Winbond Electronics Corporation W9725G8KB-18

Overview

W9725G8KB-18 from Winbond Electronics is a 256M-bit DDR2 SDRAM organized as 8,388,608 words × 4 banks × 8 bits, operating at 1.8 V ± 0.1 V with DDR2-1066 (7-7-7) timing, CAS latency 3–7, and burst lengths of 4 or 8. It serves as main system memory in embedded controllers and industrial SoC platforms requiring synchronous, high-bandwidth data buffering.

For engineers reviewing the W9725G8KB-18 datasheet, W9725G8KB-18 pinout, W9725G8KB-18 application, or W9725G8KB-18 equivalent, key selection criteria include its SSTL_18 interface compliance, on-die termination (ODT), OCD impedance calibration, differential clock (CLK/CLK) and data strobe (DQS/DQS) support, and -40°C to +85°C industrial temperature rating.

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 I/O referenced to both edges of DQS. It supports posted CAS (AL = 0–2), auto-precharge, and programmable write latency (WL = RL − 1).

Functional operation relies on four independent banks, mode register (MR) and extended mode registers (EMR1–EMR3) for configuration of ODT, OCD, DLL enable/disable, RDQS, and additive latency. Initialization requires strict power-up sequencing including EMRS commands to EMR(2), EMR(3), and EMR(1) for DLL enable before MRS programming.

Key Specifications

Pinout & Package

Packaged in RoHS-compliant, lead-free WBGA-60 (8 mm × 12.5 mm) with 0.8 mm ball pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MT47H64M4BP-37E and IS42S16400F-6BL, the W9725G8KB-18 delivers superior signal integrity via OCD calibration and flexible ODT control, supports higher data rates with guaranteed DDR2-1066 timing, and provides industrial-grade thermal reliability in compact WBGA packaging - critical for space-constrained, thermally demanding embedded systems.

Availability

W9725G8KB-18 is available at Aetrix Electronics and suitable for industrial HMI controllers, network infrastructure packet buffers, medical imaging frame stores, and automotive ADAS video preprocessors requiring stable component supply across multi-year production cycles.

Supply support for W9725G8KB-18 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 DDR SDRAM for industrial, automotive, and communications markets.

The W9725G8KB-18 belongs to Winbond's industrial-grade DDR2 SDRAM product line, designed specifically for reliable, long-lifecycle operation in temperature-stressed embedded systems with stringent signal integrity and power management requirements.

FAQ

What is the maximum data rate supported by the W9725G8KB-18?

The W9725G8KB-18 supports DDR2-1066 operation with a minimum clock period (tCK) of 1.875 ns at CAS Latency 7, delivering up to 1066 Mb/sec per pin. This speed grade is validated under industrial temperature conditions (0°C to 85°C) and requires adherence to specified AC timing parameters including tRCD ≥ 13.125 ns and tRP ≥ 13.125 ns.

Does the W9725G8KB-18 support on-die termination (ODT)?

Yes, the W9725G8KB-18 supports programmable on-die termination via the ODT pin and extended mode register EMR(1). When ODT is asserted HIGH, internal termination resistors are enabled on DQ and DQS lines to suppress reflections, eliminating the need for external parallel termination and improving signal integrity in point-to-point or fly-by topologies.

How is the W9725G8KB-18 initialized after power-up?

The W9725G8KB-18 requires a strict 13-step initialization sequence: stable power ramp, 200 µs clock stabilization, CKE assertion, precharge all, three EMRS commands (to EMR(2), EMR(3), and EMR(1) for DLL enable), DLL reset, second precharge all, two auto-refresh commands, final MRS, and OCD calibration. Skipping any step may result in undefined behavior or initialization failure.

What package type and ball count does the W9725G8KB-18 use?

The W9725G8KB-18 uses a RoHS-compliant, lead-free WBGA-60 package measuring 8 mm × 12.5 mm with 0.8 mm ball pitch. Its 60-ball layout includes dedicated VDDQ/VSSQ planes for I/O noise isolation, differential clock (CLK/CLK) and strobe (DQS/DQS) pairs, and NC balls for mechanical reinforcement and thermal relief.

Can the W9725G8KB-18 operate with CAS Latency 3?

Yes, the W9725G8KB-18 supports CAS Latency 3 at lower frequencies (e.g., DDR2-667 or DDR2-800), with tCK min = 5 ns. At DDR2-1066 speed, CL=3 is not supported; the minimum valid CL for -18 speed grade is CL=5 (tCK min = 3 nS) or CL=7 (tCK min = 1.875 nS), per the device's AC timing specifications in the official datasheet.