Microchip Technology AT29BV040A-25TC

Overview

AT29BV040A-25TC from Atmel is a 4-megabit (512K × 8) single-supply 2.7V–3.6V Flash memory IC used for nonvolatile code and data storage in embedded systems. It features 200 ns read access time, 20 ms max sector program cycle, 10,000 write/erase endurance, software data protection, and two 16K-byte boot blocks with independent programming lockout - deployed in industrial control firmware storage.

For engineers reviewing the AT29BV040A-25TC datasheet, AT29BV040A-25TC pinout, AT29BV040A-25TC application, or AT29BV040A-25TC equivalent, key selection considerations include sector-based reprogrammability, CMOS/TTL-compatible I/O, boot block lockout for secure bootloader storage, and TSOP-32 packaging for space-constrained PCB layouts.

Technical Context

The AT29BV040A-25TC operates as a parallel-interface Flash memory with EPROM-like read behavior: CE and OE low + WE high enables output drive; bus contention is prevented via dual-line chip/output enable control. Sector programming uses internal latches to capture 256 bytes at microprocessor speed before automatic erase-and-program execution.

It implements dual hardware and software data protection: VCC sense (<1.8V inhibits programming), 10 ms power-on delay, noise filtering (<15 ns pulses ignored), and mandatory three-byte command sequence (5555h/2AAAh/5555h) to enable writes. Boot block lockout requires a seven-command algorithm and disables chip erase once activated.

Key Specifications

Pinout & Package

AT29BV040A-25TC is housed in a 32-lead Thin Small Outline Package (TSOP Type I, 8 × 20 mm), JEDEC MO-142 BD compliant, with 0.5 mm lead pitch and 0.10 mm max coplanarity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SST39VF400A-70-4C-NHE and MX29LV400CBTI-70G, the AT29BV040A-25TC uniquely delivers 256-byte sector erasure with independent boot block lockout in a compact 32-pin TSOP, making it optimal for space-constrained designs requiring secure, granular firmware updates.

Availability

AT29BV040A-25TC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, medical device configuration memory, and automotive body control module applications requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AT29BV040A-25TC 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

Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, Flash memory, and secure authentication devices.

The AT29BV040A-25TC belongs to Atmel's Battery-Voltage™ Flash memory product line, designed specifically for reliable, low-voltage in-system reprogrammability in embedded systems with constrained power and physical space.

FAQ

What is the maximum read access time specified for the AT29BV040A-25TC?

The AT29BV040A-25TC has a maximum read access time of 250 ns, as confirmed by its ordering code suffix "-25". This value applies across the commercial temperature range (0°C to +70°C) and defines the worst-case delay from address valid to valid data on I/O0–I/O7 when CE and OE are asserted. The AT29BV040A-25TC achieves this timing at VCC = 2.7V–3.6V with standard TTL/CMOS load conditions.

Does the AT29BV040A-25TC support hardware reset or power-on initialization sequences?

The AT29BV040A-25TC does not include an internal hardware reset circuit. After power application, the system must wait ≥20 ms before initiating any operational mode, as specified in the datasheet. This delay ensures VCC stabilization and internal circuit readiness. The AT29BV040A-25TC relies on external controller sequencing - no dedicated reset pin or POR logic is integrated.

How does software data protection work on the AT29BV040A-25TC?

Software data protection on the AT29BV040A-25TC requires a precise three-byte command sequence: write 0xAA to address 0x5555, then 0x55 to address 0x2AAA, then 0xA0 to address 0x5555. Only after this sequence is completed can subsequent byte loads initiate programming. The AT29BV040A-25TC ignores all write attempts lacking this sequence, preventing accidental writes during power transitions or noise events.

Can the AT29BV040A-25TC be used with a 5V microcontroller interface?

Yes - the AT29BV040A-25TC accepts address and control inputs (A0–A18, CE, OE, WE) at voltages up to 5.5V, independent of its 2.7V–3.6V VCC supply. This allows direct connection to 5V microcontrollers without level-shifting circuitry. However, I/O0–I/O7 pins are limited to 0–VCC+0.6V, so bidirectional data lines require level translation if the MCU operates at 5V.

What happens to the boot block lockout feature once enabled on the AT29BV040A-25TC?

Once enabled via the seven-command algorithm, the boot block lockout feature on the AT29BV040A-25TC becomes permanent and irreversible for that block - neither erasure nor reprogramming is possible. Enabling lockout on either 16K-byte boot block also disables the entire-chip erase function. The AT29BV040A-25TC provides software detection (read 0x00002h or 0x7FFF2h) to verify lockout status before committing to the algorithm.