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Microchip Technology AT28C040-25LC
- Part No.:
- AT28C040-25LC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 44-CLCC
- Datasheet:
-
AT28C040-25LC.pdf
- Description:
- IC EEPROM 4MBIT PARALLEL 44CLCC
- Quantity:
- Payment:
- Shipping:
Inventory:3,841
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Product details
Overview
AT28C040-25LC from Atmel is a 4-Mbit (512K × 8) paged parallel EEPROM with JEDEC byte-wide pinout, 250 ns read access time, and 10 ms maximum page write cycle time. It operates on single 5V ±10% supply, supports hardware/software data protection, and is used in firmware storage, configuration memory, and boot code retention for industrial controllers and telecom line cards.
For engineers reviewing the AT28C040-25LC datasheet, AT28C040-25LC pinout, AT28C040-25LC application, or AT28C040-25LC equivalent, key selection criteria include page-write capability (256-byte latching), DATA polling via I/O7, VCC sense-based write inhibit, 10,000-cycle endurance, and LCC-44 ceramic package compatibility with high-reliability embedded systems.
Technical Context
The AT28C040-25LC implements a CMOS-based paged architecture with internal 256-byte address/data latches and an autonomous control timer for self-timed writes. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in shared-memory systems.
Write operations support both byte and page modes: page writes require A8–A18 stable across successive WE transitions, while DATA polling (I/O7 complement toggle) and TOGGLE BIT (I/O6 oscillation) provide real-time write completion detection without external timing components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 4 Mbit (524,288 × 8 bits); supports full system firmware image storage in space-constrained designs |
| Read Access Time | 250 ns max; compatible with 4 MHz bus timing in legacy microcontroller interfaces |
| Page Write Cycle | 10 ms max for up to 256 bytes; reduces firmware update latency vs. byte-by-byte programming |
| Endurance | 10,000 write/erase cycles; suitable for field-upgradable systems requiring moderate reprogramming frequency |
| Data Retention | 10 years at 85°C; validated for industrial temperature range operation without refresh |
| Supply Voltage | 5V ±10%; eliminates need for dedicated voltage regulators in 5V-only systems |
| Operating Temp | -40°C to +85°C (Industrial grade); qualified for deployment in base station power modules and motor drives |
Pinout & Package
AT28C040-25LC uses a 44-pad ceramic leadless chip carrier (LCC) package per JEDEC MO-115/MIL-STD-1835 C-5, with side-braze construction and no window. Pin 1 is marked by a dot; package is non-hermetic but qualified for extended industrial reliability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A18 | Address Inputs | 19-bit address bus supporting full 524,288-word addressing; A8–A18 define page boundaries for write operations |
| 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 status monitoring |
| CE | Chip Enable | Active-low device select; must be low with OE low and WE high for read access; inhibits writes when high |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high to prevent bus conflicts |
| WE | Write Enable | Active-low write strobe; falling edge latches address/data; combined with CE for robust write initiation |
| VCC | Power Supply | +5V ±10% main supply; powers core logic and I/O buffers; VCC sense circuit disables writes below ~3.8V |
| VSS | Ground | Reference return for all signals and power; requires low-inductance connection to minimize noise during page writes |
| NC | No Connect | Unbonded pads (e.g., pins 5, 11–13, 25–28, 36–39); must remain unconnected to avoid parasitic coupling or latch-up |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Page Write | Internally latches 1–256 bytes with autonomous timing-eliminates external write controllers and simplifies host firmware |
| DATA Polling (I/O7) | Real-time write completion signal via complemented data output-enables deterministic polling without fixed delays |
| Hardware Write Inhibit | VCC sense + 5 ms power-on delay + noise filtering (<15 ns pulses rejected)-prevents spurious writes during power ramp |
| Software Data Protection | User-configurable 3-byte command sequence (AAh/55h/A0h) to enable/disable write lock-supports secure field updates |
| Device Identification Area | Dedicated 256-byte EEPROM region (7FF80H–7FFFFH) accessible with A9 = 12V-enables unique device serialization |
Applications
| Industrial PLC Configuration Storage | Telecom Line Card Boot Memory |
|---|---|
Use Scenario: Storing user-defined I/O mapping tables and calibration coefficients in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed during power-up initialization and runtime parameter updates via RS-485 interface. Use Value: 10,000-cycle endurance and 10-year data retention ensure reliable operation over 15+ year equipment lifecycles without battery backup. | Use Scenario: Holding boot firmware and FPGA configuration bitstreams in carrier-grade DSLAM line cards operating in temperature-controlled central offices. IC Role / Device Role / Timing Role: Primary boot ROM interfaced directly to Motorola 68K or ARM7TDMI processors using standard parallel bus protocol. Use Value: 250 ns read access meets tight timing budgets of 4 MHz processor buses; page write reduces firmware upgrade time by 90% vs. byte mode. |
| Medical Imaging System Calibration Data | Avionics Display Module Settings |
Use Scenario: Retaining gamma correction tables and sensor offset values in portable ultrasound machines subject to frequent power cycling and thermal stress. IC Role / Device Role / Timing Role: High-reliability data vault accessed only during service mode via JTAG debug port; write-protected during normal operation. Use Value: Hardware VCC-sense and software data protection prevent accidental corruption during brown-out conditions or firmware upload errors. | Use Scenario: Storing display brightness profiles, language preferences, and fault history logs in cockpit multifunction displays certified to DO-254 Level A. IC Role / Device Role / Timing Role: Safety-critical configuration memory with dual verification: DATA polling confirms write integrity, and device ID area stores traceable manufacturing data. Use Value: Ceramic LCC-44 package withstands 2000g shock and -55°C to +125°C extended temperature qualification per MIL-STD-883. |
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 | 2-Mbit (256K × 8), 200 ns access, built-in lithium battery for RTC + SRAM; no page write | Targets real-time clock + NVRAM combo use cases; lacks 4-Mbit density and automatic page latching | Select when integrated timekeeping is required and firmware size fits within 2 Mbit |
| Microchip 25LC1024-I/P | 1-Mbit SPI EEPROM, 5 ms write time, 1 MHz interface; serial protocol, no parallel bus | Suitable for low-pin-count MCU designs; incompatible with parallel address/data bus architectures | Choose for cost-sensitive, space-constrained applications where SPI interface is already used |
Compared with ST M48T02-200PC1 and Microchip 25LC1024-I/P, the AT28C040-25LC delivers higher density, faster parallel read throughput, and true paged write automation-making it optimal for legacy 8-bit/16-bit microprocessor systems requiring direct memory-mapped firmware storage.
Availability
AT28C040-25LC is available at Aetrix Electronics and suitable for industrial PLCs, telecom line cards, medical imaging subsystems, and avionics display modules requiring stable component supply across extended product lifecycles.
Supply support for AT28C040-25LC 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) was a U.S.-based semiconductor company specializing in microcontrollers, nonvolatile memory, and security ICs, known for high-reliability industrial and automotive products.
The AT28C040 belongs to Atmel's parallel EEPROM product line designed for direct bus interface in legacy embedded systems requiring fast, paged, and highly reliable nonvolatile storage without external timing logic.
FAQ
What is the maximum page write size supported by the AT28C040-25LC?
The AT28C040-25LC supports page write operations of 1 to 256 bytes per internal programming cycle. This is enabled by its internal 256-byte address/data latch, allowing the host to stream up to 256 bytes consecutively within 150 µs intervals before the device initiates autonomous programming. The AT28C040-25LC does not support larger page sizes or partial-page writes outside this boundary.
How does DATA polling work on the AT28C040-25LC during a write cycle?
During a write cycle, reading the last written byte from the AT28C040-25LC returns the bitwise complement of that data on I/O7 until programming completes. Once valid data appears on I/O7, the write cycle is finished. This mechanism allows the host to poll I/O7 without fixed timeouts-critical for deterministic firmware updates. The AT28C040-25LC guarantees this behavior across its full industrial temperature range.
Is the AT28C040-25LC pin-compatible with other 44-pin LCC EEPROMs like the AT28C256?
No, the AT28C040-25LC is not pin-compatible with AT28C256 or other 44-pin LCC EEPROMs. While both use LCC-44 packages, the AT28C040-25LC has 19 address lines (A0–A18) and distinct NC pin placements (e.g., pins 5, 11–13), whereas AT28C256 uses only 15 address lines (A0–A14). Direct replacement would require PCB layout changes and firmware address remapping.
What voltage level is required on A9 to access the device identification area in the AT28C040-25LC?
To access the 256-byte device identification area (addresses 7FF80H–7FFFFH) in the AT28C040-25LC, A9 must be raised to 12V ± 0.5V. This elevated voltage enables a separate memory segment independent of main array operations. Standard 5V operation is used for all other reads/writes. The AT28C040-25LC datasheet specifies strict timing and voltage tolerances for this mode to prevent damage.
Does the AT28C040-25LC support chip erase, and if so, how is it performed?
Yes, the AT28C040-25LC supports optional software chip erase using a 6-byte command sequence detailed in Atmel's Software Chip Erase application note. Unlike page or byte writes, chip erase clears the entire 4-Mbit array. The AT28C040-25LC requires specific address/data patterns and precise timing-no hardware erase pin is provided, and the operation is fully software-controlled and nonvolatile.
AT28C040-25LC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 44-CLCC
- 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:
- 250 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 44-CLCC (16.55x16.55)
AT28C040-25LC FAQ
1.How can I place an order for AT28C040-25LC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28C040-25LC 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 AT28C040-25LC reliable?
The price and inventory of AT28C040-25LC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28C040-25LC is usually 5 days.
3.What payment methods are accepted for AT28C040-25LC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28C040-25LC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28C040-25LC?
AT28C040-25LC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28C040-25LC 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 AT28C040-25LC?
For technical support, including AT28C040-25LC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28C040-25LC requirements.
6.How does Aetrix verify that AT28C040-25LC is sourced from the original manufacturer or authorized distributors?
All AT28C040-25LC 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 AT28C040-25LC meets industry standards.
7.What is the process for return or replacement of AT28C040-25LC?
All AT28C040-25LC units undergo pre-shipment inspection (PSI). If there is an issue with AT28C040-25LC, 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 AT28C040-25LC part is unused and in its original packaging.
Return procedure for AT28C040-25LC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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