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Microchip Technology AT29C256-20JC
- Part No.:
- AT29C256-20JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT29C256-20JC.pdf
- Description:
- IC FLASH 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,968
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Product details
Overview
AT29C256-20JC from Microchip Technology is a 256 Kbit (32K × 8) CMOS parallel EEPROM with 200 ns maximum access time, single 5V supply operation, and hardware data protection via Write Protect pin. It serves as non-volatile program/data storage in microcontroller-based systems requiring byte-level reprogrammability.
For engineers reviewing the AT29C256-20JC datasheet, AT29C256-20JC pinout, AT29C256-20JC application, or AT29C256-20JC equivalent, key selection criteria include access speed, write endurance (10,000 cycles), data retention (100 years), and compatibility with 8-bit microprocessor buses.
Technical Context
This parallel EEPROM uses a standard JEDEC-compliant 28-pin DIP package with address latch enable (ALE) and output enable (OE) control signals. It implements internal address latching and automatic write timing, eliminating external timing components.
Write operations are initiated by toggling WE while CE and OE are active low; data is latched on the falling edge of WE. The WP pin disables write commands when asserted high, providing hardware-level write protection independent of software control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports full firmware image or configuration table storage in 8-bit embedded systems. |
| Access Time | 200 ns max - enables direct interface with legacy 8051, Z80, or 68000-family microprocessors without wait states. |
| Supply Voltage | 5.0 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for voltage regulators. |
| Write Endurance | 10,000 write cycles - sufficient for field-updatable calibration data or infrequently modified system parameters. |
| Data Retention | 100 years at +25°C - ensures long-term reliability in industrial control or metering applications without battery backup. |
| Write Protection | Hardware WP pin - prevents accidental overwrites during power transitions or firmware glitches without software intervention. |
Pinout & Package
AT29C256-20JC is housed in a 28-pin plastic dual in-line package (PDIP) with 0.600-inch body width and standard through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepts full 32K memory map; compatible with 8085/8086-style address decoding. |
| Q0–Q7 | Data Outputs | 8-bit bidirectional data bus connects directly to microprocessor data lines without transceivers. |
| CE | Chip Enable | Active-low chip select enables device only when asserted; allows multi-chip memory expansion. |
| OE | Output Enable | Active-low control for data output gating; used to share data bus with other peripherals. |
| WE | Write Enable | Active-low signal initiates internal write cycle; timing controlled by device, not host processor. |
| WP | Write Protect | Active-high hardware lock disables all write operations regardless of CE/OE/WE state. |
| VCC | Power Supply | +5V supply input; decoupling capacitor required per JEDEC DIP layout guidelines. |
| GND | Ground | Signal and power reference plane; requires low-impedance connection to system ground. |
Key Features
| Feature | Design Value |
|---|---|
| Single 5V Supply Operation | Eliminates need for dual-voltage rails or charge pumps, reducing BOM count and PCB complexity in legacy designs. |
| Byte-Level Programming | Enables selective updates of individual memory locations without erasing entire sectors or devices. |
| Automatic Write Timing | Internal timers handle write pulse width and verification, freeing host processor from precise timing management. |
| Hardware Write Protection | WP pin provides fail-safe write blocking during power-on reset, brown-out, or firmware exceptions. |
| JEDEC Standard Pinout | Ensures drop-in compatibility with industry-standard 28-pin EPROM/EEPROM sockets and existing PCB layouts. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping tables and ladder logic parameters in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Non-volatile configuration memory retaining settings across power cycles and temperature extremes. Use Value: 100-year data retention and hardware WP ensure parameter integrity without battery backup or periodic refresh. | Use Scenario: Holding sensor offset/gain coefficients and regulatory compliance logs in portable diagnostic equipment. IC Role / Device Role / Timing Role: Field-updatable calibration repository accessed during device boot and maintenance mode. Use Value: Byte-level programming allows targeted updates of calibration values without rewriting firmware or risking system instability. |
| Automotive ECU Bootloader Storage | Point-of-Sale Terminal Firmware Patching |
Use Scenario: Hosting bootloader code and secure update metadata in engine control units subject to AEC-Q100 stress testing. IC Role / Device Role / Timing Role: Read-only execution memory during cold start; write-enabled only during authenticated firmware updates. Use Value: 200 ns access time meets real-time boot timing budgets; WP pin prevents corruption during vehicle ignition transients. | Use Scenario: Storing localized language packs and tax rule updates in retail terminals deployed globally. IC Role / Device Role / Timing Role: Field-serviceable firmware extension memory accessible via serial port or USB host interface. Use Value: JEDEC-standard pinout allows use of existing socketed memory carriers, minimizing service depot tooling changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT29C256-20PC | Same die, PDIP package with 0.300-inch body width instead of 0.600-inch; identical timing and electrical specs. | Requires different socket footprint; not mechanically interchangeable with AT29C256-20JC. | Select AT29C256-20PC only when board layout accommodates narrow-body DIP. |
| MX29LV256DTTC-90G | 3.3V-only operation, 90 ns access time, 1Mbit density; uses different command protocol and lacks WP pin. | Suitable for newer low-voltage designs but requires firmware rewrite and PCB redesign for voltage and interface. | Choose MX29LV256DTTC-90G only for new 3.3V designs prioritizing speed and density over legacy compatibility. |
Compared with AT29C256-20JC, AT29C256-20PC offers identical functionality in a narrower DIP package, while MX29LV256DTTC-90G delivers faster access and higher density at the cost of voltage compatibility and hardware write protection-making AT29C256-20JC optimal for 5V legacy system maintenance.
Availability
AT29C256-20JC is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and automotive electronics requiring stable component supply and long-lifecycle support.
Supply support for AT29C256-20JC 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 U.S.-based semiconductor company specializing in microcontrollers, analog devices, and non-volatile memory solutions for embedded applications.
The AT29C256-20JC belongs to Microchip's legacy parallel EEPROM product line, designed specifically for backward-compatible replacement of EPROMs and early-generation EEPROMs in 8-bit microprocessor systems.
FAQ
What is the maximum access time specification for AT29C256-20JC?
The AT29C256-20JC has a maximum access time of 200 ns at VCC = 5.0 V and TA = +25°C. This value is guaranteed across the commercial temperature range (0°C to +70°C) and ensures compatibility with microprocessors such as the Intel 8085 and Zilog Z80 that require sub-250 ns memory read cycles without wait-state insertion.
Does AT29C256-20JC support byte-level writes without sector erasure?
Yes, AT29C256-20JC supports true byte-level programming: each of the 32,768 memory locations can be written individually without erasing adjacent bytes or requiring block-level erase cycles. This capability is implemented in silicon and verified per Microchip's datasheet revision C, enabling efficient updates of configuration registers or calibration constants.
How does the Write Protect (WP) pin function on AT29C256-20JC?
The WP pin on AT29C256-20JC is an active-high hardware lock that disables all write operations-including byte programming and chip erase-regardless of CE, OE, or WE states. When WP = VCC, internal write circuitry is disabled; when WP = GND, normal write functionality resumes. This behavior is electrically enforced and requires no firmware interaction.
Is AT29C256-20JC compatible with standard 28-pin EPROM sockets?
Yes, AT29C256-20JC uses a 28-pin PDIP package with 0.600-inch body width and JEDEC-standard pinout, making it mechanically and electrically compatible with sockets designed for 27C256 EPROMs. No PCB modification is needed for direct replacement in legacy systems using UV-erasable EPROMs.
What is the data retention period for AT29C256-20JC under typical operating conditions?
AT29C256-20JC guarantees 100 years of data retention at +25°C ambient temperature. Retention decreases logarithmically with increasing junction temperature; at +85°C, retention is specified at 10 years. This specification is based on accelerated life testing per JESD22-A117 and applies to data stored after successful write verification.
AT29C256-20JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- 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:
- 200 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT29C256-20JC FAQ
1.How can I place an order for AT29C256-20JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT29C256-20JC 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 AT29C256-20JC reliable?
The price and inventory of AT29C256-20JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT29C256-20JC is usually 5 days.
3.What payment methods are accepted for AT29C256-20JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT29C256-20JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT29C256-20JC?
AT29C256-20JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT29C256-20JC 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 AT29C256-20JC?
For technical support, including AT29C256-20JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT29C256-20JC requirements.
6.How does Aetrix verify that AT29C256-20JC is sourced from the original manufacturer or authorized distributors?
All AT29C256-20JC 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 AT29C256-20JC meets industry standards.
7.What is the process for return or replacement of AT29C256-20JC?
All AT29C256-20JC units undergo pre-shipment inspection (PSI). If there is an issue with AT29C256-20JC, 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 AT29C256-20JC part is unused and in its original packaging.
Return procedure for AT29C256-20JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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