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Microchip Technology AT28C64X-20SI
- Part No.:
- AT28C64X-20SI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28C64X-20SI.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,096
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Product details
Overview
AT28C64X-20SI from Atmel is a 64K-bit (8K × 8) parallel EEPROM with 200 ns read access time, 1 ms byte write cycle, and JEDEC-standard 28-pin SOIC package for industrial temperature range (−40°C to +85°C). It operates at 5V ±10%, supports READY/BUSY polling and DATA polling, and delivers 30 mA active current with 100 µA CMOS standby current - used in firmware storage, configuration memory, and boot code retention in embedded controllers.
For engineers reviewing the AT28C64X-20SI datasheet, AT28C64X-20SI pinout, AT28C64X-20SI application, or AT28C64X-20SI equivalent, key selection criteria include verified 200 ns read timing, self-timed byte write with internal latching, RDY/BUSY signal behavior (NC on this variant), industrial-grade reliability (10⁴ write cycles, 10-year data retention), and compatibility with 5V microprocessor buses without external timing logic.
Technical Context
The AT28C64X-20SI implements a CMOS-based parallel EEPROM architecture with internal address/data latches and an autonomous control timer for self-timed byte writes. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance during mixed read/write operations.
Unlike flash memory, it supports true random-access byte-level writes without block erasure. The RDY/BUSY pin is not connected (NC) on the AT28C64X variant, requiring reliance on DATA polling via I/O7 for write completion detection - a design choice confirmed across all AT28C64X ordering codes including -20SI.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8 bits) - provides sufficient space for bootloader images or device configuration tables in resource-constrained systems. |
| Read Access Time | 200 ns max - ensures compatibility with 5 MHz microprocessor buses without wait-state insertion. |
| Byte Write Cycle | 1 ms typical - enables reliable field-updatable nonvolatile storage without external write timing circuitry. |
| Supply Voltage | 5 V ±10% - matches standard TTL/CMOS logic rails and eliminates need for dedicated voltage regulators. |
| Operating Temperature | −40°C to +85°C - qualified for industrial environments including motor drives, PLCs, and outdoor telemetry units. |
| Standby Current | 100 µA CMOS - reduces power budget in always-on embedded systems such as smart meters and sensor nodes. |
| Data Retention | 10 years - guarantees long-term integrity of calibration data or security keys without refresh cycles. |
| Endurance | 10,000 write/erase cycles - supports periodic firmware updates or logging in maintenance-critical equipment. |
Pinout & Package
AT28C64X-20SI uses a 28-lead, 0.300" wide plastic gull-wing small outline (SOIC) package per JEDEC MS-012AB, with pin 1 located at the top-left corner marked by a beveled edge or index notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; compatible with 8051, Z80, and 68K family address lines. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; supports true read/write without direction control pins - simplifies PCB routing. |
| CE | Chip Enable | Active-low global select; when high, places outputs in high-impedance state - essential for multi-device bus sharing. |
| OE | Output Enable | Active-low read gate; decouples memory output from bus independently of CE - prevents contention during partial decode. |
| WE | Write Enable | Active-low write strobe; initiates self-timed byte write on falling edge - no external write pulse generator required. |
| RDY/BUSY | Ready/Busy Output | No-connect (NC) on AT28C64X variants - write completion must be detected via DATA polling on I/O7. |
| VCC | Power Supply | +5 V supply input; internal VCC sense circuitry inhibits writes if voltage drops below 3.8 V - prevents corruption during brownout. |
| GND | Ground Reference | Signal and power ground common to all inputs/outputs - requires low-inductance connection to minimize noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed byte write | Internal control timer eliminates need for external write pulse generation or timing logic - reduces BOM count and layout complexity. |
| DATA polling support | I/O7 toggles complement-to-data during write; enables software-driven write completion detection without hardware interrupt lines. |
| JEDEC-standard pinout | Pin-compatible with industry-standard EPROMs and SRAMs - allows drop-in replacement in legacy designs using 28-pin DIP/SOIC footprints. |
| VCC write protection | Automatic inhibition below 3.8 V prevents inadvertent writes during power-up/down - critical for robust field operation. |
| Industrial temperature rating | Qualified from −40°C to +85°C - validated for use in automotive body control modules, industrial HMIs, and outdoor communications gear. |
Applications
| Firmware Storage | Configuration Memory |
|---|---|
|
Use Scenario: Storing boot loader and firmware images in microcontroller-based industrial controllers where power loss may occur during update. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed at system startup; provides deterministic 200 ns read latency for fast boot initialization. Use Value: Eliminates need for external programming hardware during field updates; 10,000-cycle endurance supports multiple firmware revisions over product lifetime. |
Use Scenario: Holding calibration coefficients, user preferences, and network settings in HVAC controllers and programmable logic relays. IC Role / Device Role / Timing Role: Byte-addressable configuration store updated infrequently but requiring guaranteed retention across 10+ years. Use Value: 100 µA standby current extends battery backup life; VCC-sense write protection prevents corruption during brownout events. |
| Boot Code Retention | Security Key Storage |
|
Use Scenario: Hosting secure boot code in medical diagnostic devices that require certified firmware integrity verification before execution. IC Role / Device Role / Timing Role: Read-only memory during normal operation; write-enabled only during authenticated firmware upgrade sequences. Use Value: Parallel interface enables direct CPU access without DMA or peripheral controller overhead - reducing boot time by >15% vs. serial EEPROM. |
Use Scenario: Storing cryptographic keys and device identity tokens in payment terminals and access control panels. IC Role / Device Role / Timing Role: Tamper-resistant nonvolatile storage with built-in write inhibit logic preventing unauthorized key overwrite. Use Value: Internal clear-before-write sequence ensures old keys are erased before new ones are committed - mitigating replay or rollback attacks. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-20SI | Same pinout and timing, but includes functional RDY/BUSY output (not NC); enhanced VCC sensing threshold stability. | Preferred where hardware-ready signaling is required instead of software polling - e.g., real-time OS contexts with strict interrupt latency budgets. | Select AT28C64B-20SI only if RDY/BUSY hardware handshake is needed; otherwise AT28C64X-20SI offers identical functionality at lower cost. |
| MX28LV640E-20SI | Same 64K×8 organization and SOIC-28 package, but uses 3.3 V core with 5 V tolerant I/O; 200 ns read, 5 ms write. | Suitable for mixed-voltage systems transitioning to lower-power logic; not directly interchangeable due to voltage domain mismatch and slower write speed. | Choose MX28LV640E-20SI only in new 3.3 V designs with margin for longer write latency; AT28C64X-20SI remains optimal for legacy 5 V systems. |
Compared with AT28C64B-20SI, AT28C64X-20SI saves board space by omitting RDY/BUSY pull-up and simplifies firmware by removing hardware interrupt dependency - while matching all timing, voltage, and endurance specs. Against MX28LV640E-20SI, AT28C64X-20SI avoids level-shifting complexity and delivers 5× faster write cycles in pure 5 V environments.
Availability
AT28C64X-20SI is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, and telecom infrastructure requiring stable component supply across extended product lifecycles.
Supply support for AT28C64X-20SI 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 wireless solutions before its acquisition by Microchip Technology in 2016.
The AT28C64X series was designed specifically for 5 V embedded systems needing byte-erasable, pin-compatible EEPROM replacements for UV-erasable EPROMs - emphasizing ease of integration, industrial reliability, and zero external timing components.
FAQ
What is the RDY/BUSY pin configuration on AT28C64X-20SI?
The RDY/BUSY pin (Pin 1) is designated as "No Connect" (NC) on all AT28C64X variants, including AT28C64X-20SI. This means the pin is internally unconnected and must remain floating or tied to ground per PCB layout best practices. Write completion must be monitored exclusively via DATA polling on I/O7, as confirmed in the AT28C64(X) datasheet revision 0001H.
Does AT28C64X-20SI support 3.3 V operation?
No, AT28C64X-20SI is strictly a 5 V ±10% device. Its DC characteristics - including VIH (2.0 V min), VIL (0.8 V max), and VCC operating range - are specified only for 4.5 V to 5.5 V. Attempting 3.3 V operation will result in undefined behavior, failed writes, or data corruption. For 3.3 V systems, consider Microchip's 25LC640 or similar SPI EEPROMs.
How many write cycles can AT28C64X-20SI endure?
AT28C64X-20SI is rated for 10,000 (10⁴) write/erase cycles per memory location, as stated in the "High Reliability" section of the datasheet. This endurance applies across the full industrial temperature range (−40°C to +85°C) and is validated under standard 5 V, 1 ms write conditions - sufficient for firmware updates or configuration changes occurring less than once per day over a 27-year operational lifespan.
Is AT28C64X-20SI pin-compatible with AT28C64-20SI?
Yes, AT28C64X-20SI is fully pin-compatible with AT28C64-20SI in the same SOIC-28 package. Both share identical pin functions, electrical characteristics, and timing parameters. The "X" suffix denotes the RDY/BUSY pin as NC, whereas the base AT28C64-20SI includes a functional RDY/BUSY output - but all other pins map identically and require no PCB changes for substitution.
What write protection mechanisms does AT28C64X-20SI implement?
AT28C64X-20SI implements three hardware-level write protections: (1) VCC sense - write inhibited if supply drops below ~3.8 V; (2) Power-on delay - automatic 5 ms lockout after VCC reaches threshold; and (3) Signal-level inhibit - write blocked unless CE and WE are low while OE is high. These features prevent accidental writes during power transitions or software glitches - a critical safeguard in AT28C64X-20SI deployments.
AT28C64X-20SI 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:
- 200 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28C64X-20SI FAQ
1.How can I place an order for AT28C64X-20SI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-20SI 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-20SI reliable?
The price and inventory of AT28C64X-20SI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-20SI is usually 5 days.
3.What payment methods are accepted for AT28C64X-20SI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-20SI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-20SI?
AT28C64X-20SI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-20SI 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-20SI?
For technical support, including AT28C64X-20SI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-20SI requirements.
6.How does Aetrix verify that AT28C64X-20SI is sourced from the original manufacturer or authorized distributors?
All AT28C64X-20SI 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-20SI meets industry standards.
7.What is the process for return or replacement of AT28C64X-20SI?
All AT28C64X-20SI units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-20SI, 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-20SI part is unused and in its original packaging.
Return procedure for AT28C64X-20SI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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