Winbond Electronics Corporation W631GU8KB-15

Overview

W631GU8KB-15 from Winbond is a 1 Gb (128 MB) DDR3L SDRAM organized as 16M × 8 banks × 8 bits, operating at 1.35 V nominal supply with DDR3L-1333 speed grade (9-9-9 CL-tRCD-tRP), 667 MHz clock frequency, and -40°C to +95°C industrial temperature range. It delivers 1333 Mb/s/pin data transfer rate and supports on-die termination, ZQ calibration, and programmable CAS Write Latency for embedded computing and networking memory subsystems.

For engineers reviewing the W631GU8KB-15 datasheet, W631GU8KB-15 pinout, W631GU8KB-15 application, or W631GU8KB-15 equivalent, key selection considerations include its DDR3L-1333 timing compliance, 78-ball WBGA package, 1.35 V operation with 1.5 V backward compatibility, industrial temperature support, and support for dynamic ODT, write leveling, and partial array self-refresh.

Technical Context

This DDR3L SDRAM implements an 8-bit prefetch architecture with eight internal banks enabling concurrent access, differential CK/CK# and DQS/DQS# signaling, and DLL-based alignment of data and strobes to clock edges. It supports posted CAS with additive latency (AL = 0, CL−1, CL−2), auto-precharge, and burst lengths of 8 or 4 via mode register or on-the-fly control.

Functional operation includes asynchronous RESET# for power-up initialization, ZQ calibration using external 240 Ω resistor for output driver and ODT impedance tuning, and multi-purpose register (MPR) readout for system-level timing calibration. The device supports both synchronous and dynamic ODT modes, with programmable RTT values and write-leveling capability for high-speed signal integrity.

Key Specifications

Pinout & Package

W631GU8KB-15 is packaged in a 78-ball Wafer-Level Ball Grid Array (WBGA) measuring 8 mm × 10.5 mm with 0.8 mm ball pitch. The package uses lead-free, RoHS-compliant materials and supports standard reflow soldering profiles.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DDR3L SDRAM applications.

Compared with MT41K128M8XX-125:J and IS43TR16128B-125KBL, the W631GU8KB-15 offers native 1.35 V operation with guaranteed 95°C case temperature support in a compact 78-ball WBGA, making it optimal for space-constrained industrial and medical edge devices where thermal headroom and power efficiency are critical.

Availability

W631GU8KB-15 is available at Aetrix Electronics and suitable for networking equipment, industrial HMI, medical imaging devices, and edge AI gateways requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for W631GU8KB-15 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, flash, and logic ICs, with over 30 years of DRAM design heritage and JEDEC-compliant product development.

The W631GU8KB-15 belongs to Winbond's DDR3L SDRAM product line, engineered specifically for industrial, medical, and networking applications demanding extended temperature operation, low-voltage efficiency, and robust signal integrity features like write leveling and dynamic ODT.

FAQ

What is the maximum supported CAS Latency for W631GU8KB-15 at DDR3L-1333 speed?

The W631GU8KB-15 supports CAS Latency (CL) settings of 6, 7, 8, 9, 10, and 11 at DDR3L-1333 speed. Its default and fully characterized CL is 9, matching the 9-9-9 timing bin. CL=7 and CL=11 are optional and require SPD programming to enforce tAA/tRCD/tRP minima of 13.125 ns per JEDEC specification.

Does W631GU8KB-15 support true 1.35 V-only operation, or does it require 1.5 V for initialization?

W631GU8KB-15 supports true 1.35 V-only operation across its full industrial temperature range. It is not required to initialize at 1.5 V. The device complies with DDR3L specifications and includes backward compatibility circuitry that allows seamless operation at either 1.35 V (1.283–1.45 V) or 1.5 V (1.425–1.575 V), with no hardware or firmware changes needed.

Can W631GU8KB-15 be used in place of standard DDR3 (1.5 V) SDRAM without redesigning the power delivery network?

Yes - W631GU8KB-15 is backward compatible with 1.5 V DDR3 systems. Its VDD/VDDQ pins accept 1.5 V ± 0.075 V, and all AC/DC timing parameters meet JEDEC DDR3 standards at that voltage. No changes to the power delivery network are required, though VREFCA and VREFDQ must be set to 0.75 V (not 0.675 V) when operating at 1.5 V.

What is the function of the ZQ pin on W631GU8KB-15, and what external component is required?

The ZQ pin on W631GU8KB-15 serves as the calibration reference for output driver strength and on-die termination (ODT) impedance. It must be connected to a single 240 Ω ±1 % resistor tied to ground. This external resistor enables factory-trimmed 34 Ω output drivers and programmable ODT values (Rtt_Nom = 120 Ω, 60 Ω, 40 Ω) with <±3 % variation across voltage and temperature.

Is write leveling supported on W631GU8KB-15, and how is it enabled?

Yes, write leveling is fully supported on W631GU8KB-15. It is enabled by setting MR1[A8] = 1 and entering write leveling mode via MRS command. The DRAM responds with a predefined MPR pattern on DQ lines synchronized to DQS, allowing the memory controller to adjust per-lane DQS delay until edge alignment is achieved. Exit is performed by issuing a MRS command with MR1[A8] = 0.