Winbond Electronics Corporation W39V040FAPZ

Overview

W39V040FAPZ from Winbond is a 4-Mbit (512K × 8) CMOS flash memory with dual-interface support (Programmer bus and Intel Firmware Hub), single 3.3 V operation, 11 ns read access time, and hardware boot-block protection via #TBL/#WP pins. It delivers fast sector/page erase (≤25 ms max) and byte-program (35 μs typ.) for embedded BIOS and firmware storage in legacy x86 platforms.

For engineers reviewing the W39V040FAPZ datasheet, W39V040FAPZ pinout, W39V040FAPZ application, or W39V040FAPZ equivalent, key selection criteria include FWH interface compliance, top-boot block lockout capability, hardware write protection pin behavior, and PLCC-32 package compatibility with legacy socketed designs.

Technical Context

The W39V040FAPZ implements a dual-mode interface architecture: Programmer mode uses multiplexed A[10:0] address inputs with #OE/#WE control, while FWH mode operates synchronously via CLK and FWH[3:0]/FWH4 signals per Intel FWH specification. Mode selection is determined by the IC pin state at power-up or reset.

It features eight uniform 64 KB sectors, each subdivided into sixteen 4 KB pages, enabling flexible erase granularity. Hardware protection is implemented through dedicated #TBL (top boot block lock) and #WP (write protect) pins that override software lock registers when asserted low, ensuring fail-safe firmware integrity during power transitions.

Key Specifications

Pinout & Package

W39V040FAPZ is packaged in 32-lead PLCC (Plastic Leaded Chip Carrier) with 1.27 mm pitch, compatible with standard ZIF sockets used in BIOS programming and motherboard repair workflows.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar flash memory applications.

Compared with W39V040BAPZ, the W39V040FAPZ adds FWH interface support and boot block lockout detection via FGPI pins - essential for secure, chipset-native BIOS operation. Against MX29LV400CBTI-70G, it trades slower access time for deterministic hardware protection and legacy platform qualification.

Availability

W39V040FAPZ is available at Aetrix Electronics and suitable for legacy PC motherboard repair, industrial control firmware updates, and embedded system recovery image storage requiring stable component supply across extended production lifecycles.

Supply support for W39V040FAPZ 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 manufacturer specializing in specialty memory, flash, and logic devices for computing and embedded markets.

The W39V040FAPZ belongs to Winbond's W39V family of FWH-compatible flash memories, designed specifically for BIOS/firmware storage in x86 platforms requiring Intel chipset integration and hardware-level boot security.

FAQ

What interface modes does the W39V040FAPZ support, and how is mode selection controlled?

The W39V040FAPZ supports two interface modes: Programmer bus mode and Intel Firmware Hub (FWH) mode. Mode selection is determined solely by the logic level on the IC pin at power-up or after #RESET assertion: high (VDD) selects Programmer mode, while low or floating selects FWH mode. This hardwired selection ensures deterministic initialization without software configuration overhead. The W39V040FAPZ must be powered in the intended mode - dynamic switching between modes is not supported during operation.

How does hardware protection via #TBL and #WP pins interact with software block locking registers in the W39V040FAPZ?

In the W39V040FAPZ, hardware protection takes absolute precedence: when #TBL is pulled low, the top boot block (16 KB or 64 KB) is locked regardless of software register settings; when #WP is pulled low, all non-boot sectors are write-protected irrespective of BLR register states. The W39V040FAPZ datasheet explicitly states that hardware protection overrides software lock bits. Reading BLR registers will not reflect the effective protection state - only status bits DQ2 (for #TBL) and DQ3 (for #WP) at address 7FFF2 indicate actual pin states.

What is the purpose and behavior of the FGPI[4:0] pins on the W39V040FAPZ?

The FGPI[4:0] pins on the W39V040FAPZ are General Purpose Input pins readable via the GPI register at memory address FFBC0100h. They provide five user-configurable input signals that can be sampled by host firmware to detect board-level conditions (e.g., jumper settings, revision ID, or debug mode). Unlike control pins such as #TBL or #WP, FGPI pins have no effect on memory operation - they serve purely as status inputs. The W39V040FAPZ does not drive these pins; they must be externally pulled up or down to define logic levels.

Can the W39V040FAPZ be programmed using standard EPROM programmers, and what interface mode is required?

Yes, the W39V040FAPZ can be programmed using standard EPROM programmers, but only when operating in Programmer interface mode - selected by pulling the IC pin high at power-up. In this mode, the device presents conventional parallel flash behavior with multiplexed address inputs (A[10:0]) and discrete #OE/#WE controls. FWH mode is incompatible with generic EPROM programmers because it requires synchronous CLK-driven signaling and FWH[3:0] multiplexing. The W39V040FAPZ datasheet confirms EPROM programmer support explicitly for Programmer mode operation.

What is the function of the "Lock Down" bit in the W39V040FAPZ block locking registers, and how is it cleared?

The Lock Down bit (BIT 1) in each W39V040FAPZ block locking register (BLR0–BLR7) is a one-time-programmable flag that permanently disables further modification of the Read Lock and Write Lock bits for that sector. Once set, it cannot be cleared by software - only a hardware reset via #RESET or #INIT de-assertion clears the Lock Down bit, returning the register to modifiable state. This feature ensures irreversible lockdown of critical firmware partitions after final validation. The W39V040FAPZ datasheet specifies that Lock Down is cleared only on power-on reset or active-low #RESET assertion.