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Microchip Technology AT28C64X-20SC
- Part No.:
- AT28C64X-20SC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AT28C64X-20SC.pdf
- Description:
- IC EEPROM 64KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,431
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Product details
Overview
AT28C64X-20SC from Atmel is a 64 Kbit (8K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, 1 ms or 200 µs byte write capability, and CMOS/TTL-compatible I/O - used for nonvolatile configuration storage in industrial microcontroller systems requiring field-upgradable firmware parameters.
For engineers reviewing the AT28C64X-20SC datasheet, AT28C64X-20SC pinout, AT28C64X-20SC application, or AT28C64X-20SC equivalent, this page delivers verified timing specs, RDY/BUSY behavior clarification, DATA polling implementation details, endurance and retention data, and real-world substitution guidance for legacy embedded designs.
Technical Context
The AT28C64X-20SC operates as a drop-in parallel memory replacement for SRAM in read cycles and integrates self-timed byte write logic with internal address/data latching and automatic erase-before-write. Its READY/BUSY pin is unconnected (NC), requiring reliance on DATA polling via I/O7 for write completion detection.
It supports dual write initiation methods (WE- or CE-controlled), features VCC sense and power-on delay write protection, and includes 32 bytes of user-accessible identification EEPROM at addresses 1FE0H–1FFFH using A9 = 12 V. The device uses Atmel's nonvolatile floating-gate technology with built-in error correction for enhanced data retention.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 64 Kbit (8,192 × 8 bits) - provides sufficient space for boot code flags, calibration tables, or device configuration registers in resource-constrained MCU systems. |
| Read Access Time | 200 ns max - enables direct interface with 5 MHz bus systems without wait states, matching typical 8-bit microprocessor timing budgets. |
| Byte Write Time | 1 ms (standard) or 200 µs (E variant only) - determines minimum firmware update latency per parameter; AT28C64X-20SC uses standard 1 ms cycle. |
| Endurance | 10,000 write/erase cycles - supports infrequent field updates (e.g., once per device lifetime or per maintenance cycle) in industrial control applications. |
| Data Retention | 10 years at 85°C - ensures long-term validity of stored calibration or serial number data without refresh in sealed enclosures. |
| Supply Voltage | 5 V ±10% - compatible with legacy 5 V logic rails and eliminates need for dedicated voltage regulators in retrofitted designs. |
| Standby Current | 100 µA (CMOS mode) - reduces quiescent power in battery-backed or energy-sensitive monitoring nodes. |
Pinout & Package
AT28C64X-20SC is supplied in a 28-lead, 0.300" wide plastic SOIC (Small Outline Integrated Circuit) package per JEDEC MS-012 standard, with gull-wing leads and surface-mount compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A12 | Address Inputs | 13-bit address bus supporting full 8K-word addressing; A0 is LSB, A12 is MSB. |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel data path; I/O7 used for DATA polling during write cycles. |
| CE | Chip Enable | Active-low chip select; must be low for read/write access; high disables outputs and enters standby. |
| OE | Output Enable | Active-low output control; used with CE to gate data reads and prevent 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 variants - not bonded; write completion must be detected via DATA polling only. |
| VCC | Power Supply | +5 V supply input; internal VCC sense circuitry inhibits writes if voltage drops below ~3.8 V. |
| GND | Ground Reference | Signal and power ground return; decoupling capacitor required within 1 cm of VCC pin. |
Key Features
| Feature | Design Value |
|---|---|
| Self-timed byte write | Eliminates external timing circuitry - internal control timer handles erase-and-program sequence automatically after WE pulse. |
| DATA polling support | Enables software-driven write completion detection via I/O7 complement toggle, essential when RDY/BUSY is NC. |
| VCC sense & power-on delay | Prevents inadvertent writes during power ramp-up or brown-out by disabling WE until VCC ≥ 3.8 V and 5 ms timeout expires. |
| JEDEC byte-wide pinout | Ensures PCB layout compatibility with industry-standard EPROM/SRAM footprints, simplifying legacy board redesigns. |
| User identification EEPROM | 32-byte reserved area (1FE0H–1FFFH) accessible with A9 = 12 V - usable for MAC address storage, calibration checksums, or manufacturing traceability. |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Parameter Retention |
|---|---|
Use Scenario: Storing sensor offset values, alarm thresholds, and operational mode settings in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration register bank accessed during system boot and runtime parameter updates via microcontroller parallel bus. Use Value: Ensures settings survive power loss and enable deterministic startup; 10-year retention meets IEC 61508 SIL-2 requirements for safety-critical infrastructure. |
Use Scenario: Preserving calibrated gain/offset coefficients for analog front-end circuits in portable diagnostic equipment subject to periodic recalibration. IC Role / Device Role / Timing Role: Dedicated parameter EEPROM interfaced directly to ADC/DAC controller MCU, updated only during service mode. Use Value: Eliminates need for battery-backed RAM; 10,000-cycle endurance exceeds expected service life of 5–10 years with annual calibration. |
| Legacy Automotive ECU Bootloader Settings | Point-of-Sale Terminal Firmware Patch Storage |
Use Scenario: Holding bootloader jump vectors, security keys, and CAN node ID assignments in automotive engine control units where flash reprogramming is restricted. IC Role / Device Role / Timing Role: Secure configuration vault mapped into MCU memory space; write-protected via VCC sensing and OE/CE/WE logic. Use Value: Provides tamper-resistant, field-updatable settings without modifying main flash; 5 V operation matches legacy automotive MCU voltage domains. |
Use Scenario: Storing minor firmware patches or localization strings in retail payment terminals where full flash reflash requires certified tools and downtime. IC Role / Device Role / Timing Role: Hot-swappable patch memory accessed via parallel bus during terminal idle periods; updated via secure host command. Use Value: Enables rapid regionalization or compliance updates without hardware revision; JEDEC pinout allows reuse of existing PCB footprint. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28C64B-20SC | Revised die version with improved data retention (10 years at 85°C vs. original 10 years at 25°C); identical pinout, timing, and command set. | Preferred for new designs targeting extended temperature operation; same PCB and firmware compatibility. | Select AT28C64B-20SC for new production runs requiring guaranteed retention at industrial temperatures. |
| MX28LV640CT-20G | 3.3 V core with 5 V tolerant I/O; 200 ns access; 100K endurance; no RDY/BUSY pin; requires level-shifting for pure 5 V systems. | Suitable for mixed-voltage platforms; not drop-in for 5 V-only buses without interface adaptation. | Choose MX28LV640CT-20G only when migrating toward lower-power 3.3 V architectures and redesigning I/O buffering. |
Compared with AT28C64X-20SC, AT28C64B-20SC offers validated high-temperature retention without layout or firmware changes, while MX28LV640CT-20G introduces voltage domain complexity but doubles endurance - making the former ideal for drop-in reliability upgrades and the latter appropriate only for planned voltage architecture transitions.
Availability
AT28C64X-20SC is available at Aetrix Electronics and suitable for industrial control systems, medical instrumentation, legacy automotive ECUs, and point-of-sale terminals requiring stable component supply across extended product lifecycles.
Supply support for AT28C64X-20SC 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 fabless semiconductor company specializing in microcontrollers, nonvolatile memory, and secure authentication ICs for industrial, automotive, and consumer applications.
The AT28C64X series was designed as a pin-compatible, low-power upgrade path from UV-erasable EPROMs and early EEPROMs, targeting 5 V embedded systems needing reliable, field-programmable nonvolatile storage without external timing components.
FAQ
What is the RDY/BUSY pin behavior on AT28C64X-20SC?
The RDY/BUSY pin (Pin 1) is a no-connect (NC) on all AT28C64X variants, including AT28C64X-20SC. It is not bonded internally, so status signaling must rely exclusively on DATA polling via I/O7. This differs from the base AT28C64, which supports open-drain RDY/BUSY output. Designers must implement polling logic in firmware to detect write completion.
Does AT28C64X-20SC support fast 200 µs byte writes?
No, AT28C64X-20SC implements the standard 1 ms byte write cycle. The 200 µs write speed is exclusive to the "E" suffix variants (e.g., AT28C64XE-20SC), which use a different internal cell structure and higher endurance (100K cycles). The "X" in AT28C64X denotes the NC RDY/BUSY feature, not enhanced write speed.
How is write protection implemented on AT28C64X-20SC?
AT28C64X-20SC uses three-tiered write protection: (1) VCC sense - writes disabled if supply drops below ~3.8 V; (2) Power-on delay - 5 ms internal timer prevents writes until VCC stabilizes; (3) Logic-level inhibition - holding OE low, CE high, or WE high blocks all write operations. No external hardware lock is needed.
Can AT28C64X-20SC be used as a direct replacement for AT28C64-20SC?
Yes, AT28C64X-20SC is functionally and pinout-compatible with AT28C64-20SC except for RDY/BUSY functionality. Both share identical timing, voltage, endurance, and command sets. However, firmware relying on RDY/BUSY must be modified to use DATA polling instead - no PCB change is required, but software adaptation is necessary.
What is the purpose of the 32-byte identification area in AT28C64X-20SC?
The 32-byte identification area (addresses 1FE0H–1FFFH) in AT28C64X-20SC is user-programmable EEPROM space accessible only when A9 is raised to 12 V ±0.5 V. It is commonly used for storing unique device identifiers, calibration checksums, manufacturing lot codes, or MAC address fragments - separate from main memory and protected from accidental overwrite during normal operation.
AT28C64X-20SC 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:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT28C64X-20SC FAQ
1.How can I place an order for AT28C64X-20SC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C64X-20SC 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-20SC reliable?
The price and inventory of AT28C64X-20SC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C64X-20SC is usually 5 days.
3.What payment methods are accepted for AT28C64X-20SC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C64X-20SC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C64X-20SC?
AT28C64X-20SC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C64X-20SC 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-20SC?
For technical support, including AT28C64X-20SC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C64X-20SC requirements.
6.How does Aetrix verify that AT28C64X-20SC is sourced from the original manufacturer or authorized distributors?
All AT28C64X-20SC 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-20SC meets industry standards.
7.What is the process for return or replacement of AT28C64X-20SC?
All AT28C64X-20SC units undergo pre-shipment inspection (PSI). If there is an issue with AT28C64X-20SC, 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-20SC part is unused and in its original packaging.
Return procedure for AT28C64X-20SC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28C64X-20SC Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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AT24C02C-SSHM-T
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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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