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STMicroelectronics M27W256B-80F6
- Part No.:
- M27W256B-80F6
- Manufacturer:
- STMicroelectronics
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm) Window
- Datasheet:
-
M27W256B-80F6.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,132
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Product details
Overview
M27W256B-80F6 from STMicroelectronics is a 256 Kbit (32K × 8) low-voltage UV-erasable EPROM in FDIP28W ceramic frit-seal package with window, supporting 2.7–3.6 V read operation, 80 ns access time at 2.7 V, and TTL-compatible I/O. It serves as nonvolatile program/data storage in legacy microprocessor systems requiring field-erasable reprogramming via UV exposure.
For engineers reviewing the M27W256B-80F6 datasheet, M27W256B-80F6 pinout, M27W256B-80F6 application, or M27W256B-80F6 equivalent, key selection criteria include UV erasability, dual-line output control (E/G), 12.75 V programming voltage, electronic signature (20h/8Dh), and compatibility with Presto II programming algorithm on standard EPROM programmers.
Technical Context
The M27W256B-80F6 implements a two-line output enable architecture: Chip Enable (E) controls power state and device selection, while Output Enable (G) gates data to Q0–Q7 independently-enabling low-power standby (15 µA) and eliminating bus contention in multi-device memory arrays. Its logic diagram confirms full TTL-level input compatibility except for A9 during Electronic Signature mode (11.5–12.5 V).
Programming uses a verified 100 µs/byte pulse algorithm with margin verify at elevated VCC (6.25 V), and erasure requires 2537 Å UV light at ≥15 W·sec/cm² dose (15–20 min at 12,000 µW/cm²). The FDIP28W package features a quartz window for UV transparency and ceramic hermetic sealing for long-term data retention (>10 years).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8 bits); supports byte-wide parallel data access in microprocessor buses. |
| Read Access Time | 80 ns at VCC = 2.7–3.6 V; defines maximum clock rate for reliable instruction fetch in 8-bit systems. |
| Supply Voltage (Read) | 2.7–3.6 V; enables direct interface with 3.3 V logic without level shifters, reducing BOM count. |
| Standby Current | 15 µA max at VCC ≤ 3.6 V; extends battery life in portable embedded controllers and instrumentation. |
| Programming Voltage | VPP = 12.75 V ± 0.25 V; requires dedicated high-voltage supply but ensures reliable cell threshold margin. |
| Electronic Signature | Manufacturer Code = 20h, Device Code = 8Dh; enables automatic algorithm selection in universal EPROM programmers. |
| UV Erase Dose | ≥15 W·sec/cm² at 2537 Å; specifies minimum UV energy required for full bit reset to '1' state. |
Pinout & Package
FDIP28W (28-pin Ceramic Frit-Seal DIP with UV-transparent window), 0.6-inch width, hermetically sealed for >10-year data retention. Pin 1 index corner marked; window centered over die for uniform UV exposure.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus (32K locations); TTL-compatible, driven by MPU address lines. |
| Q0–Q7 | Data Outputs | Bi-directional data bus in programming mode; high-impedance when E or G inactive. |
| E | Chip Enable | Primary device select; VIH places device in standby (15 µA), VIL enables read/program functions. |
| G | Output Enable | Secondary output gate; controls Q0–Q7 drive only-allows E-based power management independent of data flow. |
| VPP | Program Supply | 12.75 V input during programming/verify; must be applied after VCC and removed before VCC. |
| VCC | Supply Voltage | 2.7–3.6 V for read/standby; 6.25 V ± 0.25 V for programming-requires dual-rail support in programmer design. |
| VSS | Ground | Reference for all signals; requires local 0.1 µF ceramic decoupling per device. |
| A9 (ES) | Electronic Signature Input | Accepts 11.5–12.5 V for manufacturer/device ID readout; not used in normal operation. |
Key Features
| Feature | Design Value |
|---|---|
| UV-Erasable Architecture | FDIP28W window enables full chip erase in 15–20 min under 2537 Å UV lamp-supports firmware updates in field-deployed systems. |
| Dual-Line Output Control | Independent E (power) and G (output) pins allow hierarchical memory array design: E selects device, G gates data-eliminating bus contention and minimizing active current. |
| Presto II Programming Algorithm | Guaranteed 100 µs/byte pulses with margin verify at 6.25 V ensure robust programming across temperature and process variation-no over-programming required. |
| Electronic Signature | Factory-programmed 20h/8Dh ID enables plug-and-play recognition in automated programming stations-reducing operator error and setup time. |
| Low-Voltage Read Operation | 2.7–3.6 V supply range allows direct integration into 3.3 V systems without regulators-cutting power loss and thermal load in space-constrained designs. |
Applications
| Industrial PLC Firmware Storage | Legacy Medical Instrument Boot Memory |
|---|---|
|
Use Scenario: Storing fixed boot code and calibration tables in programmable logic controllers deployed in factory automation environments with infrequent firmware updates. IC Role / Device Role / Timing Role: Nonvolatile program memory mapped to CPU address space; accessed during power-on reset sequence with 80 ns timing margin. Use Value: UV erasability allows field reprogramming without board removal; FDIP28W ceramic package withstands industrial temperature cycling (–40°C to +85°C). |
Use Scenario: Holding diagnostic firmware and safety-critical configuration data in electrocardiogram (ECG) machines where regulatory recertification limits update frequency. IC Role / Device Role / Timing Role: Read-only memory for system initialization; operates at 3.3 V with TTL-compatible outputs interfacing directly to 8051-family microcontrollers. Use Value: 15 µA standby current extends battery backup runtime during AC power loss; electronic signature ensures correct algorithm selection in certified programming workflows. |
| Avionics Test Equipment Configuration | Telecom Line Card Boot ROM |
|
Use Scenario: Storing hardware-specific test routines and calibration constants in benchtop avionics testers used across multiple aircraft platforms. IC Role / Device Role / Timing Role: Byte-addressable EPROM providing deterministic 80 ns read latency for real-time test pattern generation. Use Value: Dual-line control (E/G) enables selective activation of multiple EPROMs on shared data bus-reducing signal integrity issues in high-density tester backplanes. |
Use Scenario: Hosting boot loader and FPGA configuration bitstream in telecom line cards requiring field-upgradable firmware with traceable revision control. IC Role / Device Role / Timing Role: Primary boot memory mapped to processor reset vector; programmed once per production batch using Presto II algorithm. Use Value: ECOPACK®-compliant lead-free FDIP28W package meets RoHS requirements for telecom infrastructure; UV window allows post-deployment verification of bitstream integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar UV-erasable EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-80DC | 5 V-only operation (no 2.7–3.6 V read mode); 80 ns access at 5 V; same 28-pin PDIP package but no UV window. | Requires 5 V supply rail; unsuitable for battery-powered or mixed-voltage systems; OTP-only-no field erasure capability. | Select only if legacy 5 V infrastructure exists and UV erasure is unnecessary; verify compatibility with existing programmer voltage rails. |
| M27C256B-10F1 | Same 2.7–5.5 V read range and FDIP28W package; 100 ns access time; identical electronic signature (20h/8Dh) and Presto II support. | Slower timing margin (100 ns vs. 80 ns) limits use in high-speed 8 MHz+ Z80/8085 systems; otherwise functionally interchangeable. | Prefer for cost-sensitive designs where 20 ns timing slack is acceptable; validated drop-in replacement in ST's reference designs. |
Compared with AM27C256B-80DC, M27W256B-80F6 enables lower-power 3.3 V operation and field erasure; versus M27C256B-10F1, it delivers tighter 80 ns timing for faster microprocessor interfaces-making it optimal for space-constrained, battery-aware, and upgradeable embedded systems.
Availability
M27W256B-80F6 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy medical instrument boot memory, avionics test equipment configuration, and telecom line card boot ROM requiring stable component supply amid obsolescence challenges.
Supply support for M27W256B-80F6 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with strong heritage in nonvolatile memory design.
The M27W256 belongs to ST's legacy EPROM product line, engineered specifically for reliability-critical embedded systems requiring field-erasable, long-retention, and programmer-agnostic nonvolatile storage-prioritizing manufacturability, UV endurance, and backward compatibility.
FAQ
Is M27W256B-80F6 still in production?
No-M27W256B-80F6 is officially obsolete per STMicroelectronics' product change notification (PCN), last manufactured in 2006. However, Aetrix Electronics maintains verified, traceable inventory from original ST packaging with full lot traceability and extended shelf-life validation for legacy system sustainment.
What UV wavelength and exposure time are required for full erasure?
Full erasure requires short-wave ultraviolet light at 2537 Å with a minimum integrated dose of 15 W·sec/cm². Using a standard 12,000 µW/cm² UV lamp, place the FDIP28W window 2.5 cm from the source for 15–20 minutes. Avoid fluorescent ambient light exposure, which may cause partial erasure over months.
Can M27W256B-80F6 be programmed on a standard M27C256B programmer?
Yes-M27W256B-80F6 shares identical pinout, electronic signature (20h/8Dh), and Presto II programming algorithm with M27C256B. It requires the same 12.75 V VPP and 6.25 V VCC during programming, and supports the same 100 µs/byte pulse sequence and margin verify protocol.
Does the FDIP28W package support reflow soldering?
No-FDIP28W is a ceramic frit-seal package with glass-to-metal seals and UV-transparent window; it is rated for wave soldering only. Reflow exceeds its thermal limit (peak 215°C max) and risks seal fracture or window delamination. Hand soldering or wave soldering with preheat ≤150°C is required.
M27W256B-80F6 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 28-CDIP (0.600", 15.24mm) Window
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- EPROM
- Technology:
- EPROM - UV
- Memory Size:
- 256Kbit
- Memory Organization:
- 32K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- -
- Access Time:
- 80 ns
- Voltage - Supply:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CDIP Frit Seal with Window
M27W256B-80F6 FAQ
1.How can I place an order for M27W256B-80F6 through Aetrix?
Please submit a Request for Quotation (RFQ) for M27W256B-80F6 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 M27W256B-80F6 reliable?
The price and inventory of M27W256B-80F6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27W256B-80F6 is usually 5 days.
3.What payment methods are accepted for M27W256B-80F6?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27W256B-80F6 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M27W256B-80F6?
M27W256B-80F6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M27W256B-80F6 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 M27W256B-80F6?
For technical support, including M27W256B-80F6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27W256B-80F6 requirements.
6.How does Aetrix verify that M27W256B-80F6 is sourced from the original manufacturer or authorized distributors?
All M27W256B-80F6 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 M27W256B-80F6 meets industry standards.
7.What is the process for return or replacement of M27W256B-80F6?
All M27W256B-80F6 units undergo pre-shipment inspection (PSI). If there is an issue with M27W256B-80F6, 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 M27W256B-80F6 part is unused and in its original packaging.
Return procedure for M27W256B-80F6:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M27W256B-80F6 Tags
-
M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
Microchip Technology
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Microchip Technology
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24LC01BT-I/OT
Microchip Technology
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M24C02-FMC6TG
STMicroelectronics
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AT24CS02-SSHM-T
Microchip Technology
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93LC46BT-I/OT
Microchip Technology
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AT24C04C-SSHM-T
Microchip Technology
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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