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Microchip Technology AT27C256R-70RC
- Part No.:
- AT27C256R-70RC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-SOIC (0.342", 8.69mm Width)
- Datasheet:
-
AT27C256R-70RC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,886
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Product details
Overview
AT27C256R-70RC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM used for nonvolatile firmware storage in microprocessor systems. It delivers 45 ns read access time, operates on a single 5V ±10% supply, and supports industrial temperature range (–40°C to +85°C) in a 28-lead SOIC package.
For engineers reviewing the AT27C256R-70RC datasheet, AT27C256R-70RC pinout, AT27C256R-70RC application, or AT27C256R-70RC equivalent, key selection criteria include verified 70 ns max tACC timing grade, SOIC package compatibility with legacy board layouts, OTP reliability for fixed-code deployment, and dual-line control (CE/OE) for bus contention management.
Technical Context
The AT27C256R-70RC implements a CMOS-based OTP EPROM architecture with address decoding for 32K byte locations (A0–A14), eight bidirectional data outputs (O0–O7), and two active-low control lines (CE, OE). Its Rapid™ programming algorithm enables 100 µs/byte typical write cycles using VPP = 13.0 V during programming.
It features integrated product identification code (Manufacturer ID = 0x1E, Device ID = 0x8C) accessed via A9 high-voltage mode (11.5–12.5 V), and meets JEDEC-standard SOIC packaging requirements with 0.330" body width and gull-wing leads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8 bits (262,144-bit OTP EPROM) |
| Read Access Time (tACC) | 70 ns max - guarantees deterministic timing for 14 MHz Z80/8086 bus interfaces without WAIT states |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails; no auxiliary voltage required in read mode |
| Active Current (ICC) | 20 mA max at 5 MHz - enables low-power operation in embedded controllers with burst read patterns |
| Standby Current (ISB1) | 100 µA max (CMOS CE input) - supports battery-backed retention in low-duty-cycle systems |
| Programming Voltage (VPP) | 13.0 V ±0.25 V - requires dedicated programming hardware; not used during normal read operation |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade PCB environments with thermal cycling |
Pinout & Package
AT27C256R-70RC is packaged in a 28-lead SOIC (Small Outline Integrated Circuit), 0.330" wide, JEDEC MS-012 compliant, with gull-wing surface-mount leads and standard pin pitch of 0.050".
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; selects one of 32,768 memory locations |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus; outputs valid within 70 ns after CE/OE assertion |
| CE | Chip Enable | Active-low global enable; places outputs in high-impedance state when deasserted |
| OE | Output Enable | Active-low output gate; allows shared bus operation without external tri-state logic |
| 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 all internal logic and output drivers during read and standby modes |
| GND | Ground Reference | 0 V reference for all inputs, outputs, and internal circuitry; requires local 0.1 µF ceramic decoupling |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical - reduces firmware burn time by >5× vs. legacy EPROMs, enabling high-throughput production programming |
| Integrated Product ID Code | Manufacturer ID 0x1E + Device ID 0x8C - enables automatic algorithm selection in industry-standard programmers (e.g., Data I/O, BP Microsystems) |
| Two-Line Control Architecture | Separate CE and OE pins - eliminates need for external bus transceivers and simplifies timing-critical microcontroller interfacing |
| ESD & Latchup Robustness | 2,000 V HBM ESD protection and 200 mA latchup immunity - ensures reliability in manual handling and noisy industrial environments |
| JEDEC-Standard SOIC Package | 28-lead, 0.330" wide, gull-wing - provides drop-in replacement capability for legacy 27C256 designs without PCB redesign |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
Use Scenario: Fixed-function programmable logic controller storing ladder logic and I/O mapping tables. IC Role / Device Role / Timing Role: Nonvolatile boot memory holding immutable firmware executed directly by the CPU at power-on reset. Use Value: 70 ns tACC ensures zero-wait-state execution on 80C188EB-based controllers, eliminating timing bottlenecks in real-time scan cycles. | Use Scenario: Embedded system using Z80 or 8086-family CPU requiring reliable cold-start code execution. IC Role / Device Role / Timing Role: Primary boot ROM mapped to low memory space (0x0000–0x7FFF); accessed via parallel address/data bus. Use Value: CMOS/TTL-compatible I/O levels and 20 mA active drive support direct connection to vintage CPU buses without level-shifting or buffering. |
| Medical Device Configuration Memory | Automated Test Equipment (ATE) Pattern ROM |
Use Scenario: Class II medical instrument storing calibration constants and safety-critical operational parameters. IC Role / Device Role / Timing Role: OTP configuration store preventing unauthorized runtime modification; accessed during self-test sequence. Use Value: One-time programmability and 100 µA standby current ensure data integrity and ultra-low power consumption during standby monitoring phases. | Use Scenario: Production test system storing digital stimulus/response vectors for IC functional verification. IC Role / Device Role / Timing Role: High-speed pattern lookup table accessed sequentially by FPGA-based sequencer. Use Value: 70 ns tACC and 20 ns tOE enable sustained 14.3 MHz read throughput, matching ATE timing requirements for sub-100 ns per vector execution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-70RC | Successor revision with identical pinout, timing, and OTP functionality; improved process yield and tighter ICC spec (15 mA max active) | No change in system integration; same PCB footprint and firmware toolchain support | Select for new designs where enhanced manufacturing consistency and marginally lower active power are valued |
| MX27C256-70PC | Pin-compatible 32K×8 OTP EPROM; 70 ns tACC, but uses PDIP package and lacks integrated ID code | Requires through-hole assembly; no automated programmer ID recognition - manual algorithm selection needed | Choose only if PDIP mounting is mandatory and programming infrastructure does not rely on electronic device identification |
Compared with AT27C256R-70RC, AT27C256B-70RC offers higher production yield and lower active current, while MX27C256-70PC sacrifices ID code and package type for cost-sensitive through-hole use - neither is pin-to-pin or functionally identical across all operating modes.
Availability
AT27C256R-70RC is available at Aetrix Electronics and suitable for industrial control, legacy computing, medical instrumentation, and automated test equipment requiring stable component supply over extended production lifecycles.
Supply support for AT27C256R-70RC 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 belongs to Atmel's OTP EPROM family designed for cost-effective, radiation-tolerant, nonvolatile code storage in systems where firmware updates are unnecessary after manufacturing.
FAQ
What is the maximum allowed read access time for AT27C256R-70RC?
The AT27C256R-70RC has a guaranteed maximum address-to-output delay (tACC) of 70 ns under industrial temperature conditions (–40°C to +85°C) and 5V ±10% supply. This value is specified in the AC Characteristics table and applies to all valid combinations of CE and OE assertion. The -70 suffix explicitly denotes this speed grade, distinguishing it from faster (-45, -55) or slower (-90, -12) variants of the AT27C256R family.
Does AT27C256R-70RC require a programming voltage during normal operation?
No, AT27C256R-70RC does not require VPP during normal read or standby operation. VPP = 13.0 V is required only during programming and verification cycles. In read mode, the device operates solely from VCC = 5V ±10%. Applying VPP during read mode may damage the device or cause undefined behavior, as confirmed in the Absolute Maximum Ratings and Operating Modes sections of the datasheet.
Can AT27C256R-70RC be used as a direct replacement for AT27C256R-70PC?
Yes, AT27C256R-70RC can replace AT27C256R-70PC in most applications because both share identical electrical specifications, timing (70 ns tACC), pinout, and OTP functionality. The only difference is package type: RC = SOIC, PC = PDIP. Board-level substitution requires adapting soldering method (SMT vs. through-hole) and verifying mechanical clearance, but no changes to firmware, timing analysis, or schematic design are needed.
What is the purpose of the VPP pin on AT27C256R-70RC?
The VPP pin on AT27C256R-70RC supplies 13.0 V ±0.25 V exclusively during programming and verification operations. It enables Fowler-Nordheim tunneling for oxide breakdown and charge trapping in the floating-gate memory cells. During read mode, VPP must be tied to VCC (5 V) or left unconnected per manufacturer guidance; applying 13 V during read will violate absolute maximum ratings and risk permanent damage to the AT27C256R-70RC.
How is the manufacturer and device identification code accessed on AT27C256R-70RC?
The AT27C256R-70RC identification code is accessed by asserting CE = VIL and OE = VIL while setting A9 = 12.0 V ±0.5 V (VID) and toggling A0 between VIL and VIH. With all other address lines (A1–A14) held low, A0 = VIL returns the Manufacturer ID (0x1E), and A0 = VIH returns the Device ID (0x8C). This feature is used by certified programmers to auto-detect part identity and select correct programming algorithms.
AT27C256R-70RC 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:
- 70 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SOIC
AT27C256R-70RC FAQ
1.How can I place an order for AT27C256R-70RC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70RC 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-70RC reliable?
The price and inventory of AT27C256R-70RC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70RC is usually 5 days.
3.What payment methods are accepted for AT27C256R-70RC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70RC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-70RC?
AT27C256R-70RC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70RC 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-70RC?
For technical support, including AT27C256R-70RC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70RC requirements.
6.How does Aetrix verify that AT27C256R-70RC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70RC 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-70RC meets industry standards.
7.What is the process for return or replacement of AT27C256R-70RC?
All AT27C256R-70RC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70RC, 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-70RC part is unused and in its original packaging.
Return procedure for AT27C256R-70RC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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