Winbond Electronics Corporation W9725G6KB-25

Overview

W9725G6KB-25 from Winbond is a 256Mb (4M × 4 banks × 16-bit) DDR2 SDRAM compliant with DDR2-800 (5-5-5 or 6-6-6) timing, operating at 1.8 V ±0.1 V supply, supporting CAS Latency 3–7 and burst lengths of 4 or 8. It delivers up to 800 Mb/sec/pin data rates and is used in embedded computing, industrial controllers, and legacy networking equipment requiring synchronous, high-bandwidth memory buffering.

For engineers reviewing the W9725G6KB-25 datasheet, W9725G6KB-25 pinout, W9725G6KB-25 application, or W9725G6KB-25 equivalent, key selection considerations include its WBGA-84 package, SSTL_18 interface compatibility, on-die termination (ODT), OCD impedance calibration, and support for auto-precharge, self-refresh, and differential DQS strobes in source-synchronous I/O operation.

Technical Context

This DDR2 SDRAM implements a 4-bank architecture with prefetch-4 I/O interface and DLL-based clock-data alignment. Its command decoding supports standard DDR2 protocols including posted CAS (AL = 0–2), write latency = read latency −1, and ODT control via dedicated ball (ODT). The device uses edge-aligned read DQS and center-aligned write DQS with bi-directional DQ0–DQ15 bus.

Initialization requires strict sequence: stable 1.8 V supplies, ≥200 µs clock stabilization, CKE assertion, precharge-all, EMRS(2)/EMRS(3)/EMRS(1) for DLL enable and OCD setup, followed by MRS programming and OCD calibration. AC timing adheres to JEDEC DDR2-800 spec with tRCD/tRP/tRC minima of 12.5 ns/12.5 ns/57.5 ns at CL=5.

Key Specifications

Pinout & Package

W9725G6KB-25 is packaged in an 84-ball WBGA (Wafer-Level Ball Grid Array) with 0.8 mm pitch, dimensions 8 mm × 12.5 mm. The package separates VDD/VSS (core) from VDDQ/VSSQ (I/O) for noise isolation, includes dedicated VDDL/VSSDL for DLL power/ground, and features NC balls for layout flexibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with W9725G6KB-25, MT47H64M4BP-25E demands full PCB revision due to package and pinout mismatch, whereas IS42S16400F-25BLI offers drop-in thermal upgrade capability with identical mechanical fit and compatible command set-making it the preferred alternative for ruggedized deployments.

Availability

W9725G6KB-25 is available at Aetrix Electronics and suitable for industrial automation, legacy telecom infrastructure, and medical display systems requiring stable component supply, long-lifecycle support, and JEDEC-compliant DDR2-800 memory performance.

Supply support for W9725G6KB-25 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 for industrial, automotive, and consumer applications.

The W97 series targets cost-sensitive, high-reliability embedded systems needing JEDEC-standard DDR2 memory with robust initialization, ODT, and OCD features - optimized for controllers lacking advanced PHY calibration.

FAQ

What is the maximum clock frequency supported by the W9725G6KB-25?

The W9725G6KB-25 is rated for DDR2-800 operation, meaning it supports a 400 MHz differential clock frequency (tCK = 2.5 ns minimum at CL=5), delivering 800 Mb/sec/pin data transfer rates. This speed grade is validated across its specified operating temperature range (0°C to 85°C case temperature) and requires compliance with JEDEC DDR2-800 timing parameters including tRCD, tRP, and tRC minima.

Does the W9725G6KB-25 support differential DQS signaling?

Yes, the W9725G6KB-25 supports differential DQS signaling via dedicated UDQS/UDQS and LDQS/LDQS balls. This mode must be explicitly enabled through Extended Mode Register Set (EMRS) command to EMR(1) with A10 HIGH. When active, DQS strobes are edge-aligned with read data and center-aligned with write data, improving timing margin in high-speed layouts.

How is On-Die Termination (ODT) controlled on the W9725G6KB-25?

ODT is controlled by the dedicated ODT input ball (J9), which enables internal termination resistors when driven HIGH. Its behavior is configured via EMR(1), where ODT resistance values (75 Ω, 150 Ω, or off) are selected. ODT must be enabled before burst operations begin and remains active until disabled or device enters power-down mode.

What is the purpose of the VREF pin on the W9725G6KB-25?

The VREF pin (J2) provides the reference voltage for all address, command, and control input receivers. It must be maintained at VDDQ/2 ±300 mV during operation and ramp-up. Proper VREF stability is critical for reliable command decoding and prevents false triggering of CS, RAS, CAS, or WE signals under noise or voltage fluctuation.

Can the W9725G6KB-25 operate with CAS Latency 3?

Yes, the W9725G6KB-25 supports CAS Latency 3 at DDR2-800 speed (tCK ≥ 5 ns), as confirmed in its KEY PARAMETERS table. However, CL=3 requires stricter timing margins on tRCD (≥12.5 ns) and tRP (≥12.5 ns), and is only guaranteed within the specified operating conditions - not at maximum frequency or extended temperature.