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Microchip Technology AT28C64-25PC
- Part No.:
- AT28C64-25PC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28C64-25PC.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,891
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Product details
Overview
AT28C64-25PC from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 250 ns read access time, 1 ms or 200 µs byte write capability, and CMOS/TTL-compatible I/O - used for nonvolatile configuration storage in industrial microcontroller systems requiring field-updatable firmware parameters.
For engineers reviewing the AT28C64-25PC datasheet, AT28C64-25PC pinout, AT28C64-25PC application, or AT28C64-25PC equivalent, key selection considerations include its self-timed write cycle, READY/BUSY or DATA polling support, 5V ±10% supply operation, 10⁴/10⁵ endurance rating, and compatibility with legacy 8-bit bus architectures without external timing logic.
Technical Context
The AT28C64-25PC implements a parallel EEPROM architecture with internal address/data latching and an autonomous control timer that manages erase-before-write sequencing. It supports two write detection methods: open-drain RDY/BUSY signaling and DATA polling on I/O7, enabling flexible integration into microprocessor-based systems without dedicated wait-state generators.
Its dual-line chip enable (CE) and output enable (OE) control allows precise bus contention management during mixed read/write operations. The device operates across commercial (0°C to 70°C) and industrial (−40°C to +85°C) temperature ranges with 30 mA active current and 100 µA CMOS standby current, meeting legacy embedded system power budgets.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8), sufficient for boot code, calibration tables, or device configuration data in 8-bit systems. |
| Read Access Time | 250 ns max - compatible with 4 MHz Z80, 8051, and 68000-based systems without wait states. |
| Byte Write Time | 1 ms standard or 200 µs (E-version); enables full memory rewrite in ≤1.6 s for field firmware updates. |
| Endurance | 10⁴ cycles (standard) or 10⁵ cycles (AT28C64E variant); supports frequent parameter logging in data loggers. |
| Data Retention | 10 years at 85°C - ensures long-term reliability in unattended industrial controllers. |
| Supply Voltage | 5 V ±10%; eliminates need for precision voltage regulation in legacy 5V designs. |
| Interface | Parallel byte-wide JEDEC pinout; directly replaces SRAM or EPROM in existing PCB layouts. |
Pinout & Package
AT28C64-25PC is supplied in a 28-lead, 0.600" wide plastic DIP (PDIP) package per JEDEC MS-011 AB, with 0.3" row spacing and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus for 8K-word addressing; A0 = LSB, A12 = MSB. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; tristated when CE or OE high; supports DATA polling on I/O7. |
| CE | Chip Enable | Active-low chip select; must be low for read/write; enables write inhibit when high. |
| OE | Output Enable | Active-low output control; used with CE to prevent bus contention during reads. |
| WE | Write Enable | Active-low write strobe; latches address/data on falling/rising edges; initiates self-timed write. |
| RDY/BUSY | Open-Drain Status Output | Pulled low during write; released upon completion; supports wired-OR multi-device status lines. |
| VCC | Power Supply | +5 V ±10%; powers core logic and memory array; includes VCC sense for write protection. |
| GND | Ground Reference | Signal and power return; decoupling capacitor required near VCC pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed byte write cycle | Eliminates external timing circuitry; frees CPU bus after address/data latch for concurrent tasks. |
| READY/BUSY and DATA polling | Dual asynchronous write completion detection - supports both hardware interrupt and software polling designs. |
| Write protection mechanisms | VCC sense (<3.8 V inhibits write), 5 ms power-on delay, and CE/OE/WE logic-level inhibition prevent accidental writes. |
| JEDEC-standard pinout | Enables drop-in replacement of 2764 EPROM or 6264 SRAM in existing 28-pin sockets without layout changes. |
| Extended identification memory | 32 bytes at 1FE0H–1FFFH for unique device serialization or calibration data storage. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Memory |
|---|---|
|
Use Scenario: Storing sensor calibration coefficients and operational thresholds in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed via 8-bit parallel bus during system boot and runtime reconfiguration. Use Value: Enables field recalibration without firmware reflashing; retains settings across 10+ years and 10⁴ write cycles under industrial thermal cycling. |
Use Scenario: Holding patient-specific therapy parameters and device serial traceability data in portable infusion pumps and diagnostic monitors. IC Role / Device Role / Timing Role: Secure, low-power configuration memory interfaced to 8051 or ARM7-based controllers with strict data integrity requirements. Use Value: Guarantees 10-year data retention at 55°C ambient and supports audit-ready device identification via dedicated 32-byte ID space. |
| Legacy Test Equipment Firmware Patching | Avionics System Boot Parameter Storage |
|
Use Scenario: Field-updating instrument firmware patch tables and measurement algorithm coefficients in benchtop oscilloscopes and signal generators. IC Role / Device Role / Timing Role: Parallel-accessed patch memory mapped into CPU address space; updated via host PC over RS-232 or GPIB. Use Value: 200 µs fast write (E-version) reduces downtime during firmware updates; 250 ns read speed maintains real-time measurement throughput. |
Use Scenario: Storing flight-critical initialization vectors, sensor bias offsets, and mission-specific configuration flags in airborne navigation units. IC Role / Device Role / Timing Role: Radiation-tolerant (by design heritage), nonvolatile parameter store accessed during cold-start boot sequence. Use Value: Industrial-grade temperature range (−40°C to +85°C) and 10⁴-cycle endurance meet DO-160 environmental compliance for avionics subsystems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-25PC | Revised revision with improved data retention (10 years at 85°C vs. original 10 years at 25°C) and tighter tACC tolerance (250 ns guaranteed). | Preferred for new designs requiring extended high-temperature reliability; identical pinout and timing interface. | Select AT28C64B-25PC if long-term data integrity at elevated temperatures is critical; otherwise AT28C64-25PC remains valid for legacy-compliant builds. |
| MX28F640KC-25PC | Intel-compatible 64 Kbit parallel EEPROM with 250 ns access but no RDY/BUSY pin; uses only DATA polling for write detection. | Suitable where board space prohibits pull-up resistor for open-drain RDY/BUSY or where single-polling method suffices. | Choose MX28F640KC-25PC when RDY/BUSY hardware signaling is unnecessary and Intel footprint compatibility is prioritized. |
Compared with AT28C64-25PC, AT28C64B-25PC delivers enhanced high-temperature data retention without layout changes, while MX28F640KC-25PC trades RDY/BUSY support for Intel ecosystem alignment - making the original AT28C64-25PC optimal for cost-sensitive, legacy-maintained systems needing dual write-detection flexibility.
Availability
AT28C64-25PC is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, legacy test equipment, and avionics subsystems requiring stable component supply and long-lifecycle support.
Supply support for AT28C64-25PC 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 was a U.S.-based semiconductor manufacturer specializing in microcontrollers, nonvolatile memory, and secure authentication ICs before its acquisition by Microchip Technology in 2016.
The AT28C64 series was designed as a direct, pin-compatible EEPROM upgrade path for 2764 EPROMs and 6264 SRAMs in 8-bit embedded systems - emphasizing ease of migration, low power, and robust write protection.
FAQ
What is the maximum read access time specified for AT28C64-25PC?
The AT28C64-25PC has a maximum read access time (tACC) of 250 ns, as indicated by the "-25" suffix in its part number. This value is guaranteed across the full commercial temperature range (0°C to 70°C) and applies to all package variants including the PDIP (PC) version. The specification ensures compatibility with 4 MHz microprocessors without requiring wait-state insertion.
Does AT28C64-25PC support both READY/BUSY and DATA polling for write completion detection?
Yes, AT28C64-25PC supports both methods. Its RDY/BUSY pin (Pin 1) provides an open-drain active-low signal indicating write progress, while DATA polling uses I/O7 - which returns the complement of written data until completion, then asserts true data. Both mechanisms are fully functional in the PDIP package and require no external components.
What is the endurance rating of AT28C64-25PC, and how does it differ from the AT28C64E variant?
The standard AT28C64-25PC guarantees 10⁴ write/erase cycles. The "E" suffix variant (e.g., AT28C64E-25PC) offers extended endurance of 10⁵ cycles and faster 200 µs byte write time. The base AT28C64-25PC remains appropriate for infrequent configuration updates, whereas the E-version suits high-frequency logging or field-upgrade scenarios.
Can AT28C64-25PC be used as a direct replacement for 2764 EPROMs in existing designs?
Yes, AT28C64-25PC features JEDEC-approved byte-wide pinout and identical 28-pin PDIP footprint to the 2764 EPROM. It requires no external UV-erasure or programming hardware, operates from a single 5V supply, and supports the same address/data/control signals - enabling true socket-level replacement with only firmware-level changes to enable write operations.
What write protection mechanisms are implemented in AT28C64-25PC to prevent inadvertent writes?
AT28C64-25PC incorporates three independent write protection layers: (1) VCC sense circuitry that disables writing if supply drops below ~3.8 V; (2) a 5 ms internal power-on delay before write commands are accepted; and (3) logical inhibition - holding CE high, OE low, or WE high blocks all write cycles. These ensure robustness in noisy or unstable power environments.
AT28C64-25PC 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT28C64-25PC FAQ
1.How can I place an order for AT28C64-25PC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64-25PC 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 AT28C64-25PC reliable?
The price and inventory of AT28C64-25PC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64-25PC is usually 5 days.
3.What payment methods are accepted for AT28C64-25PC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64-25PC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64-25PC?
AT28C64-25PC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64-25PC 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 AT28C64-25PC?
For technical support, including AT28C64-25PC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64-25PC requirements.
6.How does Aetrix verify that AT28C64-25PC is sourced from the original manufacturer or authorized distributors?
All AT28C64-25PC 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 AT28C64-25PC meets industry standards.
7.What is the process for return or replacement of AT28C64-25PC?
All AT28C64-25PC units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64-25PC, 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 AT28C64-25PC part is unused and in its original packaging.
Return procedure for AT28C64-25PC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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