Winbond Electronics Corporation W955K8MBYA5I

Overview

W955K8MBYA5I from Winbond Electronics is a 32Mb HyperRAM device implementing the HyperBus DDR interface for high-throughput, low-pin-count memory expansion in embedded systems. It operates at 1.8V, supports up to 200MHz clock frequency (400 MT/s), and uses an 8-bit bidirectional DQ bus with RWDS strobe/mask signaling. It targets graphics buffer, firmware code execution, and real-time data logging in microcontroller-based edge devices.

For engineers reviewing the W955K8MBYA5I datasheet, W955K8MBYA5I pinout, W955K8MBYA5I application, or W955K8MBYA5I equivalent, key selection criteria include its 24-ball TFBGA package, configurable burst modes (wrapped/linear/hybrid), hybrid sleep and deep power-down power states, and support for partial array refresh in temperature-constrained industrial environments.

Technical Context

The W955K8MBYA5I implements a DDR HyperBus interface with differential (CK/CK#) or single-ended (CK) clocking, using RWDS as a bidirectional strobe/mask signal synchronized to read/write data edges or center-aligned to clock edges respectively. Its command-address protocol encodes R/W#, address space (memory/register), and burst type in CA[47:45], enabling dynamic transaction control without dedicated control lines.

Internally, it employs row/column decoding with half-page addressing (16-byte granularity), supports linear burst with automatic next-row prefetch for sustained 400 MB/s throughput, and provides two configuration registers for latency tuning, drive strength, refresh mode (full/partial), and power state behavior (hybrid sleep, deep power down).

Key Specifications

Pinout & Package

W955K8MBYA5I is housed in a 24-ball Thin Fine-Pitch Ball Grid Array (TFBGA) package with 5×5 mm footprint and 0.8 mm ball pitch. The package supports automated assembly and thermal dissipation suitable for space-constrained industrial PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar HyperRAM interface applications.

Compared with W955K8MBYA5I, W956K8MBYA5I offers double capacity in identical form factor and timing, while IS66WV51216EBLL-100BLI demands more PCB area, higher pin count, and lacks dynamic power management - making W955K8MBYA5I optimal for new designs prioritizing integration and energy efficiency.

Availability

W955K8MBYA5I is available at Aetrix Electronics and suitable for graphics frame buffer, firmware code execution, and real-time data logging applications requiring stable component supply, industrial temperature support, and long-term lifecycle assurance.

Supply support for W955K8MBYA5I 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 SPI NOR/NAND, RAM, and interface-optimized memories.

The HyperRAM product line was designed to replace parallel NOR/PSRAM in MCU-based systems by delivering DDR bandwidth with minimal pin count and integrated power management for battery-powered and thermally constrained applications.

FAQ

What is the maximum data throughput achievable with the W955K8MBYA5I?

The W955K8MBYA5I achieves up to 400 MB/s sustained throughput using its 8-bit HyperBus DDR interface at 200MHz (8 bits × 2 data edges per clock × 200 MHz). This assumes linear burst mode with continuous CS# assertion and no inter-burst gaps. Real-world throughput depends on host controller latency, burst length configuration, and refresh overhead - but the architecture eliminates wait states typical of parallel interfaces. W955K8MBYA5I delivers this performance with only 11 signal pins (including power), significantly reducing routing complexity compared to traditional SDRAM.

Does the W955K8MBYA5I support execute-in-place (XIP) operation?

Yes, the W955K8MBYA5I supports execute-in-place (XIP) operation through its HyperBus interface, allowing microcontrollers to fetch instructions directly from the memory array without loading into internal RAM. This capability relies on predictable read latency (configurable via Configuration Register 0) and linear burst support for sequential instruction flow. W955K8MBYA5I's RWDS-based latency signaling and prefetch-optimized row access ensure deterministic timing for XIP - critical for real-time firmware execution in automotive and industrial control applications.

How does the RWDS pin function during read versus write operations in the W955K8MBYA5I?

In the W955K8MBYA5I, RWDS serves three distinct roles: during Command/Address (CA) phase, it outputs high to indicate additional initial latency is needed; during read data transfer, it acts as an edge-aligned read data strobe synchronized to DQ transitions; during write data transfer, it functions as a byte-level write mask (high = masked, low = written). This multifunctionality eliminates separate RD/WR and strobe signals. W955K8MBYA5I's RWDS behavior is fully compliant with HyperBus specification v2.0 and requires no external logic - simplifying host interface design while maintaining precise timing control.

What power-saving modes are available on the W955K8MBYA5I and how are they entered?

The W955K8MBYA5I supports Hybrid Sleep and Deep Power Down (DPD) modes, both entered via HyperBus register writes to Configuration Register 0 and 1. Hybrid Sleep reduces ICC to ~150 µA while retaining memory contents and allowing fast wake-up (<1 µs); DPD lowers ICC to <10 µA but requires full reinitialization upon exit. Entry is controlled by setting specific bit fields (e.g., CR0[23] for DPD), not hardware pins - enabling software-defined power policy. W955K8MBYA5I's power states are especially valuable in battery-operated edge nodes where duty-cycled sensing must minimize average current draw without losing volatile context.

Can the W955K8MBYA5I be used with a single-ended clock instead of differential clocking?

Yes, the W955K8MBYA5I fully supports single-ended clock operation using only the CK pin, with CK# left unconnected or tied to VSS. The device detects clock mode automatically: when CK# is inactive (not toggling), it defaults to single-ended mode and ignores CK# transitions. This flexibility allows designers to avoid differential routing complexity and associated PCB cost in cost-sensitive applications. W955K8MBYA5I maintains full 200MHz operation and timing compliance in both modes - verified across –40°C to +85°C - making it adaptable to diverse MCU and FPGA interface capabilities.