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Microchip Technology AT29C256-90JI-T
- Part No.:
- AT29C256-90JI-T
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-90JI-T.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,205
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Product details
Overview
AT29C256-90JI-T from Atmel is a 256 Kbit (32K × 8) 5V-only Flash memory IC used for nonvolatile program/data storage in embedded microcontroller systems, industrial controllers, and legacy BIOS modules. It delivers 90 ns read access time, supports page programming of 64-byte blocks in 10 ms, and operates across -40°C to +85°C with CMOS/TTL-compatible I/O.
For engineers reviewing the AT29C256-90JI-T datasheet, AT29C256-90JI-T pinout, AT29C256-90JI-T application, or AT29C256-90JI-T equivalent, key selection criteria include its 5V-only reprogramming architecture, hardware/software data protection, DATA polling and toggle-bit program status detection, and PLCC-32 packaging for through-hole industrial board designs.
Technical Context
The AT29C256-90JI-T implements a page-based Flash architecture where 64-byte pages are erased and programmed in a single internal cycle using on-chip timing control. Its dual-line chip enable (CE) and output enable (OE) logic enables flexible bus interfacing without contention, while WE-controlled byte loading allows sequential or non-sequential address/data latching during programming.
Hardware data protection includes VCC sense (<3.8 V inhibits programming), 5 ms power-on delay, and noise filtering (<15 ns pulses ignored); software protection uses three-step command sequences (e.g., AAh/55h/A0h) to enable/disable write access. Both mechanisms coexist and persist across power cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 256 Kbit (32,768 × 8), directly replaceable for 27C256 EPROMs in legacy 8-bit systems |
| Read Access Time | 90 ns max - ensures compatibility with 10 MHz Z80/8051 bus timing without wait states |
| Page Program Time | 10 ms - enables rapid field updates of firmware segments without full-chip erase overhead |
| Endurance | >10,000 write/erase cycles per sector - supports long-term logging or configuration storage |
| Supply Voltage | 5 V ± 10% - eliminates need for dedicated programming voltage rails in system design |
| Standby Current | 300 µA CMOS - enables low-power retention in battery-backed industrial controllers |
| Operating Temp | -40°C to +85°C - qualified for industrial-grade PLCs, motor drives, and instrumentation |
Pinout & Package
AT29C256-90JI-T is packaged in a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32), pin-compatible with industry-standard 32J footprint. Pins 1 and 17 are No Connect (NC) and must remain unconnected per datasheet specification.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page address during programming |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit data path; I/O7 provides DATA polling status, I/O6 toggles during program/erase |
| CE | Chip Enable | Active-low device select; when high, forces outputs to high-impedance regardless of OE state |
| OE | Output Enable | Active-low read control; used with CE for bus contention management in multi-device systems |
| WE | Write Enable | Active-low programming control; initiates byte load or page program when CE low and OE high |
| VCC | Power Supply | +5 V ± 10% main supply; powers core logic and I/O buffers |
| GND | Ground Reference | Signal and power return; decoupling capacitor required within 10 mm of VCC pin |
| NC (Pins 1, 17) | No Connect | Physically present but internally unconnected; must be left floating or tied to ground per layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| 5V-only reprogramming | Eliminates need for +12 V programming supplies, simplifying power architecture in cost-sensitive industrial designs |
| Internal page latches | 64-byte data/address latching frees external bus during 10 ms internal program cycle, enabling concurrent CPU operations |
| DATA polling & toggle bit | Real-time program status via I/O7 complement or I/O6 toggling - no external timers or interrupts required for completion detection |
| Dual data protection | Hardware (VCC sense, noise filter) and software (3-step command lock) prevent accidental writes during brown-out or EMI events |
| Software product identification | Manufacturer code (1Fh) and device code (DCh) readable via 3-byte command sequence - enables automated BOM verification |
Applications
| Industrial PLC Firmware Storage | Legacy BIOS/Boot Code Retention |
|---|---|
Use Scenario: Storing ladder logic programs and I/O configuration tables in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile boot memory holding firmware executed at power-up; accessed as memory-mapped device via 8-bit parallel bus. Use Value: 90 ns read speed meets real-time scan cycle timing; -40°C to +85°C rating ensures reliability in unconditioned control cabinets. | Use Scenario: Holding POST routines and hardware initialization code in x86-based industrial motherboards where EEPROM capacity is insufficient. IC Role / Device Role / Timing Role: Drop-in replacement for 27C256 EPROMs; emulates read behavior of static RAM during execution. Use Value: 5V-only reprogramming allows in-system firmware updates without UV erasers or socket programming fixtures. |
| Embedded Instrumentation Data Logging | Motor Drive Parameter Configuration |
Use Scenario: Recording calibration coefficients, fault history, and sensor offset values in handheld test equipment with infrequent write cycles. IC Role / Device Role / Timing Role: Configuration memory mapped into microcontroller's data space; written only during service mode or calibration procedures. Use Value: >10,000 endurance cycles exceed lifetime requirements; 300 µA standby current extends battery life in portable units. | Use Scenario: Storing torque curves, PID tuning parameters, and safety thresholds in variable-frequency drives operating in harsh electrical environments. IC Role / Device Role / Timing Role: Nonvolatile parameter store accessed by drive MCU during startup and runtime; protected against spurious writes via hardware/software locks. Use Value: VCC sense and noise filtering prevent corruption during line transients; software protection prevents unauthorized parameter changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Flash memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-90JC | Same die, PLCC-32 package but commercial temperature range (0°C to 70°C) | Not rated for industrial ambient conditions; unsuitable for enclosures without thermal management | Select only for cost-sensitive commercial products with controlled environments |
| AM29LV256M-90EC | 3.3 V core with 5 V I/O tolerant; 90 ns read; 100,000 endurance cycles | Requires level-shifting for pure 5 V systems; higher endurance but different command set and protection scheme | Choose for new 3.3 V designs needing longer lifecycle; not drop-in compatible |
Compared with AT29C256-90JI-T, AT29C256-90JC lacks industrial temperature qualification, while AM29LV256M-90EC introduces voltage-level complexity and non-identical programming protocols - both require schematic and firmware validation before substitution.
Availability
AT29C256-90JI-T is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy BIOS/Boot Code retention, and embedded instrumentation data logging requiring stable component supply over extended production lifecycles.
Supply support for AT29C256-90JI-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
Atmel Corporation (now part of Microchip Technology) is a semiconductor manufacturer specializing in microcontrollers, Flash memory, and secure authentication devices.
The AT29C256 product line was designed for 5V embedded systems requiring in-system reprogrammability without high-voltage programming infrastructure - targeting industrial control, telecommunications infrastructure, and legacy computing platforms.
FAQ
What is the maximum operating temperature range for the AT29C256-90JI-T?
The AT29C256-90JI-T is rated for industrial temperature operation from -40°C to +85°C. This specification is guaranteed per the ordering code suffix "I" and validated across AC/DC parametric testing. The "JI" designation confirms the PLCC-32 package and industrial temperature grade, making AT29C256-90JI-T suitable for deployment in uncontrolled ambient environments such as factory floors or outdoor enclosures.
Does the AT29C256-90JI-T require a high-voltage programming supply?
No, the AT29C256-90JI-T operates with 5 V ± 10% only for both read and program/erase functions. It does not require +12 V or other elevated programming voltages. All reprogramming commands are issued using standard 5 V logic levels, and internal charge pumps generate necessary high-voltage potentials. This eliminates external HV circuitry and simplifies system design - a defining feature of the AT29C256-90JI-T architecture.
How is program completion detected on the AT29C256-90JI-T?
Program completion on the AT29C256-90JI-T is detected using either DATA polling on I/O7 (complement of loaded data until completion) or the toggle-bit method on I/O6 (repeated toggling until stable). Both methods are supported simultaneously and require no external components. The AT29C256-90JI-T datasheet specifies that polling may begin at any time during the 10 ms internal program cycle, enabling efficient CPU utilization without fixed delays.
Can the AT29C256-90JI-T be used as a direct replacement for the 27C256 EPROM?
Yes, the AT29C256-90JI-T is pin- and function-compatible with the 27C256 EPROM in read mode and shares identical 32K × 8 organization and 5 V operation. However, AT29C256-90JI-T requires specific software command sequences for programming and includes hardware write protection - unlike one-time-programmable EPROMs. System firmware must implement page-load protocols and status polling to use AT29C256-90JI-T as a true in-system reprogrammable replacement.
What package type does the AT29C256-90JI-T use, and are there NC pins?
The AT29C256-90JI-T uses a 32-lead Plastic J-Leaded Chip Carrier (PLCC-32) package, indicated by the "J" in the ordering code. Pins 1 and 17 are designated as No Connect (NC) and must remain unconnected in PCB layout - this is explicitly documented in the Atmel datasheet and verified in the PLCC mechanical drawing. Connecting these pins may cause functional or reliability issues.
AT29C256-90JI-T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- FLASH
- Technology:
- FLASH
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 90 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C256-90JI-T FAQ
1.How can I place an order for AT29C256-90JI-T through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-90JI-T on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AT29C256-90JI-T reliable?
The price and inventory of AT29C256-90JI-T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-90JI-T is usually 5 days.
3.What payment methods are accepted for AT29C256-90JI-T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-90JI-T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-90JI-T?
AT29C256-90JI-T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-90JI-T order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AT29C256-90JI-T?
For technical support, including AT29C256-90JI-T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-90JI-T requirements.
6.How does Aetrix verify that AT29C256-90JI-T is sourced from the original manufacturer or authorized distributors?
All AT29C256-90JI-T products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AT29C256-90JI-T meets industry standards.
7.What is the process for return or replacement of AT29C256-90JI-T?
All AT29C256-90JI-T units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-90JI-T, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AT29C256-90JI-T part is unused and in its original packaging.
Return procedure for AT29C256-90JI-T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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