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STMicroelectronics M27C256B-10B6
- Part No.:
- M27C256B-10B6
- Manufacturer:
- STMicroelectronics
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
M27C256B-10B6.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,022
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Product details
Overview
M27C256B-10B6 from STMicroelectronics is a 256 Kbit (32K × 8) UV-erasable EPROM in PDIP28 package, operating at 5V ±10%, with 100 ns access time, 30 mA active current, and 100 µA standby current. It features dual-line control (E/G), electronic signature (20h/8Dh), and supports programming at 12.75 V with 100 µs/word pulse width - used in legacy microprocessor boot memory and industrial firmware storage.
For engineers reviewing the M27C256B-10B6 datasheet, M27C256B-10B6 pinout, M27C256B-10B6 application, or M27C256B-10B6 equivalent, key selection criteria include UV-erase capability, TTL-compatible I/O timing, two-line output enable architecture, A9-based electronic signature verification, and compatibility with PRESTO II programming algorithms.
Technical Context
The M27C256B-10B6 implements a classic NMOS-derived EPROM architecture with address latching via A0–A14 (15-bit), parallel 8-bit data I/O on Q0–Q7, and separate chip enable (E) and output enable (G) for hierarchical bus control. Its two-line control logic ensures zero bus contention in multi-device memory arrays.
Programming requires precise voltage sequencing: VCC = 6.25 V ±0.25 V applied simultaneously with or before VPP = 12.75 V ±0.25 V; erasure relies on 2537 Å UV exposure (≥15 W·s/cm²). Electronic signature mode activates when A9 = 11.5–12.5 V with VCC = VPP = 5 V, outputting manufacturer code (20h) and device code (8Dh) on Q7–Q0.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - fixed parallel organization for 8-bit microprocessor data buses |
| Access Time | 100 ns - defines maximum clock rate for reliable read cycles in 5 MHz systems |
| Supply Voltage | 5 V ±10% - compatible with standard TTL/CMOS logic rails without regulation |
| Active Current | 30 mA at 5 MHz - determines decoupling capacitor sizing (0.1 µF ceramic per device) |
| Standby Current | 100 µA - enables low-power retention during processor idle states |
| Programming Voltage | 12.75 V ±0.25 V - required for Fowler-Nordheim tunneling; must be sequenced after VCC |
| Electronic Signature | Manufacturer Code 20h / Device Code 8Dh - enables automatic algorithm selection in programmers |
Pinout & Package
Package: PDIP28 (plastic dual in-line, 600 mil width, 28-pin, RoHS-compliant lead finish).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1–14, 16–19, 22, 24–27 | A0–A14, Q0–Q7, E, G, VPP, VCC, VSS | Standard address/data/control I/O; A0–A14 = 15-bit row/column decode; Q0–Q7 = bidirectional data bus |
| 15 | NC | No internal connection - must be left unconnected or tied to ground per layout best practice |
| 20 | A9 | Electronic signature activation pin - requires 11.5–12.5 V for ID readout; not used in normal operation |
| 21 | DU | Don't Use - internally unused; must remain floating or grounded per STMicroelectronics recommendation |
Key Features
| Feature | Design Value |
|---|---|
| UV Erasability | Enables full array reprogramming via 2537 Å UV light (15–20 min exposure); critical for firmware development iteration |
| Dual-Line Output Control | E (chip select) and G (output enable) allow hierarchical memory banking - eliminates bus contention in multi-chip systems |
| PRESTO II Programming | Guarantees margin-safe programming in ≤3.5 s using 100 µs pulses and auto-verify in margin mode |
| Electronic Signature | Hardware-level device identification (20h/8Dh) enables plug-and-play programmer compatibility without manual part selection |
| Wide Temperature Range | –40 °C to +85 °C (industrial grade) - validated for use in programmable logic controllers and motor drives |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Non-volatile boot memory mapped to CPU address space; accessed during power-on reset sequence. Use Value: UV-erasability allows field updates of control logic without PCB replacement; 100 ns access satisfies 8051/8085-based scan cycle timing. |
Use Scenario: Providing immutable startup code for 8-bit microcontrollers in medical diagnostic equipment. IC Role / Device Role / Timing Role: Primary ROM executing hardware initialization and watchdog setup prior to RAM initialization. Use Value: 100 µA standby current minimizes battery drain in backup-powered systems; electronic signature prevents firmware mismatch during reprogramming. |
| Automotive Engine Control Calibration | Avionics Display Bootloader |
|
Use Scenario: Holding engine calibration maps (fuel timing, spark advance) in early OBD-I compliant ECUs. IC Role / Device Role / Timing Role: Read-only memory bank accessed via multiplexed address/data bus under Z80 or 68HC11 CPU control. Use Value: –40 °C to +85 °C rating meets automotive under-hood thermal requirements; PDIP28 package enables through-hole reliability in vibration-prone environments. |
Use Scenario: Storing certified bootloader firmware for LCD display controllers in cockpit instrumentation. IC Role / Device Role / Timing Role: Secure, tamper-resistant boot source verified at power-up before loading application code from flash. Use Value: Electronic signature (20h/8Dh) provides cryptographic identity assurance; UV window allows post-certification patching under controlled lab conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-10DC | Same 256 Kbit × 8 organization, 100 ns access, but uses AMD's proprietary programming algorithm and signature codes (01h/8Dh) | Requires AMD-specific programmer firmware; no cross-programmer compatibility with ST tools | Select only if existing toolchain is AMD-locked; otherwise avoid due to signature mismatch risk |
| AT27C256B-10PU | Atmel version with identical pinout and AC specs, but higher 150 µA standby current and different erase threshold sensitivity | Slightly reduced UV endurance (100 vs. ST's 1000+ erase cycles); less tolerant of ambient fluorescent exposure | Acceptable for low-cycle prototyping; not recommended for field-deployed systems requiring long-term data retention |
Compared with AM27C256B-10DC and AT27C256B-10PU, the M27C256B-10B6 offers superior UV endurance, tighter standby current spec (100 µA), and native integration with ST's PRESTO II ecosystem - making it optimal for industrial firmware where reprogrammability and toolchain consistency are critical.
Availability
M27C256B-10B6 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and automotive engine control calibration requiring stable component supply across extended product lifecycles.
Supply support for M27C256B-10B6 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 over 40 years of non-volatile memory innovation.
The M27C256B belongs to ST's legacy EPROM product line, designed specifically for high-reliability, field-upgradable firmware storage in systems where flash memory was not yet mature or qualified - targeting industrial control, avionics, and automotive subsystems.
FAQ
What UV wavelength and exposure dose are required to fully erase the M27C256B-10B6?
Full erasure requires short-wave ultraviolet light at 2537 Å with a minimum integrated dose of 15 W·s/cm². Using a 12,000 µW/cm² lamp, place the device within 2.5 cm of the source for 15–20 minutes. Avoid ambient fluorescent lighting, which can cause partial erasure over months.
Can the M27C256B-10B6 be programmed in-system without removing it from the PCB?
No - in-system programming is not supported. Programming requires VPP = 12.75 V applied externally, precise voltage sequencing (VCC before VPP), and dedicated EPROM programmers with A9 voltage control for signature verification. The PDIP28 package is intended for socketed, bench-programmed use.
Why does the M27C256B-10B6 specify two different supply voltages for read (5 V) and program (6.25 V) modes?
The 6.25 V VCC during programming ensures sufficient gate oxide stress for reliable Fowler-Nordheim injection into the floating gate. Using 5 V would result in incomplete or marginal programming. The datasheet mandates strict sequencing: VCC must be applied before VPP and removed after VPP to prevent latch-up or cell damage.
Is the PDIP28 package of the M27C256B-10B6 RoHS-compliant?
Yes - the M27C256B-10B6 in PDIP28 (package code "B") uses lead-free terminations and complies with RoHS Directive 2011/65/EU. STMicroelectronics confirms this variant meets exemption 7a for high-melting-point solder alloys, with lead content < 0.1 wt% in finish layers.
M27C256B-10B6 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 28-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:
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
M27C256B-10B6 FAQ
1.How can I place an order for M27C256B-10B6 through Aetrix?
Please submit a Request for Quotation (RFQ) for M27C256B-10B6 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-10B6 reliable?
The price and inventory of M27C256B-10B6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C256B-10B6 is usually 5 days.
3.What payment methods are accepted for M27C256B-10B6?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C256B-10B6 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M27C256B-10B6?
M27C256B-10B6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M27C256B-10B6 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-10B6?
For technical support, including M27C256B-10B6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C256B-10B6 requirements.
6.How does Aetrix verify that M27C256B-10B6 is sourced from the original manufacturer or authorized distributors?
All M27C256B-10B6 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-10B6 meets industry standards.
7.What is the process for return or replacement of M27C256B-10B6?
All M27C256B-10B6 units undergo pre-shipment inspection (PSI). If there is an issue with M27C256B-10B6, 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-10B6 part is unused and in its original packaging.
Return procedure for M27C256B-10B6:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M27C256B-10B6 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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24LC01BT-I/OT
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M24C02-FMC6TG
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AT24CS02-SSHM-T
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93LC46BT-I/OT
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AT24C04C-SSHM-T
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24LC01BT-I/SN
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24AA02UIDT-I/OT
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