Microchip Technology AT29C257-90JC-T

Overview

AT29C257-90JC-T from Microchip Technology (formerly Atmel) is a 5-V-only, 256 Kbit (32 K × 8) in-system reprogrammable Flash PEROM with 90 ns read access time, 10 ms page program time, and CMOS standby current of 300 µA. It operates across 0°C to 70°C, uses PLCC-32 packaging, and supports hardware/software data protection for embedded firmware storage in microcontroller-based systems.

For engineers reviewing the AT29C257-90JC-T datasheet, AT29C257-90JC-T pinout, AT29C257-90JC-T application, or AT29C257-90JC-T equivalent, key selection criteria include 5 V ±10% supply compatibility, page-based programming (64-byte latch), DATA polling/toggle-bit end-of-write detection, and pin compatibility with AT29C010A/AT29C512 for memory upgrades.

Technical Context

The AT29C257-90JC-T implements a nonvolatile Flash architecture with internal address/data latches for 64-byte page loading, autonomous erase-and-program control via on-chip timer, and dual-line chip enable (CE)/output enable (OE) bus contention management. Its read interface emulates static RAM timing, while write cycles require precise WE/CE pulse sequencing within 150 µs byte-load windows.

Hardware data protection includes V_CC sense (<3.8 V inhibit), 5 ms power-on delay, and noise filtering (<15 ns pulses rejected); software protection uses three-command sequences (e.g., 5555h/2AAAh/80h) to enable/disable write locks, persisting across power cycles without reset.

Key Specifications

Pinout & Package

AT29C257-90JC-T is housed in a 32-lead Plastic Leaded Chip Carrier (PLCC) package with J-bend leads, designed for surface-mount assembly and socket-compatible replacement in legacy designs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SST39SF200A-90-4C-NHE and MX29LV256EITI-90G, the AT29C257-90JC-T uniquely delivers 5 V–only in-system programming with integrated software/hardware write protection in a drop-in PLCC-32 footprint-critical for cost-sensitive, field-upgradable commercial and industrial designs.

Availability

AT29C257-90JC-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, automotive ECU bootloader memory, and medical device configuration EEPROM requiring stable component supply and long-term lifecycle support.

Supply support for AT29C257-90JC-T 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

Microchip Technology is a global semiconductor company specializing in microcontrollers, analog components, and nonvolatile memory solutions for embedded systems.

The AT29C257-90JC-T belongs to Microchip's legacy Flash PEROM product line, engineered for reliable, in-system reprogrammable firmware storage in 5 V microcontroller applications where pin compatibility and low-power standby are critical.

FAQ

What is the maximum operating temperature range for the AT29C257-90JC-T?

The AT29C257-90JC-T is rated for commercial operation from 0°C to +70°C. Its PLCC-32 package and internal thermal design ensure stable 90 ns read timing and 10 ms page programming performance across this full range without derating. The "C" suffix in the ordering code explicitly denotes the commercial temperature grade, distinguishing it from industrial-grade variants like AT29C257-90JI-T.

Does the AT29C257-90JC-T require high-voltage programming signals?

No, the AT29C257-90JC-T uses 5-V-only reprogramming - no 12 V or other high-voltage signals are needed. All program and erase operations are initiated using standard 5 V logic levels applied to CE, WE, and address/data pins per documented command sequences (e.g., 5555h/2AAAh/80h). This eliminates external HV generators and simplifies system-level design compared to older EPROM or UV-erasable devices.

How does the AT29C257-90JC-T indicate completion of a page program cycle?

The AT29C257-90JC-T provides two hardware-supported methods: DATA polling (complement on I/O7 of last loaded byte) and Toggle Bit detection (I/O6 toggles during programming and stops when complete). Both methods allow the host controller to detect write completion without fixed delays, enabling deterministic firmware update timing. These features are fully functional during the 10 ms internal program cycle and require no additional status registers.

Is the AT29C257-90JC-T pin-compatible with other Atmel Flash devices?

Yes, the AT29C257-90JC-T is explicitly pin-compatible with AT29C010A and AT29C512 in the same PLCC-32 package. This allows direct substitution in existing PCB layouts for memory upgrades or downgrades without redesign. Pin mapping for A0–A14, CE, OE, WE, and I/O0–I/O7 is identical; NC pin placement also matches, preserving mechanical and electrical compatibility.

What is the endurance rating of the AT29C257-90JC-T, and how is it validated?

The AT29C257-90JC-T has a typical endurance rating of >10,000 write/erase cycles per sector, verified through accelerated life testing per JEDEC standards. This rating applies to any address location and reflects guaranteed performance under specified operating conditions (5 V ±10%, 0°C to +70°C). Endurance is maintained by the device's internal charge-pump and oxide stress management, independent of external voltage regulation quality.