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Microchip Technology AT28C040-20BC
- Part No.:
- AT28C040-20BC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-CDIP (0.600", 15.24mm)
- Datasheet:
-
AT28C040-20BC.pdf
- Description:
- IC EEPROM 4MBIT PARALLEL 32CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,046
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Product details
Overview
AT28C040-20BC from Atmel is a 4-Mbit (512K × 8) paged parallel EEPROM with 200 ns read access time, single 5V ±10% supply, and hardware/software data protection. It operates in commercial temperature range (0°C to 70°C), supports automatic 256-byte page writes, and is used for nonvolatile firmware storage in embedded controllers and BIOS modules.
For engineers reviewing the AT28C040-20BC datasheet, AT28C040-20BC pinout, AT28C040-20BC application, or AT28C040-20BC equivalent, key selection criteria include JEDEC byte-wide pinout compatibility, DATA polling/Toggle Bit write completion detection, 10,000-cycle endurance, and VCC-sense write inhibit for power-transition safety.
Technical Context
The AT28C040-20BC implements a CMOS-based paged EEPROM architecture with an internal 256-byte page register and autonomous control timer. Read operations emulate static RAM timing with dual-line CE/OE control, while write cycles are initiated by WE or CE edge-triggered latching of address and data.
It features two real-time write completion detection methods: DATA polling on I/O7 (complement-to-true transition) and Toggle Bit behavior on I/O6. Hardware protection includes VCC sense (<3.8V inhibition), 5 ms power-on delay, noise filtering (<15 ns pulse rejection), and multi-level write inhibit logic.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 Mbit (524,288 × 8 bits); supports full memory mapping without bank switching |
| Read Access Time | 200 ns max; enables direct replacement of SRAM in legacy 8-bit bus systems |
| Page Write Cycle | 10 ms max per 1–256 bytes; reduces firmware update latency vs. byte-by-byte programming |
| Endurance | 10,000 write/erase cycles; sufficient for field-upgradable boot code with infrequent updates |
| Data Retention | 10 years at 25°C; validated for long-life industrial control and telecom infrastructure |
| Supply Voltage | 5V ±10%; eliminates need for dedicated voltage regulators in 5V-only designs |
| Operating Temp | 0°C to 70°C; qualified for commercial-grade computing and peripheral applications |
Pinout & Package
AT28C040-20BC is housed in a 44-pad ceramic leadless chip carrier (LCC), JEDEC MO-115 compliant, with side-brazed construction and no window. Pin 1 is marked by a dot; package is non-hermetic unless specified otherwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A18 | Address Inputs | 19-bit address bus supporting full 512K-word addressing; A8–A18 define page boundaries for 256-byte writes |
| I/O0–I/O7 | Bidirectional Data Bus | CMOS/TTL-compatible 8-bit data path; I/O7 used for DATA polling, I/O6 for Toggle Bit detection |
| CE | Chip Enable | Active-low global device select; must be low with OE low for read, or low with WE low for write |
| OE | Output Enable | Active-low output gate; high-Z state prevents bus contention during standby or write cycles |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; high during read or standby |
| VCC | Power Supply | +5V ±10% main supply; powers core logic and charge pumps for write/erase |
| VSS | Ground | Reference return path for all I/O and internal circuitry; decoupling required near pin |
| NC | No Connect | Unbonded pads (e.g., pins 5, 11–13, 16, 24–27, 31, 33–36, 39–41); must remain unconnected |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internal 256-byte latch + timer frees address/data bus after initial load-enables background processing during write |
| DATA Polling & Toggle Bit | Dual, software-transparent write completion signals eliminate need for fixed delays or external status hardware |
| Hardware Write Protection | VCC sense + 5 ms power-on delay + noise filtering prevent spurious writes during brown-out or EMI events |
| Software Data Protection (SDP) | User-configurable 3-byte command sequence enables/disables write access without hardware modification |
| Device Identification Area | 256-byte reserved sector (7FF80H–7FFFFH) accessible via 12V on A9 for serialization or calibration data storage |
Applications
| BIOS/UEFI Firmware Storage | Industrial PLC Configuration Memory |
|---|---|
Use Scenario: Storing boot firmware and hardware initialization code in x86-based motherboards and embedded controllers. IC Role / Device Role / Timing Role: Nonvolatile program memory accessed as memory-mapped ROM during power-on reset sequence. Use Value: 200 ns read speed ensures zero-wait-state execution from reset vector; page write enables fast BIOS updates without full chip erase. |
Use Scenario: Retaining user-defined ladder logic parameters, I/O mapping, and calibration coefficients in programmable logic controllers. IC Role / Device Role / Timing Role: Field-updatable configuration store with guaranteed 10-year data retention under thermal cycling. Use Value: Hardware write protection prevents corruption during power loss; SDP allows secure remote reconfiguration via HMI interface. |
| Network Equipment Bootloader | Medical Device Calibration Storage |
Use Scenario: Holding bootloader images and FPGA configuration bitstreams in switches, routers, and base station radios. IC Role / Device Role / Timing Role: Primary boot source mapped to CPU address space; supports in-system programming over JTAG or UART. Use Value: JEDEC byte-wide pinout ensures drop-in compatibility with legacy SRAM-based boot designs; 10,000-cycle endurance supports frequent firmware patches. |
Use Scenario: Storing sensor calibration constants, usage logs, and regulatory compliance data in diagnostic imaging and infusion pumps. IC Role / Device Role / Timing Role: Tamper-resistant nonvolatile memory with traceable write history and voltage-monitored write enable. Use Value: VCC-sense and software protection meet IEC 62304 Class B requirements; 12V-programmable ID area supports unique device serialization. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar paged parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ST M48T02-200PC1 | Real-time clock + 2 Kbit NV SRAM; no page write; 200 ns read; 5V only | Time-stamped logging instead of firmware storage; lacks DATA polling and SDP | Select when RTC functionality is required alongside small nonvolatile storage |
| Microchip 25LC1024-I/P | 1 Mbit SPI EEPROM; 5 ms page write; 2.5–5.5V supply; no parallel bus | Requires SPI controller interface; lower density but wider voltage range and smaller footprint | Select for space-constrained designs where serial interface is acceptable and 512K×8 is oversized |
Compared with ST M48T02-200PC1 and Microchip 25LC1024-I/P, the AT28C040-20BC delivers higher density, parallel bus compatibility, and robust write-integrity features essential for boot-critical firmware-making it optimal for legacy 8-bit/16-bit microprocessor systems requiring direct memory-mapped access.
Availability
AT28C040-20BC is available at Aetrix Electronics and suitable for BIOS firmware storage, industrial PLC configuration, and network equipment bootloader applications requiring stable component supply across extended production lifecycles.
Supply support for AT28C040-20BC 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 security ICs for embedded systems.
The AT28C040 product line was designed for high-reliability, pin-compatible replacement of EPROM and battery-backed SRAM in legacy computing and industrial control platforms requiring field-upgradable nonvolatile storage.
FAQ
What is the maximum operating temperature range for the AT28C040-20BC?
The AT28C040-20BC is rated for commercial operation from 0°C to 70°C. Its ordering code suffix "BC" explicitly denotes this temperature grade. Industrial variants (e.g., AT28C040-20BI) extend to –40°C to +85°C, but the AT28C040-20BC itself is not qualified beyond 70°C ambient case temperature.
Does the AT28C040-20BC support true simultaneous read/write operations?
No, the AT28C040-20BC does not support concurrent read and write. During a write cycle-including page write-the device enters a busy state where read attempts return polling responses (I/O7 complement or I/O6 toggle) until completion. The AT28C040-20BC requires sequential access: reads must wait for write cycles to finish, verified via DATA polling or Toggle Bit.
How is the 256-byte page boundary determined in the AT28C040-20BC?
In the AT28C040-20BC, the 256-byte page is defined by address bits A8 through A18. All bytes written in a single page write operation must share identical values on these 11 address lines. A0–A7 select the specific byte offset within that page. This constraint ensures internal latching and timing integrity during the 10 ms auto-write cycle.
Can the AT28C040-20BC be used with a 3.3V microcontroller interface?
The AT28C040-20BC requires a 5V ±10% supply and has TTL/CMOS-compatible inputs, but its outputs swing to VCC (5V). Direct connection to a 3.3V-only microcontroller risks overvoltage damage to input pins. Level-shifting circuitry or a 5V-tolerant MCU is required; the AT28C040-20BC itself does not support 3.3V operation.
What happens if the software data protection (SDP) is enabled on the AT28C040-20BC?
When SDP is enabled on the AT28C040-20BC, all write operations-including byte and page writes-are blocked unless preceded by the exact 3-byte command sequence (AAh→55h→A0h to addresses 5555h→2AAAh→5555h). Reads remain fully functional. SDP persists across power cycles and must be explicitly disabled using the corresponding disable sequence (AAh→55h→80h→AAh→20h).
AT28C040-20BC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-CDIP (0.600", 15.24mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 4Mbit
- Memory Organization:
- 512K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 200 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 32-CDIP
AT28C040-20BC FAQ
1.How can I place an order for AT28C040-20BC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C040-20BC 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 AT28C040-20BC reliable?
The price and inventory of AT28C040-20BC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C040-20BC is usually 5 days.
3.What payment methods are accepted for AT28C040-20BC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C040-20BC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C040-20BC?
AT28C040-20BC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C040-20BC 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 AT28C040-20BC?
For technical support, including AT28C040-20BC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C040-20BC requirements.
6.How does Aetrix verify that AT28C040-20BC is sourced from the original manufacturer or authorized distributors?
All AT28C040-20BC 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 AT28C040-20BC meets industry standards.
7.What is the process for return or replacement of AT28C040-20BC?
All AT28C040-20BC units undergo pre-shipment inspection (PSI). If there is an issue with AT28C040-20BC, 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 AT28C040-20BC part is unused and in its original packaging.
Return procedure for AT28C040-20BC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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