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Microchip Technology AT27C256R-12TC
- Part No.:
- AT27C256R-12TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-12TC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,135
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Product details
Overview
AT27C256R-12TC from Microchip Technology (formerly Atmel) is a 256K-bit (32K × 8) one-time programmable EPROM with 45 ns read access time, 5V ±10% supply operation, and JEDEC-standard 28-lead TSOP package. It serves as non-volatile firmware storage in microprocessor systems requiring fast, reliable code execution without wait states.
For engineers reviewing the AT27C256R-12TC datasheet, AT27C256R-12TC pinout, AT27C256R-12TC application, or AT27C256R-12TC equivalent, key selection criteria include verified 45 ns tACC timing, 100 µA max standby current, CMOS/TTL I/O compatibility, Rapid™ programming at 100 µs/byte, and support for commercial temperature range (0°C to 70°C).
Technical Context
The AT27C256R-12TC implements a standard OTP EPROM architecture with dual-line control (CE and OE), enabling bus contention avoidance in shared-data-bus systems. Its address space spans A0–A14 (15 bits), supporting full 32K-byte decoding without external logic.
It uses scaled CMOS technology with 2,000V ESD protection and 200 mA latchup immunity. Programming requires VPP = 12.0 V ±0.5 V and VCC = 6.5 V during write cycles, while read mode operates at standard 5V - eliminating need for auxiliary voltage rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32K × 8); supports full 8-bit data bus interface without byte masking logic |
| Read Access Time (tACC) | 45 ns max; enables direct connection to 22 MHz microprocessors without wait-state insertion |
| Supply Voltage | 5V ±10%; compatible with standard TTL/CMOS logic families and eliminates need for voltage regulators |
| Standby Current (ISB1) | 100 µA max; reduces system power budget in low-duty-cycle embedded controllers |
| Active Current (ICC) | 20 mA max at 5 MHz; allows stable operation under sustained read bursts in real-time firmware fetch |
| Programming Speed | 100 µs/byte typical; cuts firmware update time by >90% vs. legacy EPROM algorithms |
| Operating Temperature | 0°C to 70°C; validated for commercial-grade industrial control panels and instrumentation |
Pinout & Package
AT27C256R-12TC is housed in a 28-lead Thin Small Outline Package (TSOP, Type 1), 8.1 mm × 13.7 mm footprint, 1.2 mm height, compliant with JEDEC MO-153. Pin 1 marked via index notch; pins are gull-wing surface-mount terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus; fully decodes 32K locations; no external address latching required |
| O0–O7 | Data Outputs | True TTL/CMOS-compatible bidirectional outputs; drive standard 5V logic loads directly |
| CE | Chip Enable | Active-low chip select; controls device enable/disable for memory-mapped I/O arbitration |
| OE | Output Enable | Active-low output gate; allows multiple devices on same data bus without contention |
| VPP | Programming Voltage | 12.0 V ±0.5 V input during programming only; must be isolated from 5V rail during read mode |
| VCC | Power Supply | 5V ±10% main supply; powers all internal logic and output drivers during read and program modes |
| GND | Ground Reference | Common return path for VCC and VPP; requires local 0.1 µF ceramic decoupling per device |
| NC | No Connect | Pins 12 and 25 are unconnected; must remain floating - no PCB trace or pull-up/down |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time with auto-verify loop; reduces production programming cycle time by factor of 5 vs. conventional EPROMs |
| Integrated Product Identification Code | Manufacturer ID (0x1E) and Device Code (0x8C) readable via A9/VH and A0 toggle; enables automatic algorithm selection in universal programmers |
| Two-Line Control Architecture | Independent CE and OE inputs allow flexible memory mapping and eliminate bus contention in multi-device systems |
| High-Reliability CMOS Process | 2,000V HBM ESD rating and 200 mA latchup immunity ensure robustness in manual handling and noisy industrial environments |
| JEDEC-Standard Packaging | 28T TSOP package matches industry layout footprints; supports automated SMT assembly without custom tooling |
Applications
| Industrial PLC Firmware Storage | Legacy Embedded System Boot ROM |
|---|---|
Use Scenario: Storing ladder logic firmware in programmable logic controllers where field updates are rare but long-term data retention is critical. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 45 ns instruction fetch timing to CPU during cold start and runtime. Use Value: Eliminates reliance on slower EEPROM or flash; guarantees zero wait-state execution for time-critical scan cycles. | Use Scenario: Replacing obsolete UV-erasable EPROMs in legacy medical diagnostic equipment requiring firmware immutability. IC Role / Device Role / Timing Role: One-time programmable ROM holding BIOS-level initialization routines and calibration constants. Use Value: Provides tamper-proof, radiation-tolerant storage unaffected by ambient light exposure unlike UV EPROMs. |
| Automotive Instrument Cluster Display Code | Test Equipment Microcode Repository |
Use Scenario: Holding display driver microcode in automotive dashboards operating across 0°C to 70°C ambient range. IC Role / Device Role / Timing Role: Read-only memory mapped to MCU's external bus; accessed synchronously during GUI refresh cycles. Use Value: Delivers consistent 45 ns access latency across temperature, preventing frame jitter in analog gauge rendering. | Use Scenario: Storing test pattern generation firmware in automated circuit board testers where firmware changes occur quarterly. IC Role / Device Role / Timing Role: Fixed-function code store interfaced to FPGA-based controller via parallel address/data bus. Use Value: Enables rapid reprogramming via Rapid™ algorithm during factory calibration without changing PCB layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-12DC | Same 256K × 8 organization, 45 ns access, but uses 28-pin PDIP (28P6) instead of TSOP; higher 150 µA standby current | Preferred for through-hole prototyping or legacy repair; not suitable for high-density SMT designs | Select when board layout lacks TSOP footprint or requires hand-soldering capability |
| MX27C256-12QI | Identical 45 ns speed grade and 5V operation, but rated for -40°C to +85°C industrial range; no integrated product ID code | Suitable for extended-temperature deployments where firmware integrity must survive thermal cycling | Choose for new industrial designs requiring wider temp range and accepting loss of auto-programmer ID detection |
Compared with AM27C256B-12DC and MX27C256-12QI, the AT27C256R-12TC uniquely combines TSOP packaging, 100 µA standby, and integrated identification code - making it optimal for cost-sensitive, high-volume commercial SMT applications where programming automation and board space are critical.
Availability
AT27C256R-12TC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy embedded system boot ROM, and automotive instrument cluster display code requiring stable component supply and long-lifecycle availability.
Supply support for AT27C256R-12TC 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. The company specializes in microcontrollers, analog, and non-volatile memory solutions for industrial, automotive, and consumer markets.
The AT27C256R-12TC belongs to Atmel's 27C-series OTP EPROM family, designed specifically for cost-effective, high-reliability firmware storage in systems where code immutability, fast read access, and JEDEC-standard packaging are mandatory.
FAQ
What is the maximum read access time specified for the AT27C256R-12TC?
The AT27C256R-12TC has a maximum read access time (tACC) of 45 ns under standard conditions (VCC = 5V ±10%, TA = 0°C to 70°C). This value is guaranteed across the commercial temperature range and applies to all valid address-to-output transitions when both CE and OE are asserted low. The "-12" suffix explicitly denotes this 45 ns speed grade per Atmel's ordering nomenclature.
Does the AT27C256R-12TC require a programming voltage during normal read operation?
No, the AT27C256R-12TC operates at 5V ±10% for all read-mode functions. VPP (12.0 V ±0.5 V) is required exclusively during programming and verification cycles. During standard read operation, VPP must be tied to VCC or left unconnected per datasheet guidance - applying VPP voltage during reads may damage the device or cause undefined behavior.
How does the Rapid™ Programming Algorithm improve efficiency for the AT27C256R-12TC?
The Rapid™ Programming Algorithm reduces AT27C256R-12TC programming time to 100 µs per byte (typical), with built-in verify-and-reprogram loops. It eliminates manual pulse tuning and guarantees successful programming within ≤10 pulses per byte. This cuts total firmware burn time by up to 80% versus legacy EPROM algorithms and enables integration into high-throughput automated programming lines.
Can the AT27C256R-12TC be used in place of a UV-erasable EPROM like the 27C256?
Yes, the AT27C256R-12TC is a functional and pin-compatible replacement for the 27C256 in most 5V systems, offering identical 32K × 8 organization and timing. However, it is one-time programmable (OTP) and lacks UV erasure capability. Its TSOP package also differs physically from the 27C256's PDIP, so mechanical compatibility depends on PCB footprint alignment.
What is the purpose of the Integrated Product Identification Code in the AT27C256R-12TC?
The Integrated Product Identification Code in the AT27C256R-12TC provides two electronically readable bytes: Manufacturer ID (0x1E) and Device Code (0x8C). Accessed by setting A9 to 12.0 V and toggling A0, it enables universal programmers to auto-detect the device type and apply correct programming voltages, pulse widths, and verification sequences - reducing setup errors and improving first-pass yield.
AT27C256R-12TC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 28-TSSOP (0.465", 11.80mm Width)
- Packaging:
- Tray
- 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:
- 120 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSOP
AT27C256R-12TC FAQ
1.How can I place an order for AT27C256R-12TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-12TC 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-12TC reliable?
The price and inventory of AT27C256R-12TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-12TC is usually 5 days.
3.What payment methods are accepted for AT27C256R-12TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-12TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-12TC?
AT27C256R-12TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-12TC 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-12TC?
For technical support, including AT27C256R-12TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-12TC requirements.
6.How does Aetrix verify that AT27C256R-12TC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-12TC 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-12TC meets industry standards.
7.What is the process for return or replacement of AT27C256R-12TC?
All AT27C256R-12TC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-12TC, 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-12TC part is unused and in its original packaging.
Return procedure for AT27C256R-12TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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