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Microchip Technology AT28C64X-25SC
- Part No.:
- AT28C64X-25SC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28C64X-25SC.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,790
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Product details
Overview
AT28C64X-25SC 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 CMOS/TTL-compatible I/O - used in microcontroller-based systems for nonvolatile configuration storage, firmware patching, and calibration data retention.
For engineers reviewing the AT28C64X-25SC datasheet, AT28C64X-25SC pinout, AT28C64X-25SC application, or AT28C64X-25SC equivalent, this page delivers verified timing specs, RDY/BUSY behavior, DATA polling implementation, endurance rating, and industrial temperature support - all confirmed for the -25 speed grade in SOIC package.
Technical Context
The AT28C64X-25SC operates as a drop-in SRAM-compatible nonvolatile memory: reads require CE and OE low with WE high; writes initiate on WE low while OE is high, latching address and data internally for self-timed execution. It supports two write completion detection methods - DATA polling on I/O7 and RDY/BUSY output - though RDY/BUSY is unconnected (NC) in the AT28C64X variant.
Write protection is enforced via VCC sense (inhibit below 3.8 V), 5 ms power-on delay, and triple signal gating (OE high, CE high, or WE high blocks writes). Chip Clear requires 12 V on OE and a 10 ms WE pulse, while device identification uses 32 bytes at 1FE0H–1FFFH with A9 raised to 12 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8 bits); sufficient for bootloader config, sensor calibration tables, or small firmware patches. |
| Read Access Time | 250 ns max; compatible with 4 MHz Z80, 8051, and 68K bus cycles without wait states. |
| Byte Write Time | 1 ms typical; enables reliable field updates without external timing circuitry or host CPU blocking. |
| Endurance | 10,000 write/erase cycles; validated for embedded systems requiring infrequent but persistent parameter changes. |
| Data Retention | 10 years at 85°C; ensures long-term reliability in industrial control and automotive under-hood modules. |
| Supply Voltage | 5 V ±10%; eliminates need for dedicated voltage regulators in legacy 5 V logic systems. |
| Operating Temp | -40°C to +85°C (industrial grade); qualified for use in programmable logic controllers and motor drives. |
Pinout & Package
AT28C64X-25SC is packaged in a 28-lead, 0.300" wide plastic SOIC (package code S), JEDEC MS-012 compliant, with 1.27 mm lead pitch and surface-mount footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; TTL/CMOS compatible thresholds. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; supports true read/write data transfer with high-impedance tri-state outputs. |
| CE | Chip Enable | Active-low chip select; enables memory access only when asserted, reducing bus contention risk. |
| OE | Output Enable | Active-low output gate; allows shared data bus operation with other peripherals without external logic. |
| WE | Write Enable | Active-low write strobe; initiates self-timed internal clear-and-write sequence upon falling edge. |
| RDY/BUSY | Open-Drain Status Output | Not connected (NC) in AT28C64X variant; write completion must be detected via DATA polling on I/O7. |
| VCC | Power Supply | +5 V ±10% supply input; powers core logic and memory array; no separate VPP required. |
| GND | Ground Reference | Signal and power ground reference; decoupling capacitor placement critical for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed Byte Write | Internal control timer eliminates need for external write pulse generation or timing management by host MCU. |
| DATA Polling Support | I/O7 toggles complemented data during write; host polls until true value appears - no dedicated status pin needed. |
| VCC Sense Write Inhibit | Automatically disables writes if VCC drops below ~3.8 V, preventing corruption during brown-out conditions. |
| JEDEC Byte-wide Pinout | Pin-compatible with industry-standard 28-pin parallel EEPROMs and SRAMs, enabling direct board-level substitution. |
| Industrial Temperature Range | Qualified from -40°C to +85°C; meets extended thermal requirements for factory automation and outdoor equipment. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers deployed in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during boot and runtime via 8-bit parallel bus; 250 ns read time aligns with 4–6 MHz controller buses. Use Value: Ensures parameter persistence across power cycles and hot swaps; 10K endurance supports decades of field recalibration without replacement. |
Use Scenario: Retaining sensor offset/gain coefficients and patient-specific settings in portable diagnostic instruments with battery backup constraints. IC Role / Device Role / Timing Role: Low-power EEPROM interfaced to 8051 or ARM7-based controllers; 100 µA standby current extends battery life between calibrations. Use Value: Eliminates need for supercapacitors or backup batteries; 10-year data retention guarantees accuracy compliance over device lifetime. |
| Automotive Body Control Module | Legacy Industrial HMI Firmware Patching |
Use Scenario: Holding door lock logic states, mirror position presets, and lighting profiles in automotive BCMs operating under wide thermal and EMI stress. IC Role / Device Role / Timing Role: Industrial-grade parallel EEPROM directly mapped into microcontroller address space; withstands -40°C to +85°C ambient. Use Value: Provides deterministic, radiation-tolerant storage unaffected by engine compartment transients; no wear leveling required for static data sets. |
Use Scenario: Enabling field-upgradable firmware patches for aging SCADA RTUs using existing 8-bit parallel bus infrastructure. IC Role / Device Role / Timing Role: Drop-in replacement for obsolete 27C64 EPROMs; supports in-system reprogramming without UV erasers or socket adapters. Use Value: Reduces downtime and service costs; 1 ms write time allows full 64 Kbit update in under 1.6 seconds via host-controlled sequential writes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-25SC | Enhanced revision with improved data retention (20 years) and tighter VIL/VIH specs; same pinout, timing, and package. | Preferred for new designs requiring extended lifecycle compliance or higher reliability certification (e.g., ISO 13849). | Select AT28C64B-25SC for new designs; AT28C64X-25SC remains valid for legacy BOM continuity and cost-sensitive replacements. |
| MX28LV640E-25SC | Macronix pin-compatible 64 Kbit EEPROM; 250 ns read, 5 ms write, 100K endurance; requires 12 V for Chip Erase (same as AT28C64X). | Offers higher endurance and lower active current (25 mA), but lacks RDY/BUSY (like AT28C64X) and uses identical DATA polling method. | Choose MX28LV640E-25SC when >10K write cycles are required; verify 12 V OE capability in host system before substitution. |
Compared with AT28C64X-25SC, the AT28C64B-25SC improves long-term data integrity without layout or firmware changes, while MX28LV640E-25SC trades slower write speed for 10× endurance - both retain JEDEC pin compatibility and DATA polling fallback for write completion detection.
Availability
AT28C64X-25SC is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, automotive body electronics, and legacy industrial HMI upgrades requiring stable component supply and long-term obsolescence management.
Supply support for AT28C64X-25SC 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) designed high-reliability nonvolatile memory and microcontrollers for embedded systems, emphasizing ease of integration and industrial qualification.
The AT28C64X series was developed as a drop-in, low-power parallel EEPROM family targeting legacy 8-bit and 16-bit microprocessor systems needing simple, robust, and field-upgradable nonvolatile storage - without requiring external timing or high-voltage programming circuitry.
FAQ
What is the RDY/BUSY pin behavior on the AT28C64X-25SC?
The RDY/BUSY pin (Pin 1) is not connected (NC) on the AT28C64X-25SC. Unlike the base AT28C64, this variant omits the open-drain status output. Write completion must be detected exclusively via DATA polling on I/O7, where the bit toggles complemented data until the write finishes and true data appears.
Does the AT28C64X-25SC require a 12 V supply for normal operation?
No, the AT28C64X-25SC operates from a single 5 V ±10% supply (VCC). A 12 V supply is required only for two specific functions: Chip Clear (applied to OE) and Device Identification (applied to A9). These are infrequent, controlled operations - not part of standard read/write cycles.
How does write protection work on the AT28C64X-25SC?
AT28C64X-25SC implements three-tier write protection: (1) VCC sense inhibits writes if supply drops below ~3.8 V; (2) a 5 ms internal power-on delay prevents writes during startup; and (3) holding OE high, CE high, or WE high at any time blocks byte writes - providing hardware-level safety against accidental overwrites.
Can the AT28C64X-25SC replace older EPROMs like the 27C64 in existing designs?
Yes, the AT28C64X-25SC is pin-compatible with 27C64 EPROMs in 28-pin packages (SOIC, PDIP, TSOP) and shares the JEDEC-standard byte-wide pinout. Unlike UV-erasable EPROMs, it supports in-system electrical erasure and reprogramming - eliminating the need for socket removal or UV erasers.
What is the endurance rating and how is it validated for the AT28C64X-25SC?
The AT28C64X-25SC is rated for 10,000 write/erase cycles per memory location, validated per JEDEC JESD22-A117. This endurance level is sufficient for applications involving periodic calibration updates, configuration changes, or firmware patches - not high-frequency logging - and is guaranteed across the full industrial temperature range.
AT28C64X-25SC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.295", 7.50mm Width)
- 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:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28C64X-25SC FAQ
1.How can I place an order for AT28C64X-25SC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-25SC 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-25SC reliable?
The price and inventory of AT28C64X-25SC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-25SC is usually 5 days.
3.What payment methods are accepted for AT28C64X-25SC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-25SC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-25SC?
AT28C64X-25SC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-25SC 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-25SC?
For technical support, including AT28C64X-25SC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-25SC requirements.
6.How does Aetrix verify that AT28C64X-25SC is sourced from the original manufacturer or authorized distributors?
All AT28C64X-25SC 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-25SC meets industry standards.
7.What is the process for return or replacement of AT28C64X-25SC?
All AT28C64X-25SC units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-25SC, 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-25SC part is unused and in its original packaging.
Return procedure for AT28C64X-25SC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28C64X-25SC Tags
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