My Inquiry
My Account
Microchip Technology AT28HC256E-12PI
- Part No.:
- AT28HC256E-12PI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT28HC256E-12PI.pdf
- Description:
- IC EEPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,920
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT28HC256E-12PI from Microchip Technology (formerly Atmel) is a 256 Kbit (32K × 8) parallel EEPROM with JEDEC-standard byte-wide pinout, 120 ns maximum access time, industrial temperature range (–40°C to +85°C), and high endurance of 100,000 write cycles. It supports page write (1–64 bytes), DATA polling, and hardware/software data protection for embedded nonvolatile storage in microcontroller-based systems.
For engineers reviewing the AT28HC256E-12PI datasheet, AT28HC256E-12PI pinout, AT28HC256E-12PI application, or AT28HC256E-12PI equivalent, key selection considerations include its 120 ns read timing, 3 mA standby current, 80 mA active current, 5 V ±10% single-supply operation, and compatibility with TTL/CMOS buses in legacy and industrial control designs.
Technical Context
The AT28HC256E-12PI implements a CMOS-based parallel EEPROM architecture with internal address/data latching for 64-byte page writes and an autonomous internal control timer. Its dual-line chip enable (CE) and output enable (OE) logic enables bus contention avoidance in multi-device systems.
It features two end-of-write detection methods-DATA polling on I/O7 and toggle-bit monitoring on I/O6-and integrates VCC sense, power-on delay, noise filtering, and software data protection (SDP) to prevent inadvertent writes during power transitions or noise events.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), organized as byte-addressable parallel memory |
| Access Time | 120 ns max - determines minimum read cycle time in synchronous bus interfaces |
| Page Write Time | 10 ms max - defines worst-case latency for 64-byte burst writes |
| Endurance | 100,000 write/erase cycles - validated lifetime for frequent firmware or configuration updates |
| Standby Current | 3 mA max at VCC = 5 V - enables low-power retention in always-on industrial controllers |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation |
| Data Retention | 10 years at 85°C - ensures long-term reliability in unattended equipment |
Pinout & Package
AT28HC256E-12PI is supplied in a 28-lead plastic dual in-line package (PDIP), 0.600" wide (28P6), with JEDEC-standard byte-wide pinout and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus selecting one of 32,768 memory locations |
| I/O0–I/O7 | Bidirectional Data Bus | 8-bit parallel interface for read/write data transfer; TTL/CMOS compatible |
| CE | Chip Enable | Active-low device select; required low with OE low for read or WE low for write |
| OE | Output Enable | Active-low control for output buffer; enables high-impedance state when high |
| WE | Write Enable | Active-low signal initiating byte or page write; latches address/data on falling edge |
| VCC | Power Supply | +5 V ±10% supply; powers core logic and I/O buffers |
| GND | Ground Reference | Common return path for all signals and supply currents |
Key Features
| Feature | Design Value |
|---|---|
| 64-byte Page Write | Reduces firmware update time by up to 64× vs. byte-by-byte writes; requires no external timing control |
| DATA Polling (I/O7) | Enables real-time write completion detection without busy-wait loops or timers |
| Software Data Protection (SDP) | User-configurable lock requiring 3-byte command sequence before each write, preventing accidental overwrites |
| VCC Sense & Power-on Delay | Hardware write inhibition below 3.8 V and 5 ms delay after power-up ensure robustness during brown-out conditions |
| 10-Year Data Retention | Validated at 85°C - supports long-life deployments in sealed or thermally constrained enclosures |
Applications
| Industrial PLC Configuration Storage | Medical Device Calibration Data |
|---|---|
Use Scenario: Storing user-modifiable I/O mapping, PID tuning parameters, and alarm thresholds in programmable logic controllers. IC Role / Device Role / Timing Role: Nonvolatile configuration register accessed via parallel bus during boot or runtime reconfiguration. Use Value: 100K endurance supports field recalibration over 10+ years; 120 ns access enables fast parameter recall during scan cycles. | Use Scenario: Holding factory-calibrated sensor offsets, gain coefficients, and safety-critical operational limits in diagnostic imaging equipment. IC Role / Device Role / Timing Role: Secure, tamper-resistant calibration memory with software/hardware write protection. Use Value: SDP prevents unauthorized modification; 10-year retention guarantees accuracy across service intervals without recalibration. |
| Avionics System Bootloader Storage | Telecom Line Card Firmware Patching |
Use Scenario: Storing bootloader code and secure boot keys in airborne computing modules operating across –40°C to +85°C. IC Role / Device Role / Timing Role: Radiation-tolerant (via ceramic/PDIP packaging) nonvolatile memory for critical startup sequences. Use Value: Industrial temp grade and 3 mA standby current support cold-soak operation and low-power pre-boot states. | Use Scenario: Enabling field-upgradable firmware patches for carrier-grade DSLAM line cards without full board replacement. IC Role / Device Role / Timing Role: In-system programmable parallel EEPROM interfaced to FPGA or microcontroller host. Use Value: Page write capability allows rapid patch deployment; DATA polling simplifies host-side write sequencing logic. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar parallel EEPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT28HC256-12PI | 10K write cycles (vs. 100K); same speed, package, and voltage | Limited to infrequent configuration updates; unsuitable for dynamic logging | Select only if endurance requirements are ≤10K cycles and cost sensitivity outweighs longevity |
| AT28HC256F-12PI | 3 ms page write time (vs. 10 ms); identical endurance, speed, and package | Reduces firmware update latency in time-critical systems; higher ICC during write | Choose when faster in-field updates are required and thermal/power budget permits higher transient current |
Compared with AT28HC256-12PI, the AT28HC256E-12PI delivers 10× greater endurance for field-updatable systems, while AT28HC256F-12PI trades longer write time for reduced update latency - making the E variant optimal for long-life calibration storage and the F variant better suited for frequent firmware patching.
Availability
AT28HC256E-12PI is available at Aetrix Electronics and suitable for industrial control, medical instrumentation, avionics, and telecom infrastructure requiring stable component supply, long-lifecycle support, and guaranteed traceability.
Supply support for AT28HC256E-12PI 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
Microchip Technology acquired Atmel in 2016 and maintains full support for legacy Atmel parallel EEPROMs, including manufacturing, documentation, and quality assurance.
The AT28HC256 product line was designed for reliable, pin-compatible replacement of EPROM and battery-backed SRAM in industrial and military systems requiring field-programmable nonvolatile storage without external circuitry.
FAQ
What is the maximum access time specification for AT28HC256E-12PI?
The AT28HC256E-12PI has a maximum address-to-output delay (tACC) of 120 ns, as indicated by the "-12" suffix in the part number. This value is guaranteed across the full industrial temperature range (–40°C to +85°C) and applies to both CE-controlled and OE-controlled read operations under standard load conditions (CL = 5 pF). The 120 ns timing enables integration into 8 MHz bus systems with adequate setup/hold margins.
Does AT28HC256E-12PI support page write operations, and what is the maximum page size?
Yes, AT28HC256E-12PI supports page write operations with a maximum page size of 64 bytes. The device includes an internal 64-byte page register that latches address and data automatically, allowing sequential writes within 150 µs (tBLC) per byte. All addresses in a single page write must share the same A6–A14 bits, while A0–A5 select individual bytes within the page - enabling efficient firmware or configuration block updates without external buffering.
How does software data protection (SDP) work on AT28HC256E-12PI?
AT28HC256E-12PI implements software data protection (SDP) via a three-byte unlock sequence written to specific addresses (0x5555, 0x2AAA, 0x5555) followed by a protected write command. Once enabled, SDP remains active across power cycles until explicitly disabled using a separate five-byte disable sequence. While SDP is active, any write attempt without the unlock prefix triggers internal timers but writes no data - ensuring configuration integrity in unattended systems.
What package type and pin count does AT28HC256E-12PI use?
AT28HC256E-12PI uses a 28-lead plastic dual in-line package (PDIP), designated as 28P6 in Microchip's ordering nomenclature. It measures 0.600" wide with 0.100" lead pitch, features through-hole mounting, and conforms to JEDEC MS-011AB standards. The package includes standard power (VCC, GND), control (CE, OE, WE), 15 address (A0–A14), and 8 data (I/O0–I/O7) pins - matching industry-standard parallel EEPROM footprints.
Is AT28HC256E-12PI compatible with TTL and CMOS logic levels?
Yes, AT28HC256E-12PI features TTL- and CMOS-compatible inputs and outputs. Input thresholds meet VIH ≥ 2.0 V and VIL ≤ 0.8 V, while outputs drive VOH ≥ 2.4 V at –4 mA and VOL ≤ 0.45 V at 6 mA - satisfying both TTL and CMOS interface requirements. This dual compatibility allows direct connection to legacy 8051/8086 microcontrollers, modern FPGAs, and mixed-voltage system buses without level-shifting circuitry.
AT28HC256E-12PI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-DIP (0.600", 15.24mm)
- Packaging:
- Tube
- 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:
- 120 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT28HC256E-12PI FAQ
1.How can I place an order for AT28HC256E-12PI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT28HC256E-12PI 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 AT28HC256E-12PI reliable?
The price and inventory of AT28HC256E-12PI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT28HC256E-12PI is usually 5 days.
3.What payment methods are accepted for AT28HC256E-12PI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT28HC256E-12PI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT28HC256E-12PI?
AT28HC256E-12PI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT28HC256E-12PI 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 AT28HC256E-12PI?
For technical support, including AT28HC256E-12PI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT28HC256E-12PI requirements.
6.How does Aetrix verify that AT28HC256E-12PI is sourced from the original manufacturer or authorized distributors?
All AT28HC256E-12PI 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 AT28HC256E-12PI meets industry standards.
7.What is the process for return or replacement of AT28HC256E-12PI?
All AT28HC256E-12PI units undergo pre-shipment inspection (PSI). If there is an issue with AT28HC256E-12PI, 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 AT28HC256E-12PI part is unused and in its original packaging.
Return procedure for AT28HC256E-12PI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT28HC256E-12PI Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
