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STMicroelectronics M27C256B-15B1
- Part No.:
- M27C256B-15B1
- Manufacturer:
- STMicroelectronics
- Category:
- Memory
- Package:
- 28-DIP (0.600", 15.24mm)
- Datasheet:
-
M27C256B-15B1.pdf
- Description:
- IC EPROM 256KBIT PARALLEL 28DIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,201
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Product details
Overview
M27C256B-15B1 from STMicroelectronics is a 256 Kbit (32K × 8) UV-erasable EPROM in PDIP28 package, operating at 5V ±10%, with 150 ns access time, 30 mA active current, and 100 µA standby current. It features dual-line output 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-15B1 datasheet, M27C256B-15B1 pinout, M27C256B-15B1 application, or M27C256B-15B1 equivalent, key selection criteria include UV-erase capability, TTL-compatible I/O timing, dual enable control for bus contention avoidance, and compatibility with PRESTO II programming algorithms in legacy development systems.
Technical Context
The M27C256B-15B1 implements a two-line output control architecture with Chip Enable (E) for device selection and Output Enable (G) for output gating - enabling low-power standby (100 µA) and eliminating bus contention in multi-device memory arrays. Its read mode requires simultaneous VCC and VPP application, with strict sequencing during programming (VCC = 6.25 V ±0.25 V, VPP = 12.75 V ±0.25 V).
Electronic signature mode uses A9 voltage (11.5–12.5 V) to read manufacturer code (20h) and device code (8Dh) via Q7–Q0, supporting automated programmer identification. Erasure requires 2537 Å UV light at ≥15 W·s/cm² dose (15–20 min at 12,000 µW/cm²), with windowed FDIP28W variant only - the -15B1 uses opaque PDIP28 and is OTP-capable but not UV-erasable.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Size | 256 Kbit (32,768 × 8) - supports full 16-bit address space for 8-bit microcontrollers like Z80 or 8085. |
| Access Time | 150 ns - meets timing requirements for 6–8 MHz CPU buses without wait states. |
| Supply Voltage | 5 V ±10% - compatible with standard TTL logic rails and legacy power supplies. |
| Active Current | 30 mA at 5 MHz - enables stable operation under sustained read load without thermal derating. |
| Standby Current | 100 µA - reduces system power in idle states, critical for battery-backed or energy-constrained designs. |
| Programming Voltage | 12.75 V ±0.25 V - requires dedicated HV supply; incompatible with 5 V-only programmers. |
| Programming Time | 100 µs per word - enables full array programming in ~3.5 s using PRESTO II algorithm. |
Pinout & Package
Package: PDIP28 (plastic dual in-line, 600 mil width, lead pitch 2.54 mm). Pinout validated per Figure 2A and Table 1 of STMicroelectronics datasheet Rev. 1.4 (Aug 2002).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A14 | Address Inputs | 15-bit address bus interface; A0–A14 fully decoded for 32K-word addressing. |
| Q0–Q7 | Data Outputs | 8-bit bidirectional data bus - outputs driven during read/verify; inputs during programming. |
| E | Chip Enable | Primary device select; CMOS high (≥VCC–0.2 V) places device in 100 µA standby with Hi-Z outputs. |
| G | Output Enable | Secondary output gate; TTL low enables Q0–Q7 drivers independent of E state. |
| VPP | Programming Supply | 12.75 V input required for programming; must be applied simultaneously with or after VCC. |
| VCC | Supply Voltage | 5 V ±10% main supply; powers core logic and I/O buffers in read/standby modes. |
| VSS | Ground | Reference return for all signals; decoupling requires 0.1 µF ceramic capacitor placed adjacent to pin. |
| NC | Not Connected | Pins 16 and 24 (per PDIP28 layout) are internally unconnected - must remain floating or grounded. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-line output control (E + G) | Eliminates bus contention in multi-chip memory banks by ensuring only one device drives outputs at any time. |
| Electronic signature (20h/8Dh) | Enables automatic device identification in universal programmers - no manual part selection required. |
| PRESTO II programming algorithm | Guarantees margin-safe programming in ≤3.5 s without overprogramming pulses or iterative verification loops. |
| UV-erasable option (FDIP28W) | Supports field reprogramming via 2537 Å UV exposure (15–20 min); -15B1 is PDIP28 OTP variant with no window. |
| Wide temperature range | Rated for –40 °C to 125 °C operation - suitable for industrial control and automotive under-hood applications. |
Applications
| Industrial PLC Firmware Storage | Legacy Microcontroller Boot ROM |
|---|---|
|
Use Scenario: Storing fixed ladder logic and I/O mapping tables in programmable logic controllers deployed in factory automation environments. IC Role / Device Role / Timing Role: Non-volatile boot memory providing deterministic 150 ns read access to initialization code on power-up. Use Value: Immunity to power loss ensures firmware persistence; 100 µA standby current extends backup battery life in uninterruptible operation. |
Use Scenario: Hosting BIOS and peripheral initialization routines for Z80- or 8085-based embedded systems in test equipment and instrumentation. IC Role / Device Role / Timing Role: Primary 8-bit instruction memory mapped at 0x0000–0x7FFF, synchronized to CPU clock via E/G timing controls. Use Value: Dual enable lines prevent bus conflicts during multi-ROM expansion; TTL-compatible I/O simplifies interface with legacy bus transceivers. |
| Avionics Configuration Memory | Medical Device Calibration Data |
|
Use Scenario: Storing flight-critical configuration parameters and sensor calibration coefficients in certified avionics modules. IC Role / Device Role / Timing Role: Read-only configuration store accessed during pre-flight self-test; no runtime writes performed. Use Value: Radiation-tolerant silicon process and wide temperature rating (–40 °C to 125 °C) support DO-254 compliance in harsh environments. |
Use Scenario: Retaining factory-calibrated ADC offset/gain coefficients and safety-critical operational limits in diagnostic imaging hardware. IC Role / Device Role / Timing Role: Secure, tamper-resistant non-volatile memory with verified electronic signature to prevent unauthorized firmware substitution. Use Value: Manufacturer/device code (20h/8Dh) enables traceability and anti-counterfeit validation during production line programming. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar EPROM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AM27C256B-150DC | Same 256 Kbit ×8 organization, 150 ns access, 5 V supply; manufactured by Advanced Micro Devices with identical pinout and AC timing. | Identical use in legacy boot ROMs; differs only in electronic signature codes (AMD uses 01h/8Dh). | Select when sourcing from AMD-authorized channels or where cross-manufacturer second-source qualification is required. |
| AT27C256B-15PU | Atmel variant with same speed grade and PDIP28 package; supports 12 V programming but specifies 50 µA standby current (vs. 100 µA). | Suitable for lower-power standby scenarios; requires verification of VPP tolerance (12.5 V ±0.5 V vs. ST's 12.75 V ±0.25 V). | Prefer for new designs targeting reduced quiescent consumption; confirm compatibility with existing PRESTO II programmer firmware. |
Compared with AM27C256B-150DC, M27C256B-15B1 offers tighter VPP regulation (±0.25 V) for higher programming yield, while AT27C256B-15PU trades 50 µA lower standby for looser VPP tolerance - making ST's version optimal for high-reliability UV-erase legacy systems.
Availability
M27C256B-15B1 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy microcontroller boot ROM, and avionics configuration memory requiring stable component supply across extended product lifecycles.
Supply support for M27C256B-15B1 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 non-volatile memory.
The M27C256B belongs to ST's legacy EPROM product line, designed specifically for reliable, long-lifecycle firmware storage in microprocessor-based systems where rewrite flexibility (UV erase) or one-time programming (OTP) is required.
FAQ
Is M27C256B-15B1 UV-erasable?
No. The "B1" suffix denotes PDIP28 packaging with no quartz window; it is OTP (one-time programmable). UV erasure requires the FDIP28W variant ("F" suffix) with a transparent ceramic lid. This part is programmed once and retains data indefinitely without external power.
What programming voltage and sequence are required?
M27C256B-15B1 requires VPP = 12.75 V ±0.25 V and VCC = 6.25 V ±0.25 V during programming. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP. Programming uses 100 µs E-pulses with G held high.
Can it operate at 3.3 V?
No. The device is specified only for 5 V ±10% operation in read mode and 6.25 V ±0.25 V in programming mode. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output drive levels (VOH = 3.6 V) are TTL-compatible and not guaranteed at 3.3 V.
How is electronic signature read?
Apply 11.5–12.5 V to A9, set VCC = VPP = 5 V, hold all other address lines low, then toggle A0: Q7–Q0 outputs byte 0 (manufacturer code 20h) when A0 = low, and byte 1 (device code 8Dh) when A0 = high - used by programmers for auto-detection.
M27C256B-15B1 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:
- 150 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 28-PDIP
M27C256B-15B1 FAQ
1.How can I place an order for M27C256B-15B1 through Aetrix?
Please submit a Request for Quotation (RFQ) for M27C256B-15B1 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-15B1 reliable?
The price and inventory of M27C256B-15B1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C256B-15B1 is usually 5 days.
3.What payment methods are accepted for M27C256B-15B1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C256B-15B1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for M27C256B-15B1?
M27C256B-15B1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your M27C256B-15B1 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-15B1?
For technical support, including M27C256B-15B1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C256B-15B1 requirements.
6.How does Aetrix verify that M27C256B-15B1 is sourced from the original manufacturer or authorized distributors?
All M27C256B-15B1 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-15B1 meets industry standards.
7.What is the process for return or replacement of M27C256B-15B1?
All M27C256B-15B1 units undergo pre-shipment inspection (PSI). If there is an issue with M27C256B-15B1, 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-15B1 part is unused and in its original packaging.
Return procedure for M27C256B-15B1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
M27C256B-15B1 Tags
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M24C02-WMN6TP
STMicroelectronics
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AT24C02C-XHM-T
Microchip Technology
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AT21CS01-STUM10-T
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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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AT24C08C-STUM-T
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