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Microchip Technology AT27C256R-70JU-306
- Part No.:
- AT27C256R-70JU-306
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 32-LCC (J-Lead)
- Datasheet:
-
AT27C256R-70JU-306.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 32PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:1,040
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Product details
Overview
AT27C256R-70JU-306 from Microchip Technology (formerly Atmel) is a 32K × 8-bit, one-time programmable EPROM used for firmware storage in microprocessor systems. It delivers 45ns read access time, operates on a single 5V ±10% supply, and supports industrial temperature range (–40°C to +85°C) in a 32-lead PLCC package with matte tin lead finish.
For engineers reviewing the AT27C256R-70JU-306 datasheet, AT27C256R-70JU-306 pinout, AT27C256R-70JU-306 application, or AT27C256R-70JU-306 equivalent, this device serves as a low-power, high-reliability OTP memory solution for boot code, configuration data, and fixed algorithm storage where non-volatility and immunity to accidental rewrites are critical.
Technical Context
The AT27C256R-70JU-306 implements a CMOS-based OTP EPROM architecture with dual-line control (CE/OE) enabling bus contention prevention in shared-memory systems. Its rapid programming algorithm uses 100µs/byte CE pulses at VPP = 13.0V and VCC = 6.5V, followed by verification loops per address.
It features integrated product identification (manufacturer code 0x1E, device code 0x8C), 2,000V HBM ESD protection, and 200mA latchup immunity. The device requires decoupling: 0.1µF ceramic capacitor near VCC/GND plus 4.7µF bulk electrolytic for arrays - both specified in system design guidance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory size | 262,144 bits (32K × 8), sufficient for full boot ROM or FPGA configuration bitstreams |
| Read access time | 70 ns max (–70 speed grade), eliminates WAIT states in 14 MHz Z80 or 8086-class systems |
| VCC supply | 5 V ±10%, compatible with legacy TTL/CMOS logic rails without level translation |
| Standby current | 100 µA max, enables low-power hold mode during processor sleep cycles |
| Active current | 20 mA max at 5 MHz, supports burst reads without thermal derating in compact PCB layouts |
| Programming voltage | VPP = 12.0 V ±0.5 V, requires dedicated high-voltage programming circuitry or commercial EPROM programmer |
| Operating temperature | –40°C to +85°C, qualified for industrial control panels and factory automation hardware |
Pinout & Package
AT27C256R-70JU-306 is housed in a 32-lead plastic J-leaded chip carrier (PLCC), JEDEC MS-016 compliant, with 11.5 mm × 14.0 mm body and 1.27 mm pitch. Pin 1 identifier located at top-left corner; pins 1 and 17 are no-connect (NC).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address inputs | 15-bit address bus interface supporting full 32K address space; TTL/CMOS-compatible thresholds |
| O0–O7 | Data outputs | 8-bit bidirectional data bus outputs with VOH ≥ 2.4 V @ –400 µA, VOL ≤ 0.4 V @ 2.1 mA |
| CE | Chip enable | Active-low primary selection signal; controls power state transition between active/standby |
| OE | Output enable | Active-low secondary control; enables output drivers only when CE is also asserted |
| VCC | Power supply | +5 V ±10% main supply; must be applied simultaneously with or before VPP during programming |
| VPP | Programming voltage | +12.0 V ±0.5 V input for byte programming; requires external 0.1 µF decoupling to ground |
| GND | Ground reference | Signal and power return path; decoupling capacitor must connect here and to VCC |
| NC | No connect | Pins 1 and 17 are internally unconnected; must remain floating per datasheet |
Key Features
| Feature | Design Value |
|---|---|
| Rapid programming | 100 µs/byte typical programming time reduces firmware update cycle duration in production programming stations |
| Integrated ID code | Manufacturer (0x1E) and device (0x8C) codes enable automatic algorithm selection in industry-standard programmers |
| Two-line control | Independent CE and OE inputs allow flexible bus arbitration and eliminate contention during multi-device memory mapping |
| High-reliability process | 2,000 V HBM ESD rating and 200 mA latchup immunity ensure robustness in manual handling and noisy industrial environments |
| Green packaging | Pb/halide-free PLCC construction complies with RoHS Directive 2011/65/EU without requiring process requalification |
Applications
| Industrial PLC Firmware Storage | Legacy Embedded Boot ROM |
|---|---|
|
Use Scenario: Storing fixed ladder logic interpreter and I/O initialization routines in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic startup sequence with zero rewrite risk after field deployment. Use Value: Eliminates need for battery-backed SRAM or EEPROM wear leveling; 45ns access ensures real-time scan cycle timing integrity. |
Use Scenario: Holding BIOS-equivalent startup code for 8-bit microcontrollers (e.g., Z80, 8051) in medical diagnostic instruments. IC Role / Device Role / Timing Role: Primary read-only instruction store mapped to reset vector address space. Use Value: Immunity to electromagnetic interference prevents corruption during power-up transients in hospital-grade equipment. |
| Automotive ECU Calibration Data | Test Equipment Configuration Memory |
|
Use Scenario: Storing engine calibration maps and sensor offset tables in Tier-1 automotive ECUs operating within extended temperature range. IC Role / Device Role / Timing Role: Read-only parameter repository accessed during cold-start fuel enrichment calculations. Use Value: Industrial-grade temp range (–40°C to +85°C) and 200 mA latchup immunity meet AEC-Q100 stress requirements for under-hood use. |
Use Scenario: Retaining instrument-specific calibration coefficients and test sequence definitions in automated benchtop testers. IC Role / Device Role / Timing Role: Static configuration database accessed once per test session during initialization. Use Value: One-time programmability prevents accidental overwrites during technician reprogramming, ensuring traceable metrology compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AT27C256R-70PU | Same die, 28-lead PDIP package instead of 32-lead PLCC; no pin 17 NC, different footprint and thermal profile | Suitable for through-hole prototyping or legacy wave-soldered assemblies; lacks PLCC's surface-mount density and mechanical stability | Select when board layout uses 0.600" DIP sockets or requires manual rework accessibility |
| MX27C256 (Macronix) | Functionally identical 32K×8 OTP EPROM but with 100 ns max tACC; no integrated ID code; VPP tolerance ±1.0 V vs. ±0.5 V | Acceptable for cost-sensitive industrial designs where programming verification is handled externally and tighter VPP regulation is unavailable | Select only if system-level programming infrastructure does not rely on automatic ID-based algorithm selection |
Compared with AT27C256R-70JU-306, the AT27C256R-70PU offers identical electrical behavior in a through-hole package ideal for development, while MX27C256 trades integrated identification and tighter VPP tolerance for broader second-source availability - neither is pin-compatible due to differing lead counts and PLCC vs. PDIP form factors.
Availability
AT27C256R-70JU-306 is available at Aetrix Electronics and suitable for industrial control systems, legacy embedded instrumentation, and automotive calibration modules requiring stable component supply across long product lifecycles.
Supply support for AT27C256R-70JU-306 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 technical and manufacturing continuity for legacy Atmel memory products including the AT27C series.
The AT27C256R belongs to Atmel's OTP EPROM product line, designed specifically for applications demanding permanent, tamper-resistant firmware storage without battery backup or write endurance concerns.
FAQ
What is the maximum operating temperature range for the AT27C256R-70JU-306?
The AT27C256R-70JU-306 is rated for industrial operation from –40°C to +85°C. This range is validated per the datasheet's "Operating temp. (case)" specification for the –70 speed grade and applies to both read and standby modes. It does not support automotive (–40°C to +125°C) or extended military ranges.
Can the AT27C256R-70JU-306 be reprogrammed after initial programming?
No, the AT27C256R-70JU-306 is a one-time programmable (OTP) EPROM. Once programmed, its contents cannot be erased or rewritten electrically or via UV exposure. The silicon structure lacks an erasure window and uses fusible-link or floating-gate technology that permanently alters conduction paths during programming.
What decoupling capacitors are required for stable operation of the AT27C256R-70JU-306?
The AT27C256R-70JU-306 requires two decoupling capacitors: a 0.1 µF high-frequency ceramic capacitor placed directly between VCC and GND as close to the device as possible, and a 4.7 µF bulk electrolytic capacitor located near the power entry point for arrays. These values are specified in the "System considerations" section to suppress transient excursions during CE switching.
Does the AT27C256R-70JU-306 support standard microprocessor bus timing?
Yes, the AT27C256R-70JU-306 supports standard microprocessor bus timing with tACC = 70 ns max, tCE = 70 ns max, and tOE = 30 ns max. Its CE/OE dual-control architecture aligns with Intel 8086/8088 and Motorola 68000 timing models, and its TTL/CMOS-compatible inputs eliminate need for bus transceivers in mixed-logic systems.
How is the product identification code accessed on the AT27C256R-70JU-306?
The AT27C256R-70JU-306 product identification code is accessed by setting A9 to VH = 12.0 V ±0.5 V while holding A1–A14 low, then toggling A0: low selects the manufacturer ID byte (0x1E), high selects the device ID byte (0x8C). This mode is documented in Table 5-1 under "Product identification" and requires VPP = VCC during read.
AT27C256R-70JU-306 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 32-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Active
- 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:
- -40°C ~ 85°C (TC)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-PLCC (13.97x11.43)
AT27C256R-70JU-306 FAQ
1.How can I place an order for AT27C256R-70JU-306 through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C256R-70JU-306 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-70JU-306 reliable?
The price and inventory of AT27C256R-70JU-306 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C256R-70JU-306 is usually 5 days.
3.What payment methods are accepted for AT27C256R-70JU-306?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C256R-70JU-306 transactions.
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4.How is shipping managed for AT27C256R-70JU-306?
AT27C256R-70JU-306 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C256R-70JU-306 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-70JU-306?
For technical support, including AT27C256R-70JU-306 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C256R-70JU-306 requirements.
6.How does Aetrix verify that AT27C256R-70JU-306 is sourced from the original manufacturer or authorized distributors?
All AT27C256R-70JU-306 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-70JU-306 meets industry standards.
7.What is the process for return or replacement of AT27C256R-70JU-306?
All AT27C256R-70JU-306 units undergo pre-shipment inspection (PSI). If there is an issue with AT27C256R-70JU-306, 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-70JU-306 part is unused and in its original packaging.
Return procedure for AT27C256R-70JU-306:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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