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STMicroelectronics M27C256B-90B6
- Part No.:
- M27C256B-90B6
- Manufacturer:
- STMicroelectronics
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
M27C256B-90B6.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,318
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Product details
Overview
M27C256B-90B6 from STMicroelectronics is a 256 Kbit (32K × 8) UV-erasable EPROM in PDIP28 package, operating at 5V ±10%, with 90 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 for embedded microprocessor memory applications.
For engineers reviewing the M27C256B-90B6 datasheet, M27C256B-90B6 pinout, M27C256B-90B6 application, or M27C256B-90B6 equivalent, key selection criteria include UV erasability, TTL-compatible timing, two-level output enable architecture, and verified 90 ns read performance across –40°C to 85°C.
Technical Context
The M27C256B-90B6 implements a two-line output control architecture with independent Chip Enable (E) and Output Enable (G) inputs, enabling low-power array design and eliminating bus contention. Its read mode requires both E and G low for valid Q0–Q7 output, with tELQV = tAVQV = 90 ns under standard AC conditions.
Programming uses 12.75 V ±0.25 V on VPP with 100 µs pulse width per word, while electronic signature verification relies on 11.5–12.5 V applied to A9 and toggling A0 to read 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 byte-wide microprocessor data buses |
| Access Time | 90 ns - guaranteed maximum address-to-output delay in read mode at VCC = 5V ±10% |
| Supply Voltage | 5V ±10% - single-supply operation compatible with legacy TTL/CMOS systems |
| Active Current | 30 mA at 5 MHz - defines power budget for active memory access in embedded controllers |
| Standby Current | 100 µA - enables low-quiescent-power hold state when E is high |
| Programming Voltage | 12.75 V ±0.25 V - precise high-voltage requirement for reliable Fowler-Nordheim tunneling |
| Electronic Signature | Manufacturer Code 20h / Device Code 8Dh - enables automatic algorithm selection in programming equipment |
Pinout & Package
Packaged in PDIP28 (plastic dual in-line, 600 mil width), the M27C256B-90B6 features 28 leads with 15 address inputs (A0–A14), 8 bidirectional data I/Os (Q0–Q7), and dedicated control pins including E (Chip Enable), G (Output Enable), VPP (programming supply), VCC, and VSS.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16 | A0–A14 | Address inputs selecting one of 32,768 memory locations; TTL-compatible voltage thresholds |
| 9 | VPP | 12.75 V programming supply input; must be stable before and after VCC during write cycles |
| 17, 18, 19, 20, 21, 22, 23, 24 | Q0–Q7 | Bidirectional data I/Os; output in read/verify, input during programming; drive TTL loads |
| 25 | G | Output Enable - controls Q0–Q7 tristate independently of chip selection; low enables outputs |
| 26 | E | Chip Enable - primary device select; high forces standby mode (100 µA ICC2) |
| 27 | VCC | +5V ±10% supply - powers logic and memory array; must be applied before/with VPP |
| 28 | VSS | Ground reference - common return for all internal circuits and I/O drivers |
Key Features
| Feature | Design Value |
|---|---|
| UV Erasable Architecture | FDIP28W variant allows full bit-pattern reset via 2537 Å UV exposure (15 W·s/cm²); PDIP28 variant is OTP-only |
| Dual-Line Output Control | E and G decouple device selection from output gating - reduces system power and prevents bus contention in multi-chip arrays |
| Electronic Signature | Read-only 2-byte ID (20h/8Dh) via A9 high-voltage activation - enables auto-algorithm matching in universal programmers |
| PRESTO II Programming | Guaranteed margin programming with 100 µs pulses and automatic verify in margin mode - eliminates overprogram risk |
| Wide Temperature Range | Rated for –40°C to +85°C (6 suffix) - validated for industrial control and automotive body electronics |
Applications
| Industrial PLC Memory | Legacy Automotive ECU Boot ROM |
|---|---|
|
Use Scenario: Storing firmware and lookup tables in programmable logic controller mainboards requiring field-upgradable nonvolatile storage. IC Role / Device Role / Timing Role: Byte-wide parallel boot ROM accessed by Z80 or 8051 derivatives during power-on initialization. Use Value: 90 ns access time ensures deterministic boot latency; UV erasability supports reprogramming after firmware validation. |
Use Scenario: Holding calibration maps and diagnostic routines in pre-OBD-II engine control units where flash was unavailable. IC Role / Device Role / Timing Role: Static memory mapped at fixed address range; enabled via discrete decoder driving E and G. Use Value: 100 µA standby current minimizes battery drain during vehicle sleep mode; TTL compatibility avoids level-shifting. |
| Military Communications Test Equipment | Medical Imaging System Firmware Storage |
|
Use Scenario: Storing FPGA configuration bitstreams and protocol stacks in ruggedized RF test instruments deployed in field environments. IC Role / Device Role / Timing Role: Nonvolatile storage interfaced to 16-bit bus with wait-state generation based on tAVQV = 90 ns. Use Value: Electronic signature (20h/8Dh) enables automated device verification during production programming and field recalibration. |
Use Scenario: Retaining safety-critical boot code and hardware initialization sequences in X-ray detector control modules. IC Role / Device Role / Timing Role: Read-only memory mapped into microcontroller address space; accessed only during cold start. Use Value: –40°C to +85°C rating ensures reliability across clinical ambient variations; PDIP28 package simplifies manual rework and replacement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EPROM memory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-90DC | Same 256 Kbit × 8 organization, 90 ns access, but uses AMD's proprietary programming algorithm and signature codes (01h/8Dh) | Requires AMD-specific programmer firmware; not interchangeable in PRESTO II-based systems | Select only if existing toolchain supports AMD signature and timing margins |
| AT27C256B-90PU | Atmel variant with identical pinout and 90 ns speed grade, but higher 120 µA standby current and different VPP tolerance (12.5 V ±0.5 V) | Marginally higher leakage may impact long-term battery-backed systems; requires VPP regulator adjustment | Prefer for new designs where Atmel programming ecosystem is standardized |
Compared with AM27C256B-90DC and AT27C256B-90PU, the M27C256B-90B6 offers tighter VPP regulation (±0.25 V), lower standby current (100 µA), and STMicroelectronics' PRESTO II algorithm - making it optimal for cost-sensitive industrial systems requiring field reprogrammability and verified UV erasure cycles.
Availability
M27C256B-90B6 is available at Aetrix Electronics and suitable for industrial PLC memory, legacy automotive ECU boot ROM, military communications test equipment, and medical imaging system firmware storage requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for M27C256B-90B6 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 analog, MCU, power, and memory solutions for industrial, automotive, and consumer markets.
The M27C256B belongs to ST's legacy EPROM product line, designed specifically for microprocessor-based systems requiring reliable, field-erasable nonvolatile storage with TTL interface compatibility and robust packaging options.
FAQ
Is M27C256B-90B6 UV-erasable or one-time programmable?
The M27C256B-90B6 uses the "B" suffix indicating PDIP28 packaging, which is OTP-only. UV erasure is only supported in the FDIP28W ("F") variant with a quartz window. This part cannot be erased by UV light and is intended for permanent program storage after initial programming.
What is the required VPP sequencing relative to VCC during programming?
VCC must be applied simultaneously with or before VPP, and removed simultaneously or after VPP. Violating this sequence risks incomplete programming or cell damage. The specified VPP is 12.75 V ±0.25 V, and VCC must be 6.25 V ±0.25 V during programming - not the 5 V used in read mode.
Can M27C256B-90B6 operate across the full –40°C to +125°C range?
No. The "6" in M27C256B-90B6 denotes the –40°C to +85°C industrial temperature grade. The +125°C rating applies only to the "3" suffix variant (e.g., M27C256B-90F3). Operating beyond +85°C risks timing violations and increased leakage current.
How does the electronic signature function differ from standard read mode?
Electronic signature requires applying 11.5–12.5 V to A9 (not VPP), with VCC = VPP = 5 V, and toggling A0 to read manufacturer code (20h) and device code (8Dh) on Q7–Q0. Standard read uses A9 as an address line and operates at TTL voltage levels - no high-voltage injection is involved.
M27C256B-90B6 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:
- 90 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-90B6 FAQ
1.How can I place an order for M27C256B-90B6 through Aetrix?
Please submit a Request for Quotation (RFQ) for M27C256B-90B6 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-90B6 reliable?
The price and inventory of M27C256B-90B6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C256B-90B6 is usually 5 days.
3.What payment methods are accepted for M27C256B-90B6?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C256B-90B6 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M27C256B-90B6?
M27C256B-90B6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M27C256B-90B6 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-90B6?
For technical support, including M27C256B-90B6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C256B-90B6 requirements.
6.How does Aetrix verify that M27C256B-90B6 is sourced from the original manufacturer or authorized distributors?
All M27C256B-90B6 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-90B6 meets industry standards.
7.What is the process for return or replacement of M27C256B-90B6?
All M27C256B-90B6 units undergo pre-shipment inspection (PSI). If there is an issue with M27C256B-90B6, 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-90B6 part is unused and in its original packaging.
Return procedure for M27C256B-90B6:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M27C256B-90B6 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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AT24C02C-SSHM-T
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
Microchip Technology
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24AA02UIDT-I/OT
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AT24C08C-STUM-T
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