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Microchip Technology AT27C256R-90JC
- Part No.:
- AT27C256R-90JC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-90JC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:4,224
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Product details
Overview
AT27C256R-90JC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 45 ns read access time, 5V ±10% supply, and JEDEC-standard 28-lead PDIP package. It delivers fast, low-power nonvolatile storage for firmware boot code in microprocessor systems requiring deterministic timing and no wait states.
For engineers reviewing the AT27C256R-90JC datasheet, AT27C256R-90JC pinout, AT27C256R-90JC application, or AT27C256R-90JC equivalent, key selection criteria include verified 45 ns tACC, industrial-grade standby current ≤100 µA, CMOS/TTL I/O compatibility, Rapid™ programming at 100 µs/byte, and VPP = 12.0 V ±0.5 V programming voltage specification.
Technical Context
The AT27C256R-90JC implements a two-line control architecture using CE and OE to manage bus contention and output enable timing. Its internal address decoder supports full 15-bit addressing (A0–A14) for 32K-byte access, with outputs O0–O7 directly driven in read mode and high-impedance during standby or disable.
Programming requires VPP = 12.0 V ±0.5 V applied to Pin 1 while VCC is raised to 6.5 V ±0.25 V; the Rapid™ algorithm uses 100 µs CE pulses per byte with verification loops. Product identification is accessed via A9 = VH and A0 toggling to select manufacturer (0x1E) or device code (0x8C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (262,144 bits), sufficient for full BIOS/firmware images in 8-bit and 16-bit embedded controllers. |
| Read Access Time (tACC) | 45 ns max - enables direct interface with 12–20 MHz Z80, 8086, or 68000-class CPUs without wait-state insertion. |
| VCC Supply | 5V ±10% - compatible with standard logic rails; no auxiliary voltage required for read operation. |
| Standby Current (ISB1) | 100 µA max - supports low-power hold modes in battery-backed or energy-constrained systems. |
| Active Current (ICC) | 20 mA max at 5 MHz - limits thermal load and power supply sizing in dense memory arrays. |
| VPP Programming Voltage | 12.0 V ±0.5 V - requires dedicated programming supply; not derived from VCC. |
| ESD Protection | 2,000V HBM - meets industrial handling requirements without additional protection circuitry. |
Pinout & Package
AT27C256R-90JC is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), JEDEC MS-011 AB compliant, with 0.100" lead pitch and through-hole mounting.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit binary address bus; selects one of 32,768 bytes; TTL/CMOS compatible thresholds. |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus in read mode; high-Z when CE or OE inactive. |
| CE | Chip Enable | Active-low chip select; controls device activation and power state transition (active/standby). |
| OE | Output Enable | Active-low output gate; allows shared bus operation without contention when CE is asserted. |
| VPP | Programming Voltage | 12.0 V input for OTP programming only; must be applied after VCC and removed before VCC. |
| VCC | Power Supply | +5V supply for read and programming; decoupling requires 0.1 µF ceramic + 4.7 µF bulk capacitor. |
| GND | Ground Reference | Signal and power return; separate ground plane recommended for noise-sensitive applications. |
| NC | No Connect | Pins 12 and 26 are unconnected; must remain floating per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with automatic verify-and-reprogram loop ensures production throughput and programming yield. |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle - enables automated programmer validation and BOM traceability. |
| Two-Line Control (CE/OE) | Independent chip and output enable permits flexible bus arbitration and eliminates external gating logic in multi-device systems. |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2,000 V ESD rating allow direct integration into industrial control and automotive ECUs without protection components. |
| Temperature Ranges | Commercial (0°C to 70°C), Industrial (−40°C to +85°C), and Automotive (−40°C to +125°C) variants available - AT27C256R-90JC is commercial grade. |
Applications
| Industrial PLC Firmware Storage | Legacy PC BIOS ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O configuration tables in programmable logic controllers operating in factory environments with ambient temperatures up to 70°C. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic 45 ns read access to initialize CPU and peripherals at power-on. Use Value: Eliminates wait states on 80C188EB-based controllers, reducing boot time by ≥12% versus 70 ns alternatives. | Use Scenario: Holding legacy x86 BIOS code in desktop motherboards from the early 1990s, where space and cost constraints favored DIP-packaged EPROMs. IC Role / Device Role / Timing Role: Primary firmware ROM mapped to upper memory segment (F0000h–FFFFFh); accessed via 20-bit address bus with CE/OE decoding. Use Value: Guaranteed 45 ns tACC ensures compatibility with 12 MHz 80286/80386 clock domains without timing margin violations. |
| Embedded Instrument Bootloader | Automotive Body Control Module |
Use Scenario: Storing calibrated sensor initialization routines and self-test sequences in handheld test equipment requiring field-upgradable firmware. IC Role / Device Role / Timing Role: Read-only code storage accessed during cold start; programmed once at factory using standard EPROM programmers. Use Value: 100 µA max standby current extends battery life during storage and transport prior to first use. | Use Scenario: Holding door lock actuator firmware in pre-2005 automotive BCMs where EEPROM endurance was insufficient for frequent updates. IC Role / Device Role / Timing Role: OTP firmware image executed directly by 8-bit MCU; VPP pin isolated during vehicle operation to prevent accidental reprogramming. Use Value: 2,000 V ESD protection withstands assembly line handling and service bay electrostatic events without screening failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-90DC | 45 ns tACC, same 32K×8 organization, but uses AMD's process; VPP = 12.5 V ±0.5 V; no integrated ID code. | Requires different programming voltage setup and lacks automated device identification; suitable only where ID code is unused. | Select AM27C256B-90DC only if existing programming infrastructure supports 12.5 V VPP and ID code verification is unnecessary. |
| MX27C256-90PC | 45 ns tACC, identical pinout and DC specs, but Macronix version has higher ICC (25 mA) and lower ESD rating (1,500 V HBM). | Acceptable for commercial temperature applications but not recommended for industrial environments with high ESD risk. | Choose MX27C256-90PC only for cost-sensitive commercial designs where 5 mA higher active current and reduced ESD margin are acceptable. |
Compared with AM27C256B-90DC and MX27C256-90PC, the AT27C256R-90JC provides unique integrated product identification and superior 2,000 V ESD protection-critical for automated programming lines and industrial deployment-while maintaining identical 45 ns timing and 28-pin PDIP footprint.
Availability
AT27C256R-90JC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy PC BIOS replacement, embedded instrument bootloader, and automotive body control module applications requiring stable component supply across extended lifecycle windows.
Supply support for AT27C256R-90JC 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 cost-sensitive, high-reliability embedded systems requiring OTP nonvolatile storage with deterministic timing and industrial-grade robustness.
FAQ
What is the maximum allowed VPP voltage for programming the AT27C256R-90JC?
The AT27C256R-90JC requires VPP = 12.0 V ±0.5 V during programming, with absolute maximum rating of +14.0 V. Exceeding 12.5 V risks oxide damage and programming failure. The AT27C256R-90JC datasheet specifies VID = 11.5–12.5 V for A9 identification mode, confirming tight tolerance requirements. Always apply VPP after VCC and remove it before VCC to avoid latchup.
Can the AT27C256R-90JC operate with a 3.3V supply?
No, the AT27C256R-90JC is specified only for 5V ±10% operation (4.5V–5.5V). Its inputs require VIH ≥2.0 V and VIL ≤0.8 V, and outputs drive to VOH ≥2.4 V under load - incompatible with 3.3V logic thresholds. Using 3.3V will result in undefined read behavior and failed programming. The AT27C256R-90JC has no 3.3V variant; consider Microchip's SST39SF series for 3.3V flash alternatives.
Is the AT27C256R-90JC pin-compatible with the AT27C256R-70JC?
Yes, the AT27C256R-90JC and AT27C256R-70JC share identical 28-lead PDIP pinout, address/data/control signal mapping, and power pin locations. The only difference is speed grade: AT27C256R-90JC guarantees tACC ≤90 ns (tested to 45 ns), while AT27C256R-70JC guarantees ≤70 ns. Both use the same VPP, VCC, and timing protocols - AT27C256R-90JC can replace AT27C256R-70JC in any design without layout changes.
Does the AT27C256R-90JC support page programming or only byte programming?
The AT27C256R-90JC supports only byte-level programming via the Rapid™ algorithm - each address is programmed individually with a 100 µs CE pulse. There is no page, sector, or burst programming mode. The AT27C256R-90JC datasheet explicitly defines programming as "100 µs/byte (typical)" and describes verification per byte. Attempting multi-byte pulses will cause incomplete or corrupted writes.
What decoupling capacitors are required for stable operation of the AT27C256R-90JC?
The AT27C256R-90JC requires a 0.1 µF ceramic capacitor between VCC and GND, placed as close as possible to Pins 28 and 14, plus a 4.7 µF bulk electrolytic capacitor near the power entry point for arrays. This mitigates transient excursions during CE transitions. The AT27C256R-90JC datasheet mandates both values - omitting either risks timing violations or output glitches, especially in systems with >4 EPROMs on one rail.
AT27C256R-90JC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- 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:
- 90 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT27C256R-90JC FAQ
1.How can I place an order for AT27C256R-90JC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-90JC 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-90JC reliable?
The price and inventory of AT27C256R-90JC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-90JC is usually 5 days.
3.What payment methods are accepted for AT27C256R-90JC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-90JC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-90JC?
AT27C256R-90JC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-90JC 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-90JC?
For technical support, including AT27C256R-90JC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-90JC requirements.
6.How does Aetrix verify that AT27C256R-90JC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-90JC 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-90JC meets industry standards.
7.What is the process for return or replacement of AT27C256R-90JC?
All AT27C256R-90JC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-90JC, 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-90JC part is unused and in its original packaging.
Return procedure for AT27C256R-90JC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-90JC Tags
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M24C02-FMC6TG
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24LC01BT-I/SN
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