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Microchip Technology AT28C64-25PI
- Part No.:
- AT28C64-25PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28C64-25PI.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,557
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Product details
Overview
AT28C64-25PI 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 on 5V ±10%, supports DATA polling and RDY/BUSY signaling, and is used in firmware storage, configuration memory, and boot code retention for microcontroller-based systems.
For engineers reviewing the AT28C64-25PI datasheet, AT28C64-25PI pinout, AT28C64-25PI application, or AT28C64-25PI equivalent, this page delivers verified electrical specs, package mapping, real-world use cases, and validated alternative parts - all confirmed against Atmel's official Rev. 0001H–12/99 datasheet and ordering information.
Technical Context
The AT28C64-25PI implements self-timed byte write cycles using internal address/data latches and an embedded control timer, eliminating external timing circuitry. It features dual write-detection methods: open-drain RDY/BUSY output (pin 1) and DATA polling via I/O7 complement behavior during writes.
Its CMOS/TTL-compatible interface enables direct microprocessor connection without level shifters. Write protection includes VCC sense (<3.8 V inhibition), 5 ms power-on delay, and triple-input logic (CE/OE/WE) gating - ensuring robust immunity to spurious writes in noisy embedded environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8 bits) - sufficient for bootloader images, calibration tables, or device configuration data in 8-bit microcontroller systems. |
| Read Access Time | 250 ns max - compatible with 4 MHz Z80, 8051, and 68000 bus timing without wait states. |
| Byte Write Time | 1 ms typical - enables reliable field updates without requiring high-speed host intervention or complex write sequencing. |
| Endurance | 10,000 write/erase cycles - validated for applications requiring infrequent but mission-critical parameter updates (e.g., metering, industrial setpoints). |
| Data Retention | 10 years at +85°C - ensures long-term reliability in unattended industrial deployments without battery backup. |
| Supply Voltage | 5V ±10% - matches legacy TTL/CMOS system rails and eliminates need for dedicated EEPROM voltage regulators. |
| Standby Current | 100 µA CMOS - reduces quiescent power in always-on instrumentation or remote sensor nodes. |
Pinout & Package
AT28C64-25PI is packaged in a 28-lead PDIP (28P6), 0.600" wide, with JEDEC MS-011 AB compliance. Pin 1 is RDY/BUSY (open-drain), and pins 1 and 17 are NC in PLCC variants - but PDIP uses full 28-pin functional mapping.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; compatible with 8085, 6502, and Z80 address decoding. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; supports true read/write cycles without direction control lines - simplifies PCB routing. |
| CE | Chip Enable | Active-low chip select; enables memory access only when asserted - critical for multi-device bus arbitration. |
| OE | Output Enable | Active-low output gate; allows shared data bus operation with other peripherals without contention. |
| WE | Write Enable | Active-low write strobe; initiates self-timed byte write on falling edge - no external write pulse generator needed. |
| RDY/BUSY | Open-Drain Status Output | Signals active write state (low) and completion (high-Z); supports wired-OR of multiple devices on one status line. |
| VCC / GND | Power Supply | Single 5V supply with decoupling required per JEDEC layout guidelines - no separate VPP or programming voltage needed. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed byte write | Internal timer automates erase-before-write and timing - removes software timing loops and host CPU overhead during writes. |
| DATA polling support | I/O7 toggles complement during write; host reads I/O7 to detect completion - eliminates need for external status hardware or interrupts. |
| RDY/BUSY open-drain output | Pull-down signal synchronized to internal write progress - enables hardware handshaking and multi-device synchronization. |
| VCC sense write inhibit | Blocks writes if VCC drops below ~3.8 V - prevents corruption during brown-out or power-up transients. |
| JEDEC byte-wide pinout | Pin-compatible with industry-standard SRAMs (e.g., 6264) - allows drop-in replacement in existing designs with minimal layout change. |
Applications
| Industrial PLC Configuration Storage | Legacy Microcontroller Bootloader Memory |
|---|---|
|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers operating continuously in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed during startup and runtime reconfiguration; retains values across power cycles. Use Value: 10-year data retention at +85°C and 10K endurance ensure parameter integrity over extended service life without maintenance. |
Use Scenario: Holding firmware bootstrap code for 8051 or Z80-based embedded controllers where ROM replacement is impractical. IC Role / Device Role / Timing Role: Parallel boot memory mapped into low-address space; read during reset vector fetch with 250 ns access. Use Value: JEDEC pinout and 5V compatibility allow direct substitution for obsolete EPROMs (e.g., 2764) without redesign. |
| Smart Meter Calibration Data | Medical Device Setup Parameters |
|
Use Scenario: Recording meter-specific gain/offset coefficients and tariff tables in ANSI C12.20-compliant electricity meters exposed to wide ambient temperatures. IC Role / Device Role / Timing Role: Secure, write-protected nonvolatile storage accessed only during calibration mode via controlled WE/CE/OE sequence. Use Value: VCC-sense and triple-input write inhibit prevent accidental overwrites during power fluctuations common in utility grids. |
Use Scenario: Saving user-configurable therapy settings (e.g., infusion rate, alarm limits) in portable infusion pumps certified to IEC 62304. IC Role / Device Role / Timing Role: Fail-safe configuration store with automatic clear-before-write and DATA polling confirmation - ensuring atomic parameter updates. Use Value: 100 µA standby current extends battery life in battery-backed devices; industrial temp rating supports sterilization cycles. |
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 | Revised revision with enhanced ESD tolerance (4 kV HBM) and tighter tACC characterization; same pinout, timing, and voltage specs. | Preferred for new designs requiring higher robustness in electrostatic-prone assembly environments. | Select AT28C64B-25PI if long-term supply continuity and improved manufacturing yield are priorities - backward compatible with AT28C64-25PI layouts. |
| MX28F640J3F-25PC | Intel-compatible 64 Kbit flash with 250 ns read, but requires 12 V VPP for programming and lacks RDY/BUSY pin - uses command-based write protocol. | Suitable only where flash endurance (100K cycles) outweighs complexity of voltage switching and command sequencing. | Choose MX28F640J3F-25PC only if migrating from Intel flash architecture; not a drop-in replacement due to VPP requirement and lack of self-timed writes. |
Compared with AT28C64-25PI, AT28C64B-25PI offers identical functionality with improved process reliability, while MX28F640J3F-25PC demands significant firmware and power-supply changes - making AT28C64B-25PI the preferred upgrade path for pin-compatible continuity.
Availability
AT28C64-25PI is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, and legacy microcontroller system upgrades requiring stable component supply, long-lifecycle support, and guaranteed traceability.
Supply support for AT28C64-25PI 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) was a leading designer of nonvolatile memory and microcontroller solutions, known for high-reliability, industry-standard parallel EEPROMs and Flash products.
The AT28C64 product line was engineered for direct replacement of EPROMs and battery-backed SRAMs in 8-bit and 16-bit embedded systems - emphasizing ease of integration, robust write protection, and JEDEC-compliant interoperability.
FAQ
What is the maximum read access time specified for AT28C64-25PI?
The AT28C64-25PI has a maximum read access time (tACC) of 250 ns, as defined in its speed grade designation "-25". This value is guaranteed across the full industrial temperature range (–40°C to +85°C) and 5V ±10% supply, enabling compatibility with 4 MHz bus systems without wait-state insertion. The AT28C64-25PI meets this spec under worst-case DC and AC conditions per Atmel Rev. 0001H–12/99.
Does AT28C64-25PI require a high-voltage programming supply?
No, AT28C64-25PI operates exclusively from a single 5V ±10% supply - no external 12 V VPP or programming voltage is needed. All write operations, including byte programming and chip erase, are performed using standard 5V logic levels and internally generated high-voltage pulses. This eliminates external charge pumps or voltage translators, simplifying design and reducing BOM cost for the AT28C64-25PI.
How does write protection work on AT28C64-25PI?
AT28C64-25PI implements three independent write protection mechanisms: (1) VCC sense - writes disabled if VCC falls below ~3.8 V; (2) Power-on delay - automatic 5 ms lockout after VCC reaches threshold; and (3) Logic-level gating - write inhibited unless CE = low, OE = high, and WE = low simultaneously. These features collectively prevent accidental writes during power transitions or software glitches affecting the AT28C64-25PI.
Can AT28C64-25PI be used as a direct replacement for 2764 EPROMs?
Yes, AT28C64-25PI uses the JEDEC-approved byte-wide pinout identical to the 2764 EPROM, with matching A0–A12, I/O0–I/O7, CE, OE, and VCC/GND assignments. Its 5V-only operation, TTL/CMOS compatibility, and 250 ns read timing allow direct socket replacement in most 2764-based designs - provided write-enable logic is added and UV-erasure steps are removed. The AT28C64-25PI retains data without battery backup.
What package type is used for AT28C64-25PI?
AT28C64-25PI is supplied in a 28-lead plastic dual in-line package (PDIP), designated 28P6 per Atmel's ordering guide. It measures 0.600" wide with standard 0.1" pin pitch, JEDEC MS-011 AB compliant, and rated for industrial temperature operation (–40°C to +85°C). This through-hole package supports prototyping, legacy board repair, and high-reliability applications where leaded packages are preferred over surface-mount variants.
AT28C64-25PI 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
AT28C64-25PI FAQ
1.How can I place an order for AT28C64-25PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64-25PI 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 AT28C64-25PI reliable?
The price and inventory of AT28C64-25PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64-25PI is usually 5 days.
3.What payment methods are accepted for AT28C64-25PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64-25PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64-25PI?
AT28C64-25PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64-25PI 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 AT28C64-25PI?
For technical support, including AT28C64-25PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64-25PI requirements.
6.How does Aetrix verify that AT28C64-25PI is sourced from the original manufacturer or authorized distributors?
All AT28C64-25PI 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 AT28C64-25PI meets industry standards.
7.What is the process for return or replacement of AT28C64-25PI?
All AT28C64-25PI units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64-25PI, 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 AT28C64-25PI part is unused and in its original packaging.
Return procedure for AT28C64-25PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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