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Microchip Technology AT28C64X-20JI
- Part No.:
- AT28C64X-20JI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT28C64X-20JI.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,339
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Product details
Overview
AT28C64X-20JI from Microchip Technology (formerly Atmel) is a 64K-bit (8K × 8) parallel EEPROM designed for nonvolatile byte-level write and read operations in embedded microcontroller systems. It features 200 ns read access time, 1 ms standard byte write cycle, 5V ±10% supply, JEDEC-standard 28-pin SOIC package, and industrial temperature range (–40°C to +85°C).
For engineers reviewing the AT28C64X-20JI datasheet, AT28C64X-20JI pinout, AT28C64X-20JI application, or AT28C64X-20JI equivalent, key selection criteria include self-timed write with RDY/BUSY or DATA polling support, CMOS/TTL compatibility, 10⁴ endurance cycles, 10-year data retention, and direct microprocessor interface without external timing logic.
Technical Context
The AT28C64X-20JI operates as a drop-in SRAM-compatible nonvolatile memory: CE/OE/WE control enables seamless integration into 8-bit bus architectures. Its internal address/data latches and self-timed write controller eliminate external wait-state generation.
Unlike flash devices, it supports true random-byte writes without block erase overhead. The RDY/BUSY pin is unconnected (NC) per AT28C64X specification, making DATA polling on I/O7 the sole hardware-based write completion detection method for this variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8), directly addressable via A0–A12 |
| Read Access Time | 200 ns - meets timing budgets for 5 MHz Z80, 8051, and 68K-based systems |
| Byte Write Time | 1 ms (standard mode) - no external timing circuitry required |
| VCC Supply | 5 V ±10% - compatible with legacy TTL/CMOS logic rails |
| Endurance | 10,000 write/erase cycles - sufficient for configuration storage and field calibration logs |
| Data Retention | 10 years at +85°C - validated for industrial deployment without refresh |
| Operating Temp | –40°C to +85°C - qualified for industrial control, instrumentation, and telecom edge nodes |
| Standby Current | 100 µA - enables low-power sleep modes in battery-backed systems |
Pinout & Package
AT28C64X-20JI is supplied in a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package (package code "SI" per ordering table), compliant with JEDEC MS-012AB. Pin 1 is index-marked; pins are numbered counter-clockwise from index corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus for full 8K-word decoding; no external address demultiplexing needed |
| I/O0–I/O7 | Bidirectional Data Bus | True 8-bit parallel interface; supports both read output and write input without direction control |
| CE | Chip Enable | Active-low chip select; enables device when low and disables outputs to high-Z when high |
| OE | Output Enable | Active-low read gate; allows output tri-state control independent of CE for bus sharing |
| WE | Write Enable | Active-low write strobe; initiates self-timed byte write on falling edge |
| RDY/BUSY | Status Output | No-connect (NC) for AT28C64X variant - write completion must be detected via DATA polling on I/O7 |
| VCC, GND | Power Rails | Single 5V supply; decoupling capacitor placement near pins critical for noise immunity during write |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed Byte Write | Internal control timer clears and programs each byte autonomously - eliminates need for external write pulse generators or timing firmware delays |
| DATA Polling Support | I/O7 toggles complemented data during write; stable true data indicates completion - enables efficient polling without dedicated status lines |
| Write Protection Logic | VCC sense (inhibits below 3.8 V), power-on delay (5 ms), and triple-gate inhibit (CE high / OE low / WE high) prevent accidental writes during power transitions |
| JEDEC-Compatible Pinout | Matches industry-standard 28-pin parallel EEPROM footprint - allows drop-in replacement of similar-density parts without PCB redesign |
| Device Identification Area | 32 bytes at 1FE0H–1FFFH accessible via A9 = 12 V - enables unique serialization, calibration data storage, or firmware version tagging |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Memory |
|---|---|
Use Scenario: Storing user-configurable I/O mapping, scaling factors, and alarm thresholds in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed during boot and runtime via 8-bit parallel bus. Use Value: Enables field-updatable settings without battery backup; 10⁴ endurance supports >10 years of daily reconfiguration. | Use Scenario: Retaining sensor calibration coefficients and patient-specific therapy parameters in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure, long-term parameter store interfaced to microcontroller's data bus during initialization and service mode. Use Value: 10-year data retention at +85°C ensures accuracy across device lifetime without recalibration; 5V compatibility simplifies power domain design. |
| Telecom Line Card Bootloader Storage | Automotive ECU Parameter Tables |
Use Scenario: Holding bootloader firmware images and hardware revision identifiers on carrier-grade line cards subject to frequent field updates. IC Role / Device Role / Timing Role: Parallel-programmable boot ROM mapped into microprocessor address space for cold-start execution. Use Value: 200 ns read access supports deterministic boot timing; industrial temp rating ensures reliability in enclosed chassis environments. | Use Scenario: Storing adaptive fuel trim tables and emission control constants in engine control units operating under under-hood thermal stress. IC Role / Device Role / Timing Role: Field-writable parameter memory accessed by MCU during closed-loop control loops. Use Value: –40°C to +85°C operation matches automotive under-hood requirements; byte-write capability enables real-time table updates without full-flash erase latency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-20JI | Same pinout, same speed grade, but includes functional RDY/BUSY output (pin 1 connected) | Enables hardware wait-state signaling; eliminates need for DATA polling software overhead | Select if system design requires active BUSY signaling and board layout accommodates pull-up on pin 1 |
| ST M28W640ECB90N1 | 64K×8 parallel EEPROM, 90 ns access, 3.3 V/5 V dual supply, different pinout (no RDY/BUSY, uses STATUS flag) | Requires voltage translation for pure 5 V systems; lacks JEDEC-compatibility for direct replacement | Select only for new designs targeting lower power or mixed-voltage environments; not a drop-in substitute |
Compared with AT28C64B-20JI, the AT28C64X-20JI trades hardware BUSY signaling for simplified board routing (NC pin 1), while ST M28W640ECB90N1 offers faster access and dual-supply flexibility at the cost of layout redesign and firmware adaptation.
Availability
AT28C64X-20JI is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, and telecom infrastructure requiring stable component supply, long-lifecycle assurance, and guaranteed traceability.
Supply support for AT28C64X-20JI 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 acquired Atmel in 2016 and maintains full product support, documentation, and manufacturing continuity for the AT28C64X family.
The AT28C64X series was designed specifically for legacy 8-bit microprocessor systems needing reliable, pin-compatible EEPROM with SRAM-like interface simplicity and industrial-grade environmental tolerance.
FAQ
What is the function of pin 1 (RDY/BUSY) on the AT28C64X-20JI?
Pin 1 on the AT28C64X-20JI is a no-connect (NC) terminal per the AT28C64X datasheet revision. Unlike the AT28C64B variant, the AT28C64X does not implement the RDY/BUSY open-drain output. Therefore, write completion for AT28C64X-20JI must be detected exclusively via DATA polling on I/O7, where the bit toggles until the write cycle finishes. This NC configuration simplifies board routing but requires firmware polling logic.
Does the AT28C64X-20JI support fast 200 µs byte writes?
No, the AT28C64X-20JI does not support the 200 µs fast write mode. That feature is exclusive to the AT28C64E variant (e.g., AT28C64E-20JI). The AT28C64X-20JI uses the standard 1 ms byte write cycle, as confirmed in the AC Write Characteristics table and Ordering Information section. Attempting to force shorter write pulses will result in incomplete programming or data corruption.
Can the AT28C64X-20JI be used in a 3.3 V system?
No, the AT28C64X-20JI is specified only for 5 V ±10% operation (4.5 V to 5.5 V). Its DC characteristics-including VIH, VIL, VOL, VOH, and internal charge pump-depend on nominal 5 V supply. Using it at 3.3 V violates absolute maximum ratings and will cause read failures, write inhibition, or premature wear. For 3.3 V systems, consider Microchip's 25LCxxx SPI EEPROMs or compatible parallel alternatives rated for 3.3 V.
How is write protection implemented on the AT28C64X-20JI?
The AT28C64X-20JI implements three-tiered hardware write protection: (1) VCC sense circuitry inhibits writes if supply drops below ~3.8 V; (2) a 5 ms internal power-on delay prevents writes during power ramp-up; and (3) any one of CE high, OE low, or WE high blocks write initiation. These mechanisms operate independently and require no software intervention, ensuring robust immunity to noise-induced or brownout-triggered writes.
What is the purpose of the 32-byte device identification area in the AT28C64X-20JI?
The AT28C64X-20JI includes 32 bytes of additional EEPROM space at addresses 1FE0H–1FFFH, accessible only when A9 is raised to 12 V ±0.5 V. This area is intended for permanent device-level data such as serial numbers, calibration constants, manufacturing date codes, or firmware version stamps. It operates independently of main array writes and retains data for the full 10-year specification period, enabling traceability and field-service diagnostics.
AT28C64X-20JI 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:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 64Kbit
- Memory Organization:
- 8K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 1ms
- Access Time:
- 200 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT28C64X-20JI FAQ
1.How can I place an order for AT28C64X-20JI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-20JI 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-20JI reliable?
The price and inventory of AT28C64X-20JI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-20JI is usually 5 days.
3.What payment methods are accepted for AT28C64X-20JI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-20JI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-20JI?
AT28C64X-20JI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-20JI 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-20JI?
For technical support, including AT28C64X-20JI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-20JI requirements.
6.How does Aetrix verify that AT28C64X-20JI is sourced from the original manufacturer or authorized distributors?
All AT28C64X-20JI 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-20JI meets industry standards.
7.What is the process for return or replacement of AT28C64X-20JI?
All AT28C64X-20JI units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-20JI, 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-20JI part is unused and in its original packaging.
Return procedure for AT28C64X-20JI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28C64X-20JI Tags
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M24C02-WMN6TP
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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24LC01BT-I/SN
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