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STMicroelectronics M27C256B-10F1
- Part No.:
- M27C256B-10F1
- Manufacturer:
- STMicroelectronics
- Category:
- Memory
- Package:
- 28-CDIP (0.600", 15.24mm) Window
- Datasheet:
-
M27C256B-10F1.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28CDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,293
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Product details
Overview
M27C256B-10F1 from STMicroelectronics is a 256 Kbit (32K × 8) UV-erasable EPROM in FDIP28W ceramic window package, operating at 5V ±10%, with 100 ns access time, 30 mA active current, and 100 µA standby current. It supports electronic signature verification (Manufacturer Code 20h, Device Code 8Dh) and is used in legacy microprocessor boot memory, industrial controller firmware storage, and embedded system configuration retention.
For engineers reviewing the M27C256B-10F1 datasheet, M27C256B-10F1 pinout, M27C256B-10F1 application, or M27C256B-10F1 equivalent, this page delivers verified functional identity, package-specific terminal mapping, timing-critical AC/DC specifications, UV erasure requirements, and two validated drop-in alternatives for legacy system maintenance and redesign.
Technical Context
The M27C256B-10F1 implements a TTL-compatible, two-line output control architecture using Chip Enable (E) for power gating and Output Enable (G) for bus contention prevention-enabling low-power array operation with guaranteed high-impedance outputs during deselect. Its programming mode requires VPP = 12.75V ±0.25V, VCC = 6.25V ±0.25V, and 100 µs pulse width per byte.
Electronic signature mode activates via 11.5–12.5 V on A9 with VCC = VPP = 5 V, allowing automated device identification by programmers; UV erasure requires ≥15 W·s/cm² dose at 2537 Å wavelength, typically achieved in 15–20 minutes at ≤2.5 cm distance from unfiltered UV lamp.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8), fixed parallel organization for direct CPU address/data bus interfacing |
| Access Time | 100 ns (tAVQV), defines maximum clock rate for reliable read cycles in 8-bit microprocessor systems |
| Supply Voltage | 5 V ±10% in read mode; enables compatibility with legacy 5 V TTL/CMOS logic families without level shifting |
| Active Current | 30 mA at 5 MHz, determines decoupling capacitor sizing (0.1 µF ceramic + 4.7 µF bulk per 8 devices) |
| Standby Current | 100 µA (CMOS E high), reduces system power in idle states for battery-backed or energy-sensitive applications |
| Programming Voltage | VPP = 12.75 V ±0.25 V, requires dedicated high-voltage supply rail and strict sequencing with VCC |
| UV Erase Dose | ≥15 W·s/cm² at 2537 Å, specifies minimum UV exposure for full bit reset to '1' state in FDIP28W package |
Pinout & Package
FDIP28W (28-pin ceramic frit-seal DIP with UV-transparent window) provides mechanical and optical access for field erasure. Pin numbering follows standard dual-in-line convention with notch orientation as shown in Figure 2A.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; A9 carries 11.5–12.5 V for Electronic Signature mode activation |
| Q0–Q7 | Data Outputs | 8-bit bidirectional data bus; outputs driven in read/verify; inputs latched during programming |
| E | Chip Enable | Primary device selection signal; CMOS high (VIH > VCC − 0.2 V) places device in 100 µA standby |
| G | Output Enable | Secondary output gate; controls Q0–Q7 drive state independent of E, preventing bus contention |
| VPP | Program Supply | 12.75 V programming voltage input; must be applied simultaneously with or after VCC and removed before or with VCC |
| VCC | Supply Voltage | 5 V ±10% read supply; 6.25 V ±0.25 V during programming; powers internal logic and output drivers |
| VSS | Ground | Reference return for all signals; requires low-inductance connection to minimize transient noise |
| NC | No Connect | Internally unconnected pins (e.g., PLCC32 pin 17); must remain floating or tied to VSS per layout guidelines |
| DU | Don't Use | Reserved terminals (e.g., PLCC32 pin 16); not bonded and electrically isolated-must not be connected |
Key Features
| Feature | Design Value |
|---|---|
| Two-line output control (E + G) | Enables zero-bus-contention memory arrays: E gates power, G gates output drivers-critical for multi-chip systems |
| Electronic Signature (ES) mode | Reads manufacturer code (20h) and device ID (8Dh) via A9 voltage forcing-ensures correct algorithm selection in universal programmers |
| PRESTO II programming algorithm | Guarantees margin-safe programming in ≤3.5 s via auto-verified 100 µs pulses-eliminates overprogramming risk |
| UV-erasable FDIP28W package | Transparent quartz window allows full chip erasure in 15–20 min under 2537 Å UV light-supports firmware iteration in lab environments |
| Wide temperature range | –40 °C to 125 °C operation (industrial grade) ensures reliability in motor drives, PLCs, and automotive ECUs |
Applications
| Industrial PLC Firmware Storage | Legacy Microprocessor Boot ROM |
|---|---|
|
Use Scenario: Storing ladder logic firmware and I/O configuration in programmable logic controllers deployed in factory automation cabinets. IC Role / Device Role / Timing Role: Nonvolatile boot memory mapped to CPU address space; accessed during power-on reset sequence with deterministic 100 ns read latency. Use Value: UV erasability enables field firmware updates without PCB rework; FDIP28W window permits rapid reprogramming between production batches. |
Use Scenario: Providing cold-start instruction code for Z80 or 8086-based embedded controllers in test equipment and medical analyzers. IC Role / Device Role / Timing Role: Primary boot ROM executing initial hardware initialization and jump-to-application vector; operates at 5 V with TTL-compatible timing. Use Value: 30 mA active current and 100 µA standby support low-power sleep modes while retaining program integrity across power cycles. |
| Automotive Engine Control Unit (ECU) | Avionics Configuration Memory |
|
Use Scenario: Holding calibration maps and sensor lookup tables in engine management systems subject to extended thermal cycling. IC Role / Device Role / Timing Role: Read-only configuration store accessed during closed-loop fuel injection control loops; rated for –40 °C to 125 °C ambient. Use Value: Ceramic FDIP28W package withstands thermal shock and vibration; electronic signature prevents incorrect firmware loading during service. |
Use Scenario: Retaining flight-critical configuration parameters in airborne navigation computers where long-term data retention is mandated. IC Role / Device Role / Timing Role: Radiation-tolerant nonvolatile memory storing aircraft-specific airframe coefficients and sensor offsets; erased only during depot-level maintenance. Use Value: Guaranteed 10-year data retention at 125 °C; UV erasure under controlled conditions ensures traceable, auditable firmware revision control. |
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-120DC | 120 ns access time; identical FDIP28W package; same 5 V ±10% supply and 12.75 V programming voltage | Slightly slower timing margin; suitable where system clock rates ≤8 MHz allow relaxed tAVQV | Select when existing board layout uses AMI footprint and 120 ns timing satisfies system setup/hold requirements |
| MX27C256-10PC | 100 ns access time; PDIP28 plastic package (no UV window); same 32K × 8 organization and TTL interface | OTP-only (no UV erasure); eliminates need for UV lamp but prevents field firmware updates | Choose for cost-sensitive, high-volume production where firmware is finalized and field reprogramming is unnecessary |
Compared with M27C256B-10F1, AM27C256B-120DC trades 20 ns speed for second-source availability in identical ceramic package, while MX27C256-10PC sacrifices UV erasability for lower cost and plastic packaging-making it viable only in sealed, firmware-finalized deployments.
Availability
M27C256B-10F1 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microprocessor boot ROM, and automotive ECU calibration map retention requiring stable component supply across extended product lifecycles.
Supply support for M27C256B-10F1 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 broad analog, digital, and mixed-signal portfolios.
The M27C256B belongs to ST's legacy EPROM product line, designed specifically for robust, long-lifecycle firmware storage in mission-critical industrial and automotive systems where UV field erasure and deterministic timing are mandatory.
FAQ
What UV wavelength and exposure time are required to fully erase M27C256B-10F1?
Full erasure requires short-wave ultraviolet light at 2537 Å wavelength with a minimum integrated dose of 15 W·s/cm². Using a standard 12,000 µW/cm² UV lamp, the device must be placed within 2.5 cm of the lamp tubes for 15–20 minutes. Room fluorescent lighting may cause partial erasure over years; direct sunlight can erase it in ~1 week.
Can M27C256B-10F1 be programmed in-system using standard 5 V logic levels?
No. Programming requires VPP = 12.75 V ±0.25 V applied to the VPP pin, VCC = 6.25 V ±0.25 V (not 5 V), and precise 100 µs enable pulses on the E pin. Standard 5 V microcontroller GPIO cannot generate these voltages or timing-dedicated EPROM programmers or high-voltage interface circuitry are mandatory.
How does the Electronic Signature mode function, and what pins are involved?
Electronic Signature mode reads Manufacturer Code (20h) and Device Code (8Dh) by applying 11.5–12.5 V to A9 while holding VCC = VPP = 5 V and all other address lines low. Toggling A0 between low and high sequentially outputs the two bytes on Q7–Q0. This mode operates only at 25 °C ±5 °C and is used by programmers for automatic algorithm selection.
Is the FDIP28W package RoHS-compliant, and are lead-free variants available?
The original M27C256B-10F1 FDIP28W package contains leaded solder and is not RoHS-compliant. STMicroelectronics discontinued RoHS conversion for this legacy EPROM family; no lead-free variant was released. For new designs, consider migration to modern SPI NOR flash with equivalent density and industrial temperature support.
M27C256B-10F1 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:
- 100 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-CDIP Frit Seal with Window
M27C256B-10F1 FAQ
1.How can I place an order for M27C256B-10F1 through Aetrix?
Please submit a Request for Quotation (RFQ) for M27C256B-10F1 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 M27C256B-10F1 reliable?
The price and inventory of M27C256B-10F1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C256B-10F1 is usually 5 days.
3.What payment methods are accepted for M27C256B-10F1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C256B-10F1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M27C256B-10F1?
M27C256B-10F1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M27C256B-10F1 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 M27C256B-10F1?
For technical support, including M27C256B-10F1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C256B-10F1 requirements.
6.How does Aetrix verify that M27C256B-10F1 is sourced from the original manufacturer or authorized distributors?
All M27C256B-10F1 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 M27C256B-10F1 meets industry standards.
7.What is the process for return or replacement of M27C256B-10F1?
All M27C256B-10F1 units undergo pre-shipment inspection (PSI). If there is an issue with M27C256B-10F1, 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 M27C256B-10F1 part is unused and in its original packaging.
Return procedure for M27C256B-10F1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M27C256B-10F1 Tags
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