My Inquiry
My Account
Microchip Technology AT27C256R-55TC
- Part No.:
- AT27C256R-55TC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 28-TSSOP (0.465", 11.80mm Width)
- Datasheet:
-
AT27C256R-55TC.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28TSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,621
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
AT27C256R-55TC from Microchip Technology (formerly Atmel) is a 32K × 8-bit one-time programmable EPROM with 55 ns maximum read access time, 5V ±10% supply operation, and JEDEC-standard 28-lead TSOP 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-55TC datasheet, AT27C256R-55TC pinout, AT27C256R-55TC application, or AT27C256R-55TC equivalent, key selection criteria include verified 55 ns tACC, industrial temperature range support (–40°C to +85°C), TSOP-28 mechanical compatibility, and Rapid™ programming at 100 µs/byte.
Technical Context
The AT27C256R-55TC implements a CMOS OTP EPROM architecture with dual-line control (CE/OE) enabling bus contention avoidance in shared-memory systems. Its address space spans A0–A14 (15-bit), supporting 32,768 bytes of directly accessible storage without external decoding logic.
It features integrated product identification (manufacturer code 0x1E, device code 0x8C) readable via A9 high-voltage mode (12.0 V ±0.5 V), and supports rapid programming with 13.0 V VPP and 6.5 V VCC during write cycles-distinct from its 5V-only read operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 32K × 8-bit (262,144 bits), sufficient for full boot ROM or firmware image in 8-bit/16-bit microcontrollers |
| Read Access Time (tACC) | 55 ns max - guarantees sub-18 MHz CPU interface without wait-state insertion |
| Supply Voltage | 5V ±10% - compatible with legacy TTL/CMOS logic rails and eliminates need for auxiliary voltage regulators |
| Standby Current | 100 µA max - enables low-power retention in battery-backed or energy-constrained embedded systems |
| Operating Temperature | –40°C to +85°C - validated for industrial-grade reliability in factory automation and motor control environments |
| Programming Voltage (VPP) | 13.0 V ±0.25 V - requires dedicated programming hardware; not used during normal read operation |
| ESD Protection | 2,000 V HBM - meets IEC 61000-4-2 Level 2 for handling robustness in manufacturing and field service |
Pinout & Package
AT27C256R-55TC is housed in a 28-lead Thin Small Outline Package (TSOP, Type 1, JEDEC MO-153), 11.7 mm × 7.9 mm footprint, 1.05 mm max height, gull-wing leads, lead pitch 0.55 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus accepting 0–32767; fully decoded internally to select byte location |
| O0–O7 | Data Outputs | 8-bit bidirectional data bus in read mode; high-impedance when CE or OE inactive |
| CE | Chip Enable | Active-low chip select; must be asserted before OE to enable output drivers and prevent bus contention |
| OE | Output Enable | Active-low output gate; allows multiple devices on same data bus with staggered OE timing |
| VPP | Programming Voltage | 13 V input only during programming; must be ramped with VCC and isolated from 5V system rail during read |
| VCC | Power Supply | 5V ±10% main supply; powers logic and outputs; requires local 0.1 µF ceramic decoupling |
| GND | Ground Reference | Signal and power return; must be low-inductance connection adjacent to VCC decoupling cap |
| NC | No Connect | Pins 1, 21, and 22 are unconnected in TSOP package; must remain floating, not tied to any net |
Key Features
| Feature | Design Value |
|---|---|
| Rapid™ Programming Algorithm | 100 µs/byte typical programming time reduces production burn-in cycle duration by >5× vs. legacy EPROMs |
| Integrated Product ID Code | Manufacturer (0x1E) and device (0x8C) codes enable automated programmer validation and BOM traceability |
| Two-Line Control Architecture | Independent CE and OE pins allow flexible memory mapping and multi-device arbitration without external logic |
| High-Reliability CMOS Process | 200 mA latchup immunity and 2 kV ESD rating ensure robustness in noisy industrial PCB environments |
| JEDEC-Standard Packaging | TSOP-28 footprint matches industry layout standards, enabling drop-in replacement across vendor families |
Applications
| Industrial PLC Firmware Storage | Legacy Embedded Boot ROM |
|---|---|
Use Scenario: Storing ladder logic interpreter and I/O configuration in programmable logic controllers operating in factory-floor environments with wide temperature swings and electrical noise. IC Role / Device Role / Timing Role: Nonvolatile boot memory providing deterministic 55 ns read latency to initialize CPU and peripherals before real-time control loop starts. Use Value: Eliminates reliance on slow serial EEPROM or external flash, reducing boot time to <10 ms and ensuring repeatable startup behavior across thermal cycles. | Use Scenario: Holding BIOS-equivalent initialization code for 8051- or Z80-based medical instrumentation where firmware integrity and long-term data retention are critical. IC Role / Device Role / Timing Role: OTP EPROM acting as immutable firmware vault; immune to accidental overwrite during field updates or power faults. Use Value: Guarantees firmware authenticity over 20+ years with zero bit errors, meeting IEC 62304 Class C software safety requirements. |
| Automotive ECU Calibration Data | Test Equipment Configuration Memory |
Use Scenario: Storing engine calibration maps and sensor compensation tables in automotive body control modules certified for –40°C to +85°C operation. IC Role / Device Role / Timing Role: Read-only storage accessed during ECU power-up and runtime lookup; no write cycles after initial programming. Use Value: Provides guaranteed data retention under thermal cycling and vibration stress, avoiding SRAM volatility or flash wear-out concerns. | Use Scenario: Holding instrument-specific setup parameters (e.g., sampling rate, trigger thresholds, channel scaling) in benchtop oscilloscopes and logic analyzers. IC Role / Device Role / Timing Role: Factory-programmed configuration store loaded at power-on to configure FPGA or ASIC peripherals. Use Value: Enables zero-touch calibration and eliminates manual setup steps, improving test throughput and repeatability across production units. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256B-55TC | Successor revision with identical pinout, timing, and programming specs; improved process yield and tighter ICC tolerance (20 mA active vs. 20 mA nominal) | No functional change; suitable for new designs but not required for legacy board refresh | Select AT27C256B-55TC for new designs requiring latest qualification; AT27C256R-55TC remains valid for existing production. |
| MX27C256-55PC | Same 32K×8 OTP EPROM function, 55 ns speed grade, but in 28-lead PDIP (not TSOP); higher standby current (200 µA vs. 100 µA) | Requires PCB footprint change; suited for prototyping or through-hole assembly, not surface-mount volume production | Choose MX27C256-55PC only if PDIP packaging is mandated; otherwise prefer TSOP-compatible alternatives. |
Compared with AT27C256R-55TC, the AT27C256B-55TC offers identical functionality with enhanced manufacturing consistency, while MX27C256-55PC trades surface-mount compatibility for through-hole ease-of-use-neither provides pin-to-pin equivalence in TSOP form factor.
Availability
AT27C256R-55TC is available at Aetrix Electronics and suitable for industrial control systems, legacy embedded boot applications, and automotive calibration storage requiring stable component supply, long-lifecycle support, and verified 55 ns timing compliance.
Supply support for AT27C256R-55TC 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 reliable, low-cost, nonvolatile firmware storage in cost-sensitive industrial and automotive applications where reprogrammability is unnecessary.
FAQ
What is the maximum read access time specified for the AT27C256R-55TC?
The AT27C256R-55TC has a maximum read access time (tACC) of 55 ns under industrial temperature conditions (–40°C to +85°C) and 5V ±10% supply. This value is guaranteed across all operating corners and is measured from address valid to valid data output with CE and OE both asserted low. The "-55" suffix explicitly denotes this speed grade.
Does the AT27C256R-55TC require a programming voltage during normal operation?
No, the AT27C256R-55TC operates solely from a 5V ±10% supply during read mode. VPP (13.0 V ±0.25 V) is required only during factory programming or reprogramming-never during system runtime. In active or standby read modes, VPP must be tied to VCC or left floating per datasheet guidance; applying 13 V during read will damage the device.
Can the AT27C256R-55TC be used as a direct replacement for the AT27C256R-45TC?
No, the AT27C256R-55TC is not a direct replacement for the AT27C256R-45TC in timing-critical systems. While pinout and function are identical, the 55 ns access time is 10 ns slower than the 45 ns spec of the -45TC variant. Systems designed for 45 ns timing margins may experience read failures or require clock throttling when substituting the -55TC.
What package type does the AT27C256R-55TC use, and is it RoHS compliant?
The AT27C256R-55TC uses a 28-lead Thin Small Outline Package (TSOP, Type 1, JEDEC MO-153). Per Microchip's product change notifications, this part is available in both standard (lead-based) and RoHS-compliant (lead-free) versions; the RoHS-compliant variant carries the suffix "-55TCT" and requires reflow profile adjustments due to higher melting point solder.
How is the Integrated Product Identification Code accessed on the AT27C256R-55TC?
The Integrated Product Identification Code on the AT27C256R-55TC is accessed by setting A9 to 12.0 V ±0.5 V (VID), holding A1–A14 low, and toggling A0 between low and high to read the manufacturer ID byte (0x1E) and device code byte (0x8C) on O7–O0. This mode requires a dedicated high-voltage signal and is used exclusively by programming equipment-not during normal system operation.
AT27C256R-55TC 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:
- 55 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-55TC FAQ
1.How can I place an order for AT27C256R-55TC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-55TC 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-55TC reliable?
The price and inventory of AT27C256R-55TC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-55TC is usually 5 days.
3.What payment methods are accepted for AT27C256R-55TC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-55TC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C256R-55TC?
AT27C256R-55TC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-55TC 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-55TC?
For technical support, including AT27C256R-55TC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-55TC requirements.
6.How does Aetrix verify that AT27C256R-55TC is sourced from the original manufacturer or authorized distributors?
All AT27C256R-55TC 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-55TC meets industry standards.
7.What is the process for return or replacement of AT27C256R-55TC?
All AT27C256R-55TC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-55TC, 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-55TC part is unused and in its original packaging.
Return procedure for AT27C256R-55TC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
AT27C256R-55TC Tags
-
M24C02-WMN6TP
STMicroelectronics
-
AT24C02C-XHM-T
Microchip Technology
-
AT21CS01-STUM10-T
Microchip Technology
-
AT24C02C-SSHM-T
Microchip Technology
-
24LC01BT-I/OT
Microchip Technology
-
M24C02-FMC6TG
STMicroelectronics
-
AT24CS02-SSHM-T
Microchip Technology
-
93LC46BT-I/OT
Microchip Technology
-
AT24C04C-SSHM-T
Microchip Technology
-
24LC01BT-I/SN
Microchip Technology
-
24AA02UIDT-I/OT
Microchip Technology
-
AT24C08C-STUM-T
Microchip Technology
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
