Winbond Electronics Corporation W9725G6KB-18

Overview

W9725G6KB-18 from Winbond Electronics is a 256M-bit DDR2 SDRAM organized as 4M words × 4 banks × 16 bits, operating at 1.8 V ± 0.1 V with DDR2-1066 (7-7-7) timing and CAS latency options of 3–7. It supports differential clock inputs (CLK/CLK), bi-directional DQS-strobed I/O, and on-die termination for high-speed memory subsystems in embedded networking and industrial control applications.

For engineers reviewing the W9725G6KB-18 datasheet, W9725G6KB-18 pinout, W9725G6KB-18 application, or W9725G6KB-18 equivalent, key selection criteria include its -18 speed grade compliance with DDR2-1066, 84-ball WBGA package, SSTL_18 interface compatibility, OCD impedance calibration support, and self-refresh current ≤6 mA at TCASE ≤ 85°C.

Technical Context

This DDR2 SDRAM implements a double-data-rate architecture synchronized to differential clock edges, with DLL-aligned DQ/DQS timing and source-synchronous data capture. Its command decoder interprets RAS/CAS/WE/CS on each CLK rising edge, while read/write operations use programmable additive latency (AL = 0–2) and burst lengths of 4 or 8.

The device integrates four independent banks with shared address/control logic, on-die termination (ODT) controllable via dedicated ODT pin, and off-chip driver (OCD) impedance adjustment via EMR(1). Power management includes precharged/active power-down modes and self-refresh with IDD6 ≤6 mA.

Key Specifications

Pinout & Package

Packaged in 84-ball WBGA (8 mm × 12.5 mm, RoHS-compliant lead-free).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MT47H64M16HR-37E and IS42S16160F-6BLI, W9725G6KB-18 delivers higher bandwidth (1066 Mb/sec/pin vs. 800/667), full AL support for command pipelining, and field-programmable OCD/ODT-critical for signal-integrity-constrained designs operating near PCB trace length limits.

Availability

W9725G6KB-18 is available at Aetrix Electronics and suitable for industrial automation, network infrastructure, medical imaging, and avionics applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for W9725G6KB-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 DRAM products for industrial, automotive, and communications markets.

The W97 series DDR2 SDRAM product line is designed for cost-effective, high-reliability memory subsystems in resource-constrained embedded systems requiring DDR2-667 to DDR2-1066 performance with industrial temperature support and advanced power management.

FAQ

What is the maximum supported clock frequency for W9725G6KB-18?

The W9725G6KB-18 is rated for DDR2-1066 operation, corresponding to a minimum clock period (tCK) of 1.875 ns and a maximum clock frequency of 533 MHz. This speed grade is validated under the 7-7-7 timing bin (tRCD = tRP = tRAS = 7 cycles at 533 MHz), and requires stable 1.8 V ± 0.1 V supplies and proper DLL initialization per the power-up sequence in the datasheet. W9725G6KB-18 achieves this performance using differential clock inputs and DLL-aligned DQS timing.

Does W9725G6KB-18 support on-die termination (ODT) and how is it controlled?

Yes, W9725G6KB-18 supports on-die termination (ODT) via a dedicated ODT pin (Ball K9) that enables internal termination resistors on DQ and DQS lines when driven HIGH. ODT state is registered on the rising edge of CLK, and timing parameters such as tODT and tZQ are specified in the AC characteristics table. The ODT function is independent of mode register settings and operates in all active and standby states except self-refresh. W9725G6KB-18 uses this feature to eliminate external termination resistors and improve signal integrity in point-to-point or fly-by topologies.

What are the valid CAS latency and additive latency combinations for W9725G6KB-18?

W9725G6KB-18 supports CAS latency (CL) values of 3, 4, 5, 6, or 7, and additive latency (AL) values of 0, 1, or 2. Valid read latency (RL) combinations are RL = AL + CL, yielding RL = 3–9. For example, CL=5 with AL=2 gives RL=7, required for certain DDR2-1066 configurations. These values are programmed via the Mode Register Set (MRS) and Extended Mode Register Set (EMRS) commands during initialization. W9725G6KB-18 must be initialized with matching CL/AL settings before normal operation begins.

How does the OCD calibration feature work in W9725G6KB-18?

W9725G6KB-18 implements off-chip driver (OCD) impedance calibration through EMR(1) programming, allowing dynamic adjustment of output driver strength to match PCB trace impedance. Calibration is initiated by setting EMR(1)[A9:A7] = 111 (OCD default), then executing OCD entry with A9:A7 = 111 and exiting with A9:A7 = 000. The process adjusts pull-up/pull-down driver impedances in 10% steps between 34 Ω and 73 Ω (nominal 40 Ω). W9725G6KB-18 uses this to compensate for voltage/temperature drift and maintain signal integrity without external resistor networks.

What package type and ball pitch does W9725G6KB-18 use?

W9725G6KB-18 is packaged in an 84-ball WBGA (Wafer-Level Ball Grid Array) with dimensions of 8 mm × 12.5 mm and a ball pitch of 0.8 mm. The package uses lead-free, RoHS-compliant materials and features separate power domains (VDD/VDDL for core, VDDQ/VSSQ for I/O) to minimize noise coupling. Ball assignments follow JEDEC-standard DDR2 layouts, with dedicated VREF, ODT, and differential clock/strobe pins positioned to support controlled-impedance routing. W9725G6KB-18's WBGA footprint is optimized for compact industrial PCBs requiring high-density memory placement.