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Microchip Technology AT28C64X-20PI
- Part No.:
- AT28C64X-20PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28C64X-20PI.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,299
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Product details
Overview
AT28C64X-20PI from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, 1 ms byte write cycle, and CMOS/TTL-compatible I/O for direct microprocessor interfacing in embedded control and firmware storage applications.
For engineers reviewing the AT28C64X-20PI datasheet, AT28C64X-20PI pinout, AT28C64X-20PI application, or AT28C64X-20PI equivalent, this device supports READY/BUSY polling and DATA polling for write completion detection, operates at 5V ±10%, and delivers 100 µA standby current - critical for low-power industrial firmware retention and configuration memory.
Technical Context
The AT28C64X-20PI implements self-timed byte write cycles with internal address/data latching and automatic clear-before-write logic, eliminating external timing circuitry. Its RDY/BUSY output is unconnected (NC), requiring reliance on DATA polling via I/O7 to detect write completion.
It uses standard parallel memory interface signaling: CE and OE jointly enable read access; WE initiates byte writes with edge-triggered latching. The device includes VCC sense (3.8 V threshold), power-on delay (~5 ms), and three-level write inhibit (OE high, CE high, or WE high) for robust inadvertent-write protection.
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 data in 8-bit microcontroller systems. |
| Read Access Time | 200 ns - enables direct replacement of SRAM in legacy 8051/68K-based systems without wait-state insertion. |
| Byte Write Time | 1 ms - fixed duration for standard write mode; no external timing components required due to internal control timer. |
| Supply Voltage | 5 V ±10% - compatible with legacy TTL/CMOS logic rails and eliminates need for dedicated EEPROM voltage regulators. |
| Standby Current | 100 µA - ensures minimal power draw during system sleep modes in battery-backed industrial controllers. |
| Endurance | 10⁴ write/erase cycles - validated for infrequent field updates such as parameter tuning or firmware patching. |
| Data Retention | 10 years at 85°C - guarantees long-term integrity of stored calibration or serial ID data in industrial environments. |
Pinout & Package
AT28C64X-20PI is packaged in a 28-lead PDIP (28P6), 0.600" wide, with JEDEC MS-011 AB compliance and industrial temperature range (-40°C to +85°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; A12 is MSB for 64 Kbit capacity. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling during write cycles to signal completion. |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access. |
| OE | Output Enable | Active-low output control; disables outputs (high-Z) when high, preventing bus contention. |
| WE | Write Enable | Active-low write strobe; falling edge latches address, rising edge latches data for byte programming. |
| RDY/BUSY | Status Output | No-connect (NC) on AT28C64X variant - write status must be monitored via I/O7 DATA polling only. |
| VCC | Power Supply | +5 V ±10% supply input; internal VCC sense prevents writes below ~3.8 V. |
| GND | Ground Reference | Signal and power return; decoupling capacitor placement near pin critical for noise immunity during write cycles. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed byte write | Eliminates external timing circuitry; internal control timer manages erase-and-program sequence automatically. |
| DATA Polling (I/O7) | Enables software-driven write completion detection without hardware interrupt lines or additional pins. |
| JEDEC byte-wide pinout | Ensures drop-in compatibility with existing SRAM-based PCB layouts and memory controllers. |
| VCC sense & power-on delay | Prevents partial writes during power ramp-up or brownout conditions, improving data reliability. |
| 32-byte identification area | Provides user-accessible space at addresses 1FE0H–1FFFH for serialization, revision tracking, or calibration offsets. |
Applications
| Industrial PLC Configuration Storage | Embedded System Bootloader Parameters |
|---|---|
Use Scenario: Storing I/O mapping, PID tuning constants, and alarm thresholds in programmable logic controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during startup and runtime via 8-bit parallel bus; retains values across power cycles. Use Value: 10-year data retention at 85°C ensures consistent operation without recalibration; 10⁴ endurance supports quarterly firmware updates. |
Use Scenario: Holding bootloader version, secure boot keys, and hardware-specific initialization flags in medical or test equipment with strict revision control. IC Role / Device Role / Timing Role: Firmware parameter store interfaced directly to 8051 or Z80 derivatives; accessed during cold boot before RAM initialization. Use Value: 200 ns read access avoids wait states; 5 V ±10% tolerance matches legacy board power rails without level-shifting. |
| Point-of-Sale Terminal Serial ID | Automotive ECU Calibration Tables |
Use Scenario: Storing unique unit identifiers, MAC addresses, and regulatory certification codes in retail terminals deployed globally. IC Role / Device Role / Timing Role: Read-only serial ID memory written once at manufacturing; accessed via parallel bus during system enumeration. Use Value: 32-byte dedicated ID area (1FE0H–1FFFH) simplifies traceability; 100 µA standby current extends battery backup life. |
Use Scenario: Retaining engine calibration maps, sensor offset corrections, and emission control parameters in automotive body control modules. IC Role / Device Role / Timing Role: Field-updatable nonvolatile memory accessed by 16-bit MCU during key-on diagnostics and runtime adjustments. Use Value: Industrial temperature rating (-40°C to +85°C) meets AEC-Q100 ambient requirements; write inhibit logic prevents corruption during ignition transients. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-20PI | Same 200 ns access, but includes functional RDY/BUSY pin (not NC); higher endurance (10⁵ cycles) and faster write (200 µs) in E variant. | Supports hardware-ready signaling; suitable where RDY/BUSY line sharing across multiple devices is required. | Select AT28C64B-20PI if hardware status signaling is needed; AT28C64X-20PI is preferred when board layout rework must be avoided and DATA polling suffices. |
| MX28LV640BTC-20G | 64 Kbit parallel EEPROM with 200 ns access, but requires 3.3 V supply and has different pinout (no A12, uses A11 as MSB); no built-in VCC sense. | Designed for 3.3 V systems; incompatible with 5 V logic without level translation; lacks integrated write protection features. | Choose MX28LV640BTC-20G only for new 3.3 V designs; AT28C64X-20PI remains optimal for 5 V legacy upgrades and robustness-critical applications. |
Compared with AT28C64B-20PI, AT28C64X-20PI trades RDY/BUSY functionality for guaranteed pinout compatibility with older AT28C64 layouts; versus MX28LV640BTC-20G, it preserves 5 V operation and integrated write safeguards - making it the most reliable choice for industrial retrofit and firmware retention where voltage and timing constraints are fixed.
Availability
AT28C64X-20PI is available at Aetrix Electronics and suitable for industrial PLC configuration storage, embedded system bootloader parameters, and point-of-sale terminal serial ID applications requiring stable component supply and long-lifecycle support.
Supply support for AT28C64X-20PI 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 for industrial, automotive, and consumer applications.
The AT28C64X series belongs to Atmel's parallel EEPROM product line, designed specifically for 5 V systems requiring pin-compatible, low-power, and high-reliability firmware and configuration storage without external timing components.
FAQ
What is the RDY/BUSY pin configuration on AT28C64X-20PI?
The RDY/BUSY pin (Pin 1) on AT28C64X-20PI is designated as No Connect (NC) per the datasheet. Unlike the AT28C64B variant, this version does not implement the open-drain RDY/BUSY output. Engineers must use DATA polling on I/O7 to detect write completion, which is fully supported and functionally equivalent for most microprocessor-controlled implementations.
Does AT28C64X-20PI support 3.3 V operation?
No, AT28C64X-20PI is specified exclusively for 5 V ±10% operation (4.5 V to 5.5 V). It is not rated for 3.3 V supply and lacks 3.3 V logic-level compatibility. Attempting to operate AT28C64X-20PI at 3.3 V will result in unreliable reads, failed writes, and potential data corruption due to insufficient VCC for internal charge pumps and sensing circuits.
How is write protection implemented in AT28C64X-20PI?
AT28C64X-20PI implements three-tiered write protection: (1) VCC sense inhibits writes below ~3.8 V; (2) a ~5 ms internal power-on delay prevents writes during supply ramp-up; and (3) holding OE high, CE high, or WE high blocks all byte write cycles. These features ensure robust immunity to noise-induced or brownout-triggered unintended programming.
Can AT28C64X-20PI be used as a direct replacement for standard SRAM in existing designs?
Yes - AT28C64X-20PI uses a JEDEC-approved byte-wide pinout identical to common 8K × 8 SRAMs (e.g., 6264), enabling drop-in replacement in many cases. However, write cycles require software coordination (via DATA polling), and the device draws active current only during reads/writes - unlike SRAM, which consumes power continuously while enabled.
What is the purpose of the 32-byte identification area in AT28C64X-20PI?
The 32-byte identification area (addresses 1FE0H–1FFFH) in AT28C64X-20PI is user-programmable EEPROM space intended for device serialization, manufacturing date codes, calibration coefficients, or firmware version stamps. It is accessed using the same parallel interface and timing as main memory, with A9 raised to 12 V ±0.5 V to enable programming mode.
AT28C64X-20PI 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:
- 200 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-20PI FAQ
1.How can I place an order for AT28C64X-20PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-20PI 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-20PI reliable?
The price and inventory of AT28C64X-20PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-20PI is usually 5 days.
3.What payment methods are accepted for AT28C64X-20PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-20PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-20PI?
AT28C64X-20PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-20PI 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-20PI?
For technical support, including AT28C64X-20PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-20PI requirements.
6.How does Aetrix verify that AT28C64X-20PI is sourced from the original manufacturer or authorized distributors?
All AT28C64X-20PI 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-20PI meets industry standards.
7.What is the process for return or replacement of AT28C64X-20PI?
All AT28C64X-20PI units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-20PI, 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-20PI part is unused and in its original packaging.
Return procedure for AT28C64X-20PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28C64X-20PI Tags
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