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Microchip Technology AT28C64X-25PI
- Part No.:
- AT28C64X-25PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28C64X-25PI.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,474
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Product details
Overview
AT28C64X-25PI from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 250 ns read access time, 1 ms fast byte write cycle, and industrial temperature range (–40°C to +85°C). It operates from a single 5V ±10% supply, supports READY/BUSY polling and DATA polling for write completion detection, and is used in firmware storage and configuration memory for embedded controllers.
For engineers reviewing the AT28C64X-25PI datasheet, AT28C64X-25PI pinout, AT28C64X-25PI application, or AT28C64X-25PI equivalent, key selection considerations include its self-timed write architecture, CMOS/TTL compatibility, 10⁴ write endurance, RDY/BUSY pin omission (per AT28C64X variant), and PDIP-28 industrial-grade packaging.
Technical Context
The AT28C64X-25PI implements a parallel EEPROM architecture with internal address/data latching and an autonomous control timer that manages erase-before-write sequencing without external timing components. Its dual write-detection methods-DATA polling on I/O7 and (in non-X variants) open-drain RDY/BUSY-enable flexible microprocessor interfacing.
It features VCC-sense write protection, 5 ms power-on delay before write enable, and chip clear via 12 V on OE. The device includes 32 bytes of user-accessible identification EEPROM at addresses 1FE0H–1FFFH and supports TTL/CMOS-compatible signaling with 0.45 V VOL and 2.4 V VOH under load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8 bits); sufficient for boot code, calibration tables, or device configuration in resource-constrained systems |
| Read Access Time | 250 ns max; compatible with 4 MHz Z80, 8051, and 68000-based bus cycles without wait states |
| Byte Write Time | 1 ms typical; self-timed with internal timer - no external strobe or timing logic required |
| Endurance | 10,000 write/erase cycles; validated for field-updatable firmware storage in industrial controllers |
| Data Retention | 10 years at +85°C; ensures long-term reliability in unattended embedded deployments |
| Supply Voltage | 5 V ±10%; eliminates need for dedicated voltage regulators in 5 V system rails |
| Standby Current | 100 µA (CMOS); enables low-power operation during sleep modes in battery-backed systems |
Pinout & Package
AT28C64X-25PI uses a 28-lead PDIP (Plastic Dual Inline Package), 0.600" wide, JEDEC MS-011 AB compliant. Pin 1 is NC (No Connect) per AT28C64X specification; RDY/BUSY function is omitted.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; TTL/CMOS compatible |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; supports true read/write data flow with high-impedance tri-state outputs |
| CE | Chip Enable | Active-low chip select; enables device when low and OE is low / WE is high (read) or low (write) |
| OE | Output Enable | Active-low output gate; controls data bus drivers independently of CE for bus contention management |
| WE | Write Enable | Active-low write strobe; initiates self-timed byte write on falling edge; latches address and data |
| GND | Ground Reference | Signal and power return path; decoupling capacitor placement critical near pin 14 |
| VCC | Power Supply | +5 V ±10% supply; requires local 0.1 µF ceramic bypass capacitor between pins 28 and 14 |
| NC | No Connect | Pin 1 is unconnected per AT28C64X; must remain floating - no pull-up/down or routing |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed Byte Write | Eliminates external timing circuitry; internal timer handles erase-before-write and verification autonomously |
| DATA Polling Support | I/O7 toggles complemented data during write; allows software-driven write completion detection without RDY/BUSY pin |
| VCC Sense Protection | Blocks writes if VCC drops below ~3.8 V; prevents corruption during brown-out or power ramp conditions |
| JEDEC Byte-wide Pinout | Direct drop-in replacement for SRAM and EPROM families (e.g., 2764, 6264) in existing PCB layouts |
| User Identification Area | 32-byte EEPROM block at 1FE0H–1FFFH; enables serialization, revision tracking, or calibration storage |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Memory |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed via 8-bit parallel bus during power-up and runtime reconfiguration. Use Value: Ensures parameter persistence across 100,000+ power cycles and 10-year field life without battery backup. |
Use Scenario: Holding sensor calibration coefficients and device serial numbers in portable diagnostic equipment requiring FDA-compliant traceability. IC Role / Device Role / Timing Role: Secure, tamper-resistant storage element interfaced to an 8051 microcontroller during manufacturing and service calibration. Use Value: Leverages 32-byte ID area for unique device fingerprinting and supports write-protection schemes via VCC sensing. |
| Telecom Line Card Boot Firmware | Automotive Body Control Module Settings |
Use Scenario: Hosting boot loader and initialization code for DSP-based line cards in carrier-class DSLAMs operating in controlled-temperature racks. IC Role / Device Role / Timing Role: Parallel boot memory mapped into CPU address space; read during reset vector fetch. Use Value: 250 ns access time meets timing budget for 4 MHz bus clocks; industrial temp rating ensures reliability at 70°C ambient. |
Use Scenario: Retaining seat/mirror position presets, lighting profiles, and CAN node configuration in automotive body control units exposed to under-hood thermal cycling. IC Role / Device Role / Timing Role: Configuration EEPROM accessed over microcontroller's parallel expansion bus during startup and user adjustment events. Use Value: 10⁴ endurance exceeds lifetime write cycles for user settings; 100 µA standby current minimizes parasitic drain on vehicle battery. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-25PI | Same pinout and timing, but includes functional RDY/BUSY pin (pin 1); 10⁵ endurance option available | Supports hardware-busy signaling; preferred where deterministic write latency is required | Select AT28C64B-25PI if RDY/BUSY-driven interrupt handling is needed; otherwise AT28C64X-25PI reduces BOM count by eliminating pull-up resistor |
| MX28LV640E-25P | 64 Kbit parallel EEPROM, 250 ns access, but requires 3.3 V supply and has different DC characteristics (e.g., 2 mA standby) | Not 5 V compatible; requires level-shifting in legacy 5 V systems | Choose MX28LV640E-25P only in new 3.3 V designs; AT28C64X-25PI maintains direct 5 V integration |
Compared with AT28C64B-25PI, AT28C64X-25PI trades RDY/BUSY functionality for simplified layout and lower component count; versus MX28LV640E-25P, it preserves 5 V system compatibility and lower standby current, making it optimal for cost-sensitive industrial upgrades.
Availability
AT28C64X-25PI is available at Aetrix Electronics and suitable for industrial PLC configuration storage, medical device calibration memory, and telecom line card boot firmware requiring stable component supply and long-term lifecycle support.
Supply support for AT28C64X-25PI 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, nonvolatile memory, and secure authentication ICs.
The AT28C64X series was designed as a drop-in parallel EEPROM replacement for legacy EPROM and SRAM sockets in industrial and telecom systems, emphasizing 5 V compatibility, JEDEC pinout adherence, and robust write-protection logic.
FAQ
What is the maximum read access time specified for AT28C64X-25PI?
The AT28C64X-25PI has a maximum read access time of 250 ns, measured from address valid to valid data on I/O0–I/O7. This value is guaranteed across the full industrial temperature range (–40°C to +85°C) and 5 V ±10% supply, enabling direct interface with 4 MHz microprocessors without wait-state insertion. The "25" in the part number explicitly denotes this 250 ns speed grade.
Does AT28C64X-25PI include a functional RDY/BUSY pin?
No, AT28C64X-25PI does not implement the RDY/BUSY function. Per the datasheet, pin 1 is designated NC (No Connect) for all AT28C64X variants, including AT28C64X-25PI. Write completion must be detected using DATA polling on I/O7 instead. This distinguishes it from the AT28C64B family, where pin 1 is an active open-drain RDY/BUSY output.
What write endurance rating applies to AT28C64X-25PI?
The AT28C64X-25PI is rated for 10,000 (10⁴) write/erase cycles, as confirmed in the "Features" section and ordering information table. This endurance level is validated under standard industrial operating conditions and is sufficient for firmware updates, configuration changes, and calibration storage in most embedded applications. Higher endurance (100,000 cycles) requires the "E" suffix variant (e.g., AT28C64E).
How is write protection implemented in AT28C64X-25PI?
AT28C64X-25PI implements three-tiered write protection: (1) VCC sense - writes disabled if supply drops below ~3.8 V; (2) power-on delay - automatic 5 ms lockout after VCC reaches threshold; and (3) signal-level inhibition - writes blocked unless CE and WE are low while OE is high. These mechanisms prevent accidental writes during power transitions or software glitches.
What package type and lead count does AT28C64X-25PI use?
AT28C64X-25PI uses a 28-lead Plastic Dual Inline Package (PDIP), 0.600" wide, per JEDEC standard MS-011 AB. The "PI" suffix in the part number explicitly denotes this PDIP industrial-temperature package. Pin spacing is 0.100", and the package is through-hole mountable with standard 0.025" diameter holes.
AT28C64X-25PI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 1ms
- Access Time:
- 250 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT28C64X-25PI FAQ
1.How can I place an order for AT28C64X-25PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-25PI 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 AT28C64X-25PI reliable?
The price and inventory of AT28C64X-25PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-25PI is usually 5 days.
3.What payment methods are accepted for AT28C64X-25PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-25PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-25PI?
AT28C64X-25PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-25PI 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 AT28C64X-25PI?
For technical support, including AT28C64X-25PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-25PI requirements.
6.How does Aetrix verify that AT28C64X-25PI is sourced from the original manufacturer or authorized distributors?
All AT28C64X-25PI 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 AT28C64X-25PI meets industry standards.
7.What is the process for return or replacement of AT28C64X-25PI?
All AT28C64X-25PI units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-25PI, 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 AT28C64X-25PI part is unused and in its original packaging.
Return procedure for AT28C64X-25PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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