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Microchip Technology AT27C256R-15RI
- Part No.:
- AT27C256R-15RI
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-15RI.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,915
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Product details
Overview
AT27C256R-15RI from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM used for firmware storage in microprocessor systems, featuring 45 ns read access time, 5V ±10% supply operation, and industrial temperature range (–40°C to +85°C) in 28-lead SOIC package.
For engineers reviewing the AT27C256R-15RI datasheet, AT27C256R-15RI pinout, AT27C256R-15RI application, or AT27C256R-15RI equivalent, key selection criteria include verified OTP programming compatibility, JEDEC-standard SOIC-28 footprint, 100 µA max standby current, and Rapid™ programming algorithm support at 100 µs/byte.
Technical Context
The AT27C256R-15RI implements a CMOS-based OTP EPROM architecture with dual-line control (CE/OE), enabling bus contention avoidance in embedded systems. It supports standard read modes and rapid programming using VPP = 13.0 V with 100 µs CE pulses, and includes integrated product identification code accessible via A9/VH and A0 toggling.
Its timing behavior is defined by tACC ≤ 150 ns (–15 speed grade), tOE ≤ 40 ns, and tDF ≤ 35 ns, with TTL/CMOS-compatible I/O levels (VIH = 2.0 V min, VOH = 2.4 V min at –400 µA). The device requires external decoupling: 0.1 µF ceramic capacitor per device plus 4.7 µF bulk capacitor for EPROM arrays.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), sufficient for boot code or configuration data in 8-bit microcontroller systems |
| Read Access Time | 150 ns max, ensuring no WAIT states required on 6–7 MHz Z80 or 8086-class processors |
| Supply Voltage | 5V ±10%, compatible with legacy TTL/CMOS logic rails without regulation overhead |
| Standby Current | 100 µA max, enabling low-power retention in battery-backed or intermittent-operation systems |
| Operating Temperature | –40°C to +85°C, qualified for industrial control, motor drives, and instrumentation environments |
| Programming Voltage | VPP = 13.0 V ±0.25 V, requiring dedicated high-voltage programming circuitry or commercial EPROM programmer |
| ESD Protection | 2,000 V HBM, supporting handling in non-ESD-controlled manufacturing and repair workflows |
Pinout & Package
AT27C256R-15RI is packaged in a 28-lead SOIC (package code "R", JEDEC MS-012 AB), 0.330" wide, with gull-wing leads and standard SOIC thermal and mechanical footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 bytes during read or program cycles |
| O0–O7 | Data Outputs | 8-bit bidirectional data path in read mode; high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low chip select; enables memory array only when low, critical for multi-device bus arbitration |
| OE | Output Enable | Active-low output gate; controls data bus drive without disabling internal address decoding |
| VPP | Programming Voltage | 13 V input required only during programming; must be applied simultaneously with or after VCC |
| VCC | Power Supply | +5 V supply; powers logic and memory array; requires local 0.1 µF ceramic decoupling |
| GND | Ground | Reference return for all signals and power; must be low-inductance connection to minimize noise coupling |
| NC | No Connect | Unbonded pins (e.g., Pin 27 in SOIC); must remain unconnected per design specification |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with automatic verify-and-reprogram loop, reducing production burn-in cycle time |
| Integrated Product ID Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle, enabling automated programmer validation |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible bus timing-OE can be delayed up to tACC − tOE without affecting access time |
| JEDEC-Standard Packaging | SOIC-28 footprint matches industry-standard PCB footprints, enabling drop-in replacement across multiple vendors' 256K OTP EPROMs |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V ESD protection ensure robustness in factory handling and field deployment |
Applications
| Industrial PLC Firmware Storage | Legacy PC BIOS Backup |
|---|---|
Use Scenario: Storing ladder logic firmware in programmable logic controllers where field updates are rare but long-term data integrity is critical. IC Role / Device Role / Timing Role: Nonvolatile firmware storage with direct parallel bus interface to 8051 or Z80 derivatives; accessed during cold start and watchdog reset recovery. Use Value: 150 ns access eliminates WAIT state insertion, maintaining deterministic boot timing under full temperature range (–40°C to +85°C). | Use Scenario: Providing fallback BIOS image in early x86 motherboards with dual-ROM redundancy schemes. IC Role / Device Role / Timing Role: Secondary boot ROM mapped to upper memory region; selected via address decoder and enabled only when primary flash fails verification. Use Value: SOIC-28 package allows compact board layout; 100 µA standby current minimizes power draw in always-on backup circuits. |
| Automated Test Equipment Bootloader | Medical Device Configuration Memory |
Use Scenario: Holding self-test routines and calibration constants in benchtop test instruments requiring traceable firmware revision history. IC Role / Device Role / Timing Role: OTP storage for immutable bootloader code executed before loading application firmware from external media. Use Value: Integrated product ID enables automated version verification during manufacturing test, preventing incorrect part loading. | Use Scenario: Storing FDA-mandated device configuration parameters (e.g., alarm thresholds, sensor scaling) in Class II medical electronics. IC Role / Device Role / Timing Role: Secure, write-once parameter store accessed during power-up initialization; isolated from runtime software updates. Use Value: One-time programmability prevents accidental or malicious reconfiguration; 2,000 V ESD rating supports safe handling during clinical service. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-15DC | Same 32K×8 organization, 150 ns access, but uses 28-pin PDIP (not SOIC); higher standby current (200 µA) | Requires PCB redesign for through-hole mounting; lacks SOIC thermal profile for surface-mount assembly lines | Select if legacy through-hole production or socket-based prototyping is required |
| MX27C256-15PC | Identical SOIC-28 package and 150 ns speed grade, but rated only for commercial temp (0°C to +70°C); no automotive/industrial qualification | Not suitable for environments exceeding 70°C ambient or requiring extended temperature validation | Select only for cost-sensitive consumer-grade applications with controlled thermal environments |
Compared with AM27C256B-15DC and MX27C256-15PC, the AT27C256R-15RI uniquely combines industrial temperature rating, SOIC-28 surface-mount compatibility, and 100 µA standby current-making it optimal for volume-manufactured industrial controllers where thermal reliability and assembly efficiency are jointly critical.
Availability
AT27C256R-15RI is available at Aetrix Electronics and suitable for industrial PLCs, legacy computing systems, automated test equipment, and medical device configuration requiring stable component supply across extended lifecycle programs.
Supply support for AT27C256R-15RI 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 memory products including the AT27C256R series.
The AT27C256R product line was designed for reliable, low-cost firmware storage in resource-constrained 8-bit embedded systems where EEPROM endurance or Flash rewrite flexibility is unnecessary.
FAQ
What is the maximum operating temperature range for the AT27C256R-15RI?
The AT27C256R-15RI is rated for industrial temperature operation from –40°C to +85°C. This range is validated per the device's ordering code suffix "I" and confirmed in the AC Operating Conditions table. It ensures reliable read functionality and data retention over the full range without derating. The AT27C256R-15RI does not support automotive (–40°C to +125°C) or extended commercial ranges.
Can the AT27C256R-15RI be programmed in-circuit?
No, the AT27C256R-15RI cannot be reliably programmed in-circuit. Programming requires VPP = 13.0 V ±0.25 V applied to Pin 1, which exceeds standard system rail voltages and risks damaging adjacent components. Atmel specifies use of dedicated EPROM programmers with proper voltage sequencing (VCC applied before VPP). The AT27C256R-15RI is intended for factory-programmed or bench-programmed deployment only.
What is the purpose of the NC pins on the AT27C256R-15RI SOIC package?
The AT27C256R-15RI SOIC package has no NC (No Connect) pins-Pin 27 is designated NC in PLCC and PDIP variants but is assigned to VPP in SOIC. In the 28-lead SOIC (package code "R"), all 28 pins are functional: Pins 1 (VPP), 10 (GND), 28 (VCC), and others as defined in the SOIC top-view diagram. Misidentifying NC pins could lead to incorrect PCB layout; always reference the SOIC-specific pinout in the AT27C256R-15RI datasheet.
How does the Rapid™ Programming Algorithm improve production yield for the AT27C256R-15RI?
The Rapid™ Programming Algorithm improves AT27C256R-15RI production yield by implementing per-byte verification and up to 10 reprogramming attempts before final failure declaration. This reduces false rejects caused by marginal cells or transient noise during programming. Each byte receives a 100 µs CE pulse followed by immediate read-back; only bytes failing verification undergo additional pulses. This targeted approach increases first-pass programming success versus fixed-pulse algorithms, directly lowering scrap rate in high-volume firmware programming.
Is the AT27C256R-15RI pin-compatible with the AT27C256R-15PI?
No, the AT27C256R-15RI is not pin-compatible with the AT27C256R-15PI. While both share identical logic functionality and speed grade (150 ns), they differ in package type: AT27C256R-15RI uses 28-lead SOIC (package code "R"), whereas AT27C256R-15PI uses 28-lead PDIP (package code "P"). Their pinouts are mechanically and electrically incompatible-SOIC has gull-wing leads on 0.050" pitch; PDIP has through-hole leads on 0.600" width. PCB layout and assembly processes are not interchangeable.
AT27C256R-15RI Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-SOIC (0.342", 8.69mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EPROM
- Technology:
- EPROM - OTP
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- -
- Access Time:
- 150 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT27C256R-15RI FAQ
1.How can I place an order for AT27C256R-15RI through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-15RI 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 AT27C256R-15RI reliable?
The price and inventory of AT27C256R-15RI are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-15RI is usually 5 days.
3.What payment methods are accepted for AT27C256R-15RI?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-15RI transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-15RI?
AT27C256R-15RI orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-15RI 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 AT27C256R-15RI?
For technical support, including AT27C256R-15RI datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-15RI requirements.
6.How does Aetrix verify that AT27C256R-15RI is sourced from the original manufacturer or authorized distributors?
All AT27C256R-15RI 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 AT27C256R-15RI meets industry standards.
7.What is the process for return or replacement of AT27C256R-15RI?
All AT27C256R-15RI units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-15RI, 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 AT27C256R-15RI part is unused and in its original packaging.
Return procedure for AT27C256R-15RI:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-15RI 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
Microchip Technology
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24LC01BT-I/OT
Microchip Technology
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
Microchip Technology
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
Microchip Technology
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24AA02UIDT-I/OT
Microchip Technology
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AT24C08C-STUM-T
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