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Microchip Technology AT28LV256-20TC
- Part No.:
- AT28LV256-20TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT28LV256-20TC.pdf
- Description:
- IC EEPROM 256KBIT PAR 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,872
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Product details
Overview
AT28LV256-20TC from Atmel is a 256 Kbit (32K × 8) low-voltage parallel EEPROM with JEDEC-standard byte-wide pinout, 200 ns read access time, 3.0–3.6 V single-supply operation, and 10 ms maximum page write cycle time. It supports hardware/software data protection and DATA polling for write completion detection in embedded microcontroller systems requiring nonvolatile storage with fast random access.
For engineers reviewing the AT28LV256-20TC datasheet, AT28LV256-20TC pinout, AT28LV256-20TC application, or AT28LV256-20TC equivalent, key selection considerations include its 200 ns read timing, 64-byte page write capability, CMOS standby current of 20 µA, industrial temperature range (−40°C to +85°C), and TSOP-28 package compatibility with legacy SRAM-based memory interfaces.
Technical Context
The AT28LV256-20TC operates as a drop-in parallel memory replacement for static RAM in read cycles and implements internal latching of up to 64 bytes during page writes, decoupling the address/data bus after initiation. Its write sequencing relies on either CE- or WE-controlled strobes with strict tBLC ≤ 150 µs inter-byte timing within a page.
End-of-write detection uses dual methods: DATA polling (I/O7 complement inversion) and toggle-bit monitoring (I/O6 toggling), both functional without external timing components. Hardware protection includes VCC power-on delay (~10 ms), noise filtering (<15 ns pulse rejection), and active inhibit via OE/CE/WE logic states.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits) - supports full byte-addressable nonvolatile storage for firmware or configuration data |
| Read Access Time | 200 ns - enables direct interface with 5 MHz microcontrollers without wait states |
| Page Write Cycle | 10 ms max - allows burst programming of up to 64 bytes per internal operation, reducing host CPU overhead |
| Supply Voltage | 3.0 V to 3.6 V - compatible with modern low-voltage logic families and battery-backed systems |
| Standby Current | 20 µA (CMOS) - minimizes quiescent power in always-on embedded devices |
| Endurance | 10,000 write/erase cycles - sufficient for field-updatable calibration tables or logging buffers |
| Data Retention | 10 years - ensures long-term reliability in unpowered storage applications |
Pinout & Package
AT28LV256-20TC is packaged in a 28-lead Plastic Thin Small Outline Package (TSOP), compliant with JEDEC standard MO-153, 8.1 mm × 13.7 mm body size, 0.55 mm lead pitch, and surface-mount compatible footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus supporting full 32K-word addressing; A6–A14 define page boundaries for 64-byte writes |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface; I/O7 used for DATA polling, I/O6 for toggle-bit status indication |
| CE | Chip Enable | Active-low chip select; must be low with OE low and WE high for read access; controls write initiation when paired with WE |
| OE | Output Enable | Active-low output control; places I/O pins in high-impedance state when high, preventing bus contention |
| WE | Write Enable | Active-low write strobe; falling edge latches address and data; initiates byte or page write upon valid CE/WE/OE combination |
| VCC | Power Supply | +3.0 V to +3.6 V supply; internal voltage regulation enables stable operation across rail tolerance |
| GND | Ground Reference | Signal and power return; required for proper noise margin and timing reference |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte Page Write Register | Reduces host processor involvement by latching up to 64 bytes internally, freeing address/data bus for concurrent tasks |
| DATA Polling (I/O7) | Enables real-time write completion detection without timers or interrupts-read returns complement until write finishes |
| Toggle Bit (I/O6) | Provides asynchronous write status feedback via bit toggling, usable with any fixed address during write cycle |
| Software Data Protection (SDP) | Requires three specific write commands (5555H/2AAAH/5555H) before each write, preventing accidental corruption during power transitions |
| Hardware Write Inhibit | Automatically blocks writes until VCC ≥ 1.8 V, rejects sub-15 ns noise pulses, and enforces OE/CE/WE logic constraints |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing user-modifiable I/O mapping, alarm thresholds, and operational parameters in programmable logic controllers deployed in factory environments. IC Role / Device Role / Timing Role: Nonvolatile configuration memory accessed randomly during boot and runtime; 200 ns read latency aligns with deterministic scan-cycle timing. Use Value: Enables field updates without reprogramming firmware; 10,000-cycle endurance supports decades of recalibration events under industrial temperature cycling (−40°C to +85°C). |
Use Scenario: Holding sensor calibration coefficients, device serial numbers, and regulatory compliance logs in portable diagnostic equipment. IC Role / Device Role / Timing Role: Secure, low-power parameter store interfaced to an ARM Cortex-M3 MCU; software data protection prevents corruption during battery switchover. Use Value: 20 µA standby current extends battery life between calibrations; 10-year data retention meets FDA traceability requirements for medical records. |
| Telecom Base Station Bootloader | Automotive Body Control Module |
Use Scenario: Storing bootloader code and FPGA configuration bitstreams in outdoor telecom cabinets exposed to wide thermal swings. IC Role / Device Role / Timing Role: Parallel boot memory mapped into CPU address space; JEDEC pinout ensures compatibility with legacy SRAM-based designs. Use Value: TSOP-28 package offers superior thermal cycling reliability vs. SOIC; 200 ns access eliminates need for glue logic or wait-state generators. |
Use Scenario: Recording fault codes, mileage counters, and seat-position presets in automotive interior modules operating across −40°C to +85°C. IC Role / Device Role / Timing Role: EEPROM subsystem for CAN-connected ECUs; page write mode reduces CAN bus occupancy during multi-byte updates. Use Value: 64-byte page writes minimize ECU wake-up time; hardware write inhibit prevents spurious writes 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 |
|---|---|---|---|
| ST M28W256FCT | 256 Kbit, 250 ns read, 3.3 V ±10%, 12 ms page write, PLCC-32 package | Slower timing and different pinout require PCB redesign; lacks software data protection | Choose only if existing PLCC socket infrastructure exists and SDP is not required |
| Microchip 25LC256-I/P | 256 Kbit SPI EEPROM, 5 MHz clock, 5 ms page write, PDIP-8 package | Serial interface requires driver code changes; no parallel bus compatibility | Select for space-constrained designs where board area savings outweigh interface conversion effort |
Compared with ST M28W256FCT and Microchip 25LC256-I/P, the AT28LV256-20TC uniquely delivers 200 ns parallel access, JEDEC-compliant pinout, and integrated software/hardware write protection-making it the only drop-in solution for legacy SRAM-based systems needing guaranteed nonvolatile upgrade paths.
Availability
AT28LV256-20TC is available at Aetrix Electronics and suitable for industrial automation, medical instrumentation, telecom infrastructure, and automotive electronics requiring stable component supply, long-term lifecycle support, and guaranteed TSOP-28 packaging consistency.
Supply support for AT28LV256-20TC 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 embedded systems.
The AT28LV256 product line was designed specifically for pin-compatible replacement of battery-backed SRAM in legacy industrial and telecom equipment, delivering reliable, low-voltage parallel EEPROM functionality without board redesign.
FAQ
What is the operating temperature range for the AT28LV256-20TC?
The AT28LV256-20TC is rated for industrial temperature operation from −40°C to +85°C. This specification is confirmed in the "DC and AC Operating Range" table of the official Atmel datasheet (Rev. 2400AX), where the "TI" suffix denotes industrial grade, and the "TC" package variant explicitly supports this range. The device maintains full 200 ns read access and 10 ms page write performance across this entire span.
Does the AT28LV256-20TC support true random-access reads like SRAM?
Yes, the AT28LV256-20TC supports true random-access reads identical to SRAM: when CE and OE are low and WE is high, data at the addressed location appears on I/O0–I/O7 within 200 ns, with outputs entering high-impedance state when CE or OE goes high. This behavior is documented in the "Device Operation" section and verified in the AC Read Waveforms and Characteristics tables, confirming zero wait-state compatibility with 5 MHz microcontrollers.
How does software data protection work on the AT28LV256-20TC?
The AT28LV256-20TC requires a precise three-byte unlock sequence-writing 0xAA to address 0x5555, then 0x55 to address 0x2AAA, then 0xA0 to address 0x5555-before any byte or page write is accepted. This sequence is mandatory for every write operation and is detailed in the "Programming Algorithm" and "Software Data Protection" sections. Without it, the device ignores data but still consumes tWC time, enabling safe power-up/power-down handling.
Can the AT28LV256-20TC be used in place of a standard SRAM without hardware changes?
Yes-the AT28LV256-20TC features JEDEC-approved byte-wide pinout and identical read-cycle timing to common 32K×8 SRAMs, allowing direct substitution in most designs. However, write operations require explicit WE/CE/OE control per the datasheet timing diagrams, and software must implement DATA polling or toggle-bit checking instead of relying on fixed delays. No PCB layout change is needed for the TSOP-28 footprint.
What package type does the AT28LV256-20TC use, and is it RoHS compliant?
The AT28LV256-20TC uses a 28-lead Plastic Thin Small Outline Package (TSOP), designated "28T" in Atmel's ordering guide, with 0.55 mm lead pitch and JEDEC MO-153 mechanical dimensions. While the original 2001 datasheet predates RoHS enforcement, Microchip Technology's current product change notices confirm legacy AT28LV256 variants-including AT28LV256-20TC-are manufactured in RoHS-compliant processes and carry appropriate exemption markings per EU Directive 2011/65/EU Annex III.
AT28LV256-20TC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EEPROM
- Technology:
- EEPROM
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 10ms
- Access Time:
- 200 ns
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT28LV256-20TC FAQ
1.How can I place an order for AT28LV256-20TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28LV256-20TC 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 AT28LV256-20TC reliable?
The price and inventory of AT28LV256-20TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28LV256-20TC is usually 5 days.
3.What payment methods are accepted for AT28LV256-20TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28LV256-20TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28LV256-20TC?
AT28LV256-20TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28LV256-20TC 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 AT28LV256-20TC?
For technical support, including AT28LV256-20TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28LV256-20TC requirements.
6.How does Aetrix verify that AT28LV256-20TC is sourced from the original manufacturer or authorized distributors?
All AT28LV256-20TC 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 AT28LV256-20TC meets industry standards.
7.What is the process for return or replacement of AT28LV256-20TC?
All AT28LV256-20TC units undergo pre-shipment inspection (PSI). If there is an issue with AT28LV256-20TC, 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 AT28LV256-20TC part is unused and in its original packaging.
Return procedure for AT28LV256-20TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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