge, while data and DM are sampled on both DQS edges - ensuring robust source-synchronous I/O timing compliance per JEDEC JESD79-2F.

Key Specifications

Pinout & Package

W971GG8SS25I is packaged in a lead-free, RoHS-compliant WBGA-60 (8 mm × 9.5 mm) ball grid array with 0.8 mm pitch. The package isolates VSSQ (DQ ground) and VSSDL (DLL ground) for noise immunity, and includes dedicated VDDL (1.8 V DLL supply) and VREF (input reference) balls.

Key Features

Applications

Equivalent & Alternatives

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

Compared with W971GG8SS25I, MT47H128M8HQ-25E offers identical industrial rating and speed but demands layout changes, while IS42S16160F-25BLI trades temperature robustness for wider data bus and lower-cost packaging - making W971GG8SS25I optimal for compact, thermally demanding x8 DDR2 implementations.

Availability

W971GG8SS25I is available at Aetrix Electronics and suitable for industrial HMIs, network processors, medical imaging control units, and automated test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for W971GG8SS25I 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, PSRAM, and DDR SDRAM products for industrial, automotive, and communications markets.

W971GG8SS25I belongs to Winbond's DDR2 SDRAM product line, designed specifically for cost-sensitive, thermally demanding embedded systems requiring JEDEC-compliant high-speed memory with industrial-grade reliability and long-term supply assurance.

FAQ

What is the maximum supported CAS latency for W971GG8SS25I?

W971GG8SS25I supports CAS latency values of 3, 4, 5, 6, and 7 - selectable via the Mode Register Set (MRS) command. At DDR2-800 speed (400 MHz clock), CL=7 corresponds to a tAA of 3.5 ns. All CL settings are fully validated across the –40°C to +95°C operating range, with timing parameters guaranteed per JEDEC JESD79-2F.

Does W971GG8SS25I require external termination resistors?

No, W971GG8SS25I integrates on-die termination (ODT) controlled via the ODT pin and extended mode registers. When enabled, it provides programmable termination resistance on DQ and DQS lines, eliminating the need for external parallel resistors. This reduces PCB component count and improves signal integrity in high-speed layouts - a key design advantage of the W971GG8SS25I.

How does the OCD calibration feature work in W971GG8SS25I?

W971GG8SS25I supports Off-Chip Driver (OCD) impedance adjustment through an initialization sequence that calibrates output driver strength against a reference resistor (typically 50 Ω). This calibration occurs after power-up and DLL enable, using EMRS commands to EMR(1). The result is matched drive strength across all DQ pins, minimizing skew and improving eye diagram margins - a core capability of the W971GG8SS25I.

What is the refresh requirement for W971GG8SS25I at 95°C?

At case temperatures between 85°C and 95°C, W971GG8SS25I requires doubled refresh frequency: tREFI = 3.9 µS (vs. 7.8 µS at ≤85°C), achieved by issuing Auto Refresh commands every 32 ms. This is mandated by JEDEC and enabled by setting A7=1 in EMR(2). Failure to meet this interval risks data retention loss - a critical specification for the W971GG8SS25I in high-temperature deployments.

Is W971GG8SS25I pin-compatible with other Winbond DDR2 SDRAMs like W971GG6SB?

No, W971GG8SS25I is not pin-compatible with W971GG6SB. While both use WBGA-60 packages, their ball maps differ significantly - particularly in DQS/DQS placement, VREF location, and ODT assignment. The W971GG8SS25I datasheet specifies unique ball functions (e.g., A2 as NU/RDQS, B7/K7 as DQS/DQS), and no Winbond documentation claims pin compatibility between these variants. Direct substitution would require PCB redesign.