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Microchip Technology AT27C256R-55PC
- Part No.:
- AT27C256R-55PC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C256R-55PC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,987
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Product details
Overview
AT27C256R-55PC from Atmel is a 32K × 8-bit one-time programmable EPROM (OTP EPROM) with 45 ns read access time, 5V ±10% supply operation, and JEDEC-standard 28-lead PDIP packaging. It delivers low-power active current (20 mA max at 5 MHz) and standby current (100 µA max), enabling reliable firmware storage in microprocessor-based embedded systems without wait states.
For engineers reviewing the AT27C256R-55PC datasheet, AT27C256R-55PC pinout, AT27C256R-55PC application, or AT27C256R-55PC equivalent, key selection criteria include verified 45 ns tACC timing, VPP programming voltage requirements (12.0 V ±0.5 V), CMOS/TTL I/O compatibility, integrated product identification code support, and industrial temperature range (-40°C to +85°C) compliance.
Technical Context
The AT27C256R-55PC implements a two-line control architecture using Chip Enable (CE) and Output Enable (OE) to manage bus contention and output tri-state behavior. Its internal address decoding supports full 15-bit addressing (A0–A14) for 32K-byte access, with NC pins on PLCC and TSOP variants confirming package-specific pin assignments.
Programming uses Atmel's Rapid™ algorithm requiring 100 µs/byte CE pulses at VPP = 13.0 V ±0.25 V and VCC = 6.5 V ±0.25 V, followed by verify cycles. Product identification is accessed via A9 = VH (12.0 V) and A0 toggling, returning manufacturer ID (0x1E) and device code (0x8C) on O7–O0.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8), supporting full byte-wide data bus interfacing |
| Read Access Time (tACC) | 55 ns max - guarantees sub-18 MHz microprocessor interface without wait states |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails and eliminates need for auxiliary supplies |
| Active Current (ICC) | 20 mA max at 5 MHz - enables low-thermal-load integration in dense PCB layouts |
| Standby Current (ISB1) | 100 µA max (CMOS CE) - supports battery-backed or low-power sleep modes |
| VPP Programming Voltage | 12.0 V ±0.5 V - requires dedicated programming circuitry; not used during normal read operation |
| ESD Protection | 2000 V HBM - ensures robustness during handling and board assembly |
| Latchup Immunity | 200 mA - prevents destructive latchup under transient overvoltage conditions |
Pinout & Package
AT27C256R-55PC is supplied in a 28-lead, 0.600" wide plastic dual inline package (PDIP), per JEDEC MS-011 AB standard. Pin 1 is index-marked; pin 10 is GND and pin 24 is VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; fully decoded to select one of 32,768 bytes |
| O0–O7 | Data Outputs | True TTL/CMOS-compatible 8-bit bidirectional data bus outputs (open-drain not supported) |
| CE | Chip Enable | Active-low global enable; controls device power state and output driver activation |
| OE | Output Enable | Active-low output gate; allows shared bus operation without disabling chip power |
| VPP | Programming Voltage | 12 V input required only during programming; must be applied simultaneously with or after VCC |
| GND | Ground Reference | Pin 10 - primary signal and power return path; decoupling capacitor must connect here |
| VCC | Power Supply | Pin 24 - 5 V ±10% supply; requires 0.1 µF ceramic capacitor placed adjacent to pin |
| NC | No Connect | Pins 12 and 23 are unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with automatic verify/reprogram loop up to 10 pulses per byte |
| Integrated Product Identification Code | Electronic readout of manufacturer ID (0x1E) and device code (0x8C) via A9/A0 control - enables auto-algorithm selection in programmers |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible bus arbitration and partial memory mapping without external logic |
| High-Reliability Process | 2000 V ESD protection and 200 mA latchup immunity ensure field reliability in industrial environments |
| Multi-Temperature Grade Support | Industrial grade (-40°C to +85°C) operation confirmed for AT27C256R-55PC - validated across full AC/DC specs |
Applications
| Industrial PLC Firmware Storage | Legacy Automotive ECU Boot ROM |
|---|---|
Use Scenario: Storing fixed firmware for programmable logic controllers operating in factory-floor environments with ambient temperatures up to +85°C. IC Role / Device Role / Timing Role: Non-volatile boot ROM providing immediate instruction fetch upon power-up with guaranteed 55 ns access to support 16-bit microcontrollers. Use Value: Eliminates reliance on slower serial EEPROM or external flash; avoids wait states and simplifies reset sequencing. | Use Scenario: Holding calibration tables and startup routines in pre-OBD-II engine control units where reprogramming is infrequent and field updates are performed via diagnostic port. IC Role / Device Role / Timing Role: OTP EPROM acting as immutable master code repository; VPP pin isolated during vehicle operation to prevent accidental reprogramming. Use Value: Ensures functional safety integrity by preventing runtime corruption; leverages 200 mA latchup immunity against automotive load-dump transients. |
| Medical Instrument Bootloader | Avionics Display Subsystem ROM |
Use Scenario: Hosting certified bootloader code in Class II medical devices requiring long-term data retention (>20 years) and regulatory traceability. IC Role / Device Role / Timing Role: Secure, one-time-programmable memory storing signed firmware images; accessed only during cold start via dedicated address decode logic. Use Value: Meets IEC 62304 software lifecycle requirements through hardware-enforced immutability and manufacturer ID verification. | Use Scenario: Providing display initialization sequences and font glyphs in ruggedized cockpit displays exposed to extended thermal cycling (-40°C to +85°C). IC Role / Device Role / Timing Role: High-reliability ROM delivering deterministic pixel timing data to display controllers with zero latency variation. Use Value: Guarantees consistent frame initialization under vibration and thermal stress due to 2000 V ESD-hardened I/O and stable tACC performance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-55DC | Same 32K×8 organization and 55 ns speed grade, but uses AMD's process with 10 mA typical active current vs. Atmel's 20 mA max | Lower active power draw suits battery-buffered systems; lacks integrated product ID code | Select AM27C256B-55DC only if system-level programming equipment does not require electronic ID verification |
| MX27C256-55PC | Macronix variant with identical pinout and 55 ns rating, but specifies 150 µA max standby current (vs. 100 µA for AT27C256R-55PC) | Slightly higher leakage may impact ultra-low-power sleep modes; same VPP = 12.5 V requirement | Prefer AT27C256R-55PC when standby current budget is constrained below 120 µA across temperature range |
Compared with AM27C256B-55DC and MX27C256-55PC, the AT27C256R-55PC offers tighter standby current control (100 µA max), built-in product ID for automated programming validation, and documented Rapid™ algorithm compatibility - critical for high-yield production programming.
Availability
AT27C256R-55PC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy automotive ECU boot ROM, and medical instrument bootloader applications requiring stable component supply, long-lifecycle availability, and traceable sourcing.
Supply support for AT27C256R-55PC 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) designed high-reliability non-volatile memory and microcontroller solutions for industrial, automotive, and computing markets before its 2016 acquisition.
The AT27C256R belongs to Atmel's OTP EPROM product line, engineered specifically for cost-sensitive, high-volume embedded systems requiring guaranteed firmware immutability, fast parallel read access, and JEDEC-standard packaging compatibility.
FAQ
What is the maximum allowable VPP voltage for programming the AT27C256R-55PC?
The AT27C256R-55PC 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 reduced data retention. The AT27C256R-55PC datasheet specifies VID (A9 identification voltage) at 11.5–12.5 V, confirming tight tolerance dependency. Always apply VPP simultaneously with or after VCC and remove it simultaneously with or before VCC.
Does the AT27C256R-55PC support read operations at 5.5 V supply?
Yes, the AT27C256R-55PC supports read operations across the full 5 V ±10% range (4.5 V to 5.5 V). All AC characteristics-including tACC = 55 ns max-are guaranteed at 5.5 V. However, VPP programming must still be set to 12.0 V ±0.5 V regardless of VCC level; the AT27C256R-55PC does not support VPP = VCC programming mode during normal read operation.
Can the AT27C256R-55PC be used in place of the AT27C256R-45PC?
No, the AT27C256R-55PC is not a drop-in replacement for the AT27C256R-45PC. While pinout and functionality are identical, the AT27C256R-55PC has a slower maximum access time (55 ns vs. 45 ns), limiting use with microprocessors requiring sub-50 ns memory response. System timing margins must be re-verified; the AT27C256R-55PC is intended for cost-optimized designs where 55 ns suffices.
How is the Integrated Product Identification Code accessed on the AT27C256R-55PC?
The AT27C256R-55PC returns its Manufacturer ID (0x1E) and Device Code (0x8C) when A9 is driven to 12.0 V ±0.5 V (VH), A0 is toggled between VIL and VIH, and all other address lines (A1–A14) are held low. This occurs during a standard read cycle with CE = OE = VIL. The AT27C256R-55PC uses this feature to enable automatic algorithm selection in industry-standard programmers.
What decoupling capacitance is required for stable operation of the AT27C256R-55PC?
The AT27C256R-55PC requires a 0.1 µF high-frequency ceramic capacitor placed between VCC (pin 24) and GND (pin 10), mounted as close as possible to the device. For systems with multiple AT27C256R-55PC devices or large EPROM arrays, a 4.7 µF bulk electrolytic capacitor must also be added between VCC and GND near the power entry point to suppress supply rail droop during simultaneous output transitions.
AT27C256R-55PC 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:
- EPROM
- Technology:
- EPROM - OTP
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- -
- Access Time:
- 55 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
AT27C256R-55PC FAQ
1.How can I place an order for AT27C256R-55PC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-55PC 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-55PC reliable?
The price and inventory of AT27C256R-55PC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-55PC is usually 5 days.
3.What payment methods are accepted for AT27C256R-55PC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-55PC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-55PC?
AT27C256R-55PC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-55PC 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-55PC?
For technical support, including AT27C256R-55PC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-55PC requirements.
6.How does Aetrix verify that AT27C256R-55PC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-55PC 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-55PC meets industry standards.
7.What is the process for return or replacement of AT27C256R-55PC?
All AT27C256R-55PC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-55PC, 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-55PC part is unused and in its original packaging.
Return procedure for AT27C256R-55PC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-55PC Tags
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M24C02-WMN6TP
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AT24C02C-XHM-T
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AT21CS01-STUM10-T
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