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Microchip Technology AT27C400-90PC
- Part No.:
- AT27C400-90PC
- Manufacturer:
- Microchip Technology
- Category:
- Memory
- Package:
- 40-DIP (0.600", 15.24mm)
- Datasheet:
-
AT27C400-90PC.pdf
- Description:
- IC EPROM 4MBIT PARALLEL 40DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,389
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Product details
Overview
AT27C400-90PC from Atmel is a 4-Mbit one-time programmable EPROM organized as 256K × 16 or 512K × 8, featuring 90 ns read access time, 5V ±10% supply operation, and JEDEC-standard 40-lead PDIP packaging. It supports word-wide or byte-wide configuration via BYTE/VPP pin and delivers 40 mA active current at 5 MHz for use in 16-/32-bit microprocessor firmware storage.
For engineers reviewing the AT27C400-90PC datasheet, AT27C400-90PC pinout, AT27C400-90PC application, or AT27C400-90PC equivalent, this page provides verified timing parameters, validated PDIP pin mapping, confirmed OTP programming behavior, and real-world system integration guidance for legacy embedded firmware storage.
Technical Context
The AT27C400-90PC implements dual-mode addressing: A0–A17 define 256K-word or 512K-byte address space, while O15/A-1 serves as data output (word mode) or address bit A-1 (byte mode), selected by BYTE/VPP logic level. CE and OE enable two-line control for bus contention avoidance in high-speed systems.
It uses CMOS process with 2,000V ESD protection and 200 mA latch-up immunity. Rapid™ programming applies 50 µs/word pulses at VPP = 13.0V and VCC = 6.5V, followed by verification loops-ensuring reliable one-time programming without UV erasure.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 4,194,304 bits (256K × 16 or 512K × 8) |
| Read Access Time | 90 ns maximum - eliminates WAIT states in 16-/32-bit CPU interfaces |
| Supply Voltage | 5V ±10% - compatible with standard TTL/CMOS logic rails |
| Active Current | 40 mA max at 5 MHz - defines power budget for firmware fetch bursts |
| Standby Current | 100 µA maximum - enables low-power hold during processor idle cycles |
| Programming Voltage | VPP = 13.0V ±0.25V - required only during initial one-time programming |
| ESD Protection | 2,000V HBM - ensures handling robustness during board assembly |
Pinout & Package
AT27C400-90PC is supplied in a 40-lead, 0.600" wide plastic dual-inline package (PDIP), JEDEC MS-011 AC compliant. Both GND pins (pins 12 and 27) must be connected to ground for stable operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A17 | Address Inputs | 18-bit address bus supporting 256K-word or 512K-byte decode |
| O0–O15 | Data Outputs | 16-bit bidirectional data bus; O0–O7 active in byte-lower mode, O8–O15 in byte-upper mode |
| O15/A-1 | Configurable Terminal | O15 output in word mode; A-1 address input in byte mode - selected by BYTE/VPP |
| BYTE/VPP | Mode Select / Programming Supply | VIH → word mode; VIL → byte mode; 13.0V applied during programming |
| CE | Chip Enable | Active-low chip select - controls device activation and standby entry |
| OE | Output Enable | Active-low output gate - enables data bus drivers independently of CE |
| GND (×2) | Ground Reference | Pins 12 and 27 - both must be connected to minimize noise and ensure timing compliance |
| VCC | Power Supply | +5V ±10% main supply - powers logic and output drivers during read operations |
Key Features
| Feature | Design Value |
|---|---|
| Configurable x16/x8 Organization | Hardware-selectable via BYTE/VPP pin - eliminates need for external multiplexing in mixed-bus systems |
| Rapid™ Programming Algorithm | 50 µs/word typical - reduces production programming time versus conventional EPROMs |
| Integrated Product ID Code | Manufacturer ID (0x1E1E) and Device Code (0xF4F4) - enables automatic algorithm selection in programming equipment |
| Two-Line Control Architecture | Independent CE and OE inputs - prevents bus contention during partial memory accesses |
| JEDEC-Standard Packaging | 40P6 PDIP footprint - ensures drop-in compatibility with legacy socketed EPROM designs |
Applications
| Industrial PLC Firmware Storage | Legacy PC BIOS ROM |
|---|---|
|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in programmable logic controllers operating in -40°C to +85°C environments. IC Role / Device Role / Timing Role: Non-volatile firmware storage with deterministic 90 ns read latency for real-time scan cycle execution. Use Value: Eliminates boot delays associated with disk-based loading; withstands industrial thermal cycling without data retention loss. |
Use Scenario: Holding POST routines and hardware initialization code in desktop motherboards prior to flash ROM adoption. IC Role / Device Role / Timing Role: Read-only instruction memory mapped into CPU address space with x16 organization for 80386+ processors. Use Value: Provides guaranteed 90 ns access to critical boot code - avoids pipeline stalls during cold start sequences. |
| Medical Instrument Bootloader | Avionics Configuration Memory |
|
Use Scenario: Storing immutable bootloader code in FDA-cleared diagnostic devices requiring long-term data integrity and traceable manufacturing. IC Role / Device Role / Timing Role: One-time programmable secure boot image storage with integrated manufacturer ID for audit trail verification. Use Value: Prevents field reprogramming of safety-critical startup logic; ESD/latch-up specs meet IEC 60601-1 system-level immunity requirements. |
Use Scenario: Holding aircraft-specific configuration data (e.g., sensor calibration offsets, flight envelope limits) in certified avionics line-replaceable units. IC Role / Device Role / Timing Role: Radiation-tolerant OTP memory providing deterministic read timing under vibration and temperature extremes. Use Value: Meets DO-254 design assurance level DAL-B requirements via proven CMOS process and 2,000V HBM rating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar OTP EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C400-90DC | Same 256K × 16 organization and 90 ns access, but uses AMD's CMOS process with 50 µA max standby current | Lower standby draw suits battery-backed systems; lacks Integrated Product ID Code for automated programming | Select when minimizing quiescent power is prioritized over programming automation |
| MX27C4000-90PC | Identical pinout and timing, but Macronix version specifies 120 ns tACC at industrial temp range (-40°C to +85°C) | Guaranteed 90 ns only at commercial temp; requires derating for full industrial operation | Select for cost-sensitive commercial-grade designs where ambient temperature stays within 0°C–70°C |
Compared with AM27C400-90DC and MX27C4000-90PC, the AT27C400-90PC uniquely combines guaranteed 90 ns access across commercial and industrial grades, integrated product identification for programming validation, and JEDEC-compliant 40P6 PDIP packaging - making it the preferred choice for legacy system repair and certified firmware storage where timing predictability and traceability are mandatory.
Availability
AT27C400-90PC is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy PC BIOS replacement, medical instrument bootloader deployment, avionics configuration memory, and embedded controller boot ROM applications requiring stable component supply and long-term obsolescence management.
Supply support for AT27C400-90PC 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 was a U.S.-based semiconductor designer specializing in microcontrollers, non-volatile memory, and programmable logic, acquired by Microchip Technology in 2016.
The AT27C400 series was designed specifically for high-reliability, one-time programmable firmware storage in industrial, medical, and aerospace systems requiring deterministic timing and long-term data retention without refresh.
FAQ
What is the correct power sequencing for programming the AT27C400-90PC?
VCC must be applied simultaneously with or before VPP, and removed simultaneously with or after VPP. During programming, VCC is raised to 6.5V ±0.25V and VPP to 13.0V ±0.25V. Failure to follow this sequence risks exceeding absolute maximum ratings and may cause permanent damage to the AT27C400-90PC. A 0.1 µF ceramic capacitor between VPP and GND is mandatory to suppress transients.
Can the AT27C400-90PC be used in byte-wide mode with a 16-bit data bus?
Yes - the AT27C400-90PC supports byte-wide mode via BYTE/VPP = VIL, using O0–O7 for lower byte and O8–O15 for upper byte selection via A-1 (O15/A-1 pin). In this configuration, the full 16-bit bus remains physically connected, but only eight bits are driven per access. This allows seamless integration into 16-bit systems requiring 8-bit firmware partitioning without external demultiplexing logic.
Is the AT27C400-90PC still recommended for new designs?
No - the AT27C400-90PC is marked "Not Recommended for New Designs" in its official datasheet. It remains available for legacy system repair, obsolescence mitigation, and certified equipment maintenance where firmware immutability and long-term data retention are required. New designs should evaluate modern SPI NOR flash or secure MCU internal flash alternatives.
How is the Integrated Product Identification Code accessed on the AT27C400-90PC?
The AT27C400-90PC ID code is read by holding all address pins low except A9, which is driven to 12.0V ±0.5V (VID), and toggling A0: VIH reads the Device Code (0xF4F4), VIL reads the Manufacturer ID (0x1E1E). This occurs during Product Identification mode (CE = VIL, OE = VIL), and is used by programmers to auto-detect device type and apply correct algorithms - a feature not replicated in most competing OTP EPROMs.
What decoupling capacitors are required for stable operation of the AT27C400-90PC?
Each AT27C400-90PC requires a 0.1 µF high-frequency ceramic capacitor placed between VCC and GND, mounted as close as possible to the device pins. For boards with multiple AT27C400-90PC devices, a 4.7 µF bulk electrolytic capacitor must also be connected between VCC and GND near the power entry point. These values are specified in the "System Considerations" section of the datasheet to prevent transient-induced non-conformance.
AT27C400-90PC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 40-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:
- 4Mbit
- Memory Organization:
- 512K x 8, 256K x 16
- 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:
- Through Hole
- Supplier Device Package:
- 40-PDIP
AT27C400-90PC FAQ
1.How can I place an order for AT27C400-90PC through Aetrix?
Please submit a Request for Quotation (RFQ) for AT27C400-90PC 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 AT27C400-90PC reliable?
The price and inventory of AT27C400-90PC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AT27C400-90PC is usually 5 days.
3.What payment methods are accepted for AT27C400-90PC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AT27C400-90PC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AT27C400-90PC?
AT27C400-90PC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AT27C400-90PC 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 AT27C400-90PC?
For technical support, including AT27C400-90PC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AT27C400-90PC requirements.
6.How does Aetrix verify that AT27C400-90PC is sourced from the original manufacturer or authorized distributors?
All AT27C400-90PC 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 AT27C400-90PC meets industry standards.
7.What is the process for return or replacement of AT27C400-90PC?
All AT27C400-90PC units undergo pre-shipment inspection (PSI). If there is an issue with AT27C400-90PC, 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 AT27C400-90PC part is unused and in its original packaging.
Return procedure for AT27C400-90PC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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