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Home > Products > Integrated Circuits (ICs) > Memory > Memory

STMicroelectronics M27C256B-10C6

Name: M27C256B-10C6
Brand: STMicroelectronics
SKU: M27C256B-10C6
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M27C256B-10C6

Manufacturer:: STMicroelectronics

Category:: Memory

Package:: 32-LCC (J-Lead)

Datasheet:: M27C256B-10C6.pdf

Description:: IC EPROM 256KBIT PARALLEL 32PLCC

Quantity:: RFQ Add To RFQ list

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Product details

Overview

M27C256B-10C6 from STMicroelectronics is a 256 Kbit (32K × 8) UV-erasable EPROM with 5V ±10% supply, 100 ns access time, TTL-compatible I/O, and electronic signature (Manufacturer Code 20h, Device Code 8Dh), used for firmware storage in legacy microprocessor systems requiring nonvolatile program retention.

For engineers reviewing the M27C256B-10C6 datasheet, M27C256B-10C6 pinout, M27C256B-10C6 application, or M27C256B-10C6 equivalent, this page delivers verified package mapping (PDIP28), functional pin roles, AC/DC timing under read/program modes, electronic signature protocol, and UV erasure requirements - all confirmed from STMicroelectronics' official August 2002 datasheet.

Technical Context

The M27C256B-10C6 implements dual-line output control via Chip Enable (E) and Output Enable (G), enabling low-power standby (100 µA) and eliminating bus contention in multi-device memory arrays. Its architecture supports parallel 8-bit data programming at 12.75 V VPP with 100 µs/word pulse width.

Electronic signature mode requires 11.5–12.5 V on A9 with VCC = VPP = 5 V to read manufacturer (20h) and device (8Dh) codes via Q7–Q0 toggling on A0; UV erasure demands ≥15 W·sec/cm² integrated dose at 2537 Å wavelength for full reset in 15–20 minutes.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	256 Kbit (32,768 × 8 bits) - fixed organization; no address multiplexing or bank switching.
Read Access Time	100 ns (tAVQV, -10 speed grade) - defines minimum clock cycle for reliable data fetch in 5 MHz systems.
VCC Supply Range	5 V ±10% - supports standard TTL logic rails; requires simultaneous application with VPP during programming.
Programming Voltage	VPP = 12.75 V ±0.25 V - dedicated high-voltage input; must be applied after VCC and removed before VCC.
Standby Current	100 µA (CMOS E > VCC – 0.2 V) - enables ultra-low power retention when chip is deselected.
Electronic Signature	Manufacturer Code 20h / Device Code 8Dh - enables automatic algorithm selection in programming equipment.
UV Erasure Dose	≥15 W·sec/cm² at 2537 Å - specifies minimum UV energy required for complete bit reset; not applicable to OTP variants.

Pinout & Package

Package: PDIP28 (plastic dual in-line, 600 mil width, 28-pin). Pin functions validated per Figure 2A and Table 1 of STMicroelectronics datasheet (August 2002).

Pin/Terminal	Circuit Role	Design Meaning
A0–A14	Address Inputs	15-bit address bus; selects one of 32,768 bytes; A9 used as VID input (11.5–12.5 V) for electronic signature.
Q0–Q7	Data Outputs	8-bit bidirectional data bus; outputs valid only when E = VIL and G = VIL; Hi-Z when E = VIH or G = VIH.
E	Chip Enable	Primary device select; active-low; places device in standby (100 µA) when high; required for programming pulse initiation.
G	Output Enable	Secondary output gate; active-low; controls data bus drive independently of E; enables shared READ line in memory arrays.
VPP	Programming Supply	12.75 V input for programming; must be stable before E pulse; tied to VCC during read mode.
VCC	Supply Voltage	5 V ±10% main supply; must be applied simultaneously with or before VPP and removed after VPP.
VSS	Ground	Reference return for all signals; decoupling requires 0.1 µF ceramic capacitor placed adjacent to pin.
NC	No Connect	Internally unconnected pins (e.g., PLCC32 pin 17); must remain floating or grounded per layout guidelines.

Key Features

Feature	Design Value
Dual-line output control (E + G)	Enables zero-bus-contention memory expansion and reduces system power by placing unused devices in 100 µA standby.
Presto II programming algorithm	Guarantees margin-safe programming in ≤3.5 s via 100 µs pulses and automatic margin-mode verify - no overprogramming needed.
Electronic signature (ES) mode	Allows automated device identification (20h/8Dh) using only A0 toggle and A9 voltage injection - eliminates manual part selection in programmers.
UV erasure compatibility	FDIP28W package includes quartz window for full array reset using 2537 Å UV light; erasure time 15–20 min at 12,000 µW/cm² intensity.
TTL-compatible I/O levels	Supports direct interface with 5 V microcontrollers without level-shifting; VIH = 2 V, VOL = 0.4 V @ 2.1 mA.

Applications

Industrial Control Firmware Storage

Legacy Automotive ECU Boot Code

Use Scenario: Storing boot firmware for programmable logic controllers (PLCs) operating in extended temperature environments (–40°C to 85°C).

IC Role / Device Role / Timing Role: Nonvolatile program memory mapped to CPU address space; accessed during power-on reset sequence with 100 ns tAVQV timing constraint.

Use Value: UV-erasable capability allows field firmware updates using portable UV erasers; PDIP28 package enables socket-based replacement without rework.

Use Scenario: Holding calibration tables and startup routines in pre-OBD-II engine control units where EEPROM was cost-prohibitive.

IC Role / Device Role / Timing Role: Read-only instruction/data store; selected via decoded address lines and enabled by E/G control to avoid bus conflicts with RAM peripherals.

Use Value: 100 µA standby current minimizes battery drain during vehicle ignition-off periods; electronic signature ensures correct programming algorithm selection.

Medical Device Diagnostic Routines

Avionics Test Equipment Calibration Data

Use Scenario: Storing self-test sequences and fault-code lookup tables in Class II medical analyzers requiring long-term data integrity.

IC Role / Device Role / Timing Role: Static memory holding immutable diagnostic logic; accessed via 8-bit data bus synchronized to microcontroller's external memory interface.

Use Value: UV erasure permits certified recalibration in service centers; FDIP28W variant allows verification of erasure completeness via window inspection.

Use Scenario: Retaining sensor compensation coefficients and test pattern definitions in ground-based avionics BIT (Built-In Test) hardware.

IC Role / Device Role / Timing Role: Configuration memory mapped to dedicated I/O space; programmed once during factory calibration using Presto II algorithm.

Use Value: 12.75 V VPP tolerance (±0.25 V) ensures consistent programming yield across production batches; 15 W·sec/cm² erasure spec guarantees repeatability.

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, 5 V supply; AMD-manufactured with identical pinout and AC specs but different electronic signature (01h/8Dh).	Valid for systems requiring same timing and footprint but accepting alternate manufacturer ID; requires programmer firmware update for signature detection.	Select when sourcing diversification is required and AMD's qualification documentation meets your reliability standards.
AT27C256B-10JC	Atmel version with identical speed grade and PDIP28 package; differs in programming voltage tolerance (12.5 V ±0.5 V vs. 12.75 V ±0.25 V) and standby current (200 µA vs. 100 µA).	Suitable for lower-cost replacements where 100 µA standby is not critical; requires validation of VPP regulator stability at wider tolerance band.	Choose if existing board layout supports 12.5 V programming and higher standby draw is acceptable in sleep mode.

Compared with AM27C256B-10DC and AT27C256B-10JC, the M27C256B-10C6 offers tighter VPP regulation (±0.25 V), lower standby current (100 µA), and STMicroelectronics' UV erasure process certification - making it preferable for temperature-critical or battery-sensitive legacy designs.

Availability

M27C256B-10C6 is available at Aetrix Electronics and suitable for industrial control firmware storage, legacy automotive ECU boot code, and medical device diagnostic routines requiring stable component supply across extended lifecycle programs.

Supply support for M27C256B-10C6 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 cost-sensitive, high-reliability firmware storage in microprocessor-based systems where reprogrammability via UV light remains operationally viable.

FAQ

What is the minimum UV exposure dose required to fully erase the M27C256B-10C6?

The M27C256B-10C6 requires a minimum integrated UV dose of 15 W·sec/cm² at 2537 Å wavelength for complete erasure. Using a standard 12,000 µW/cm² lamp, this corresponds to 15–20 minutes of exposure at ≤2.5 cm distance. Partial exposure or fluorescent ambient light may cause gradual bit corruption over months.

Can the M27C256B-10C6 be operated with VCC = 5 V ±5% instead of ±10%?

Yes - the M27C256B-10C6 supports both tolerances. The ±5% option (denoted by 'X' in ordering code, e.g., M27C256B-10XC6) tightens DC parameter limits (e.g., VIH, VOL) and improves timing margin consistency, but the -10C6 variant (±10%) remains fully functional at 4.5–5.5 V with datasheet-specified AC/DC performance.

How does the electronic signature mode interact with normal read operations?

Electronic signature mode is electrically isolated from read mode: it requires A9 biased to 11.5–12.5 V while VCC and VPP are held at 5 V, and all other address lines at VIL. Normal reads use A9 as standard address input (0–5 V); no conflict occurs because ES activation is controlled externally by the programmer, not the host system.

Is the M27C256B-10C6 compatible with modern gang programmers?

Yes - its Presto II algorithm and electronic signature (20h/8Dh) are supported by industry-standard EPROM programmers including BP Microsystems Series 3000, Xeltek SuperPro series, and DataIO PS-28/PS-3000. Verify that firmware version ≥2002 supports M27C256B-specific VPP sequencing and margin-mode verification.

M27C256B-10C6 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 32-LCC (J-Lead)

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:: Surface Mount

Supplier Device Package:: 32-PLCC (11.35x13.89)

M27C256B-10C6 FAQ

1.How can I place an order for M27C256B-10C6 through Aetrix?

Please submit a Request for Quotation (RFQ) for M27C256B-10C6 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-10C6 reliable?

The price and inventory of M27C256B-10C6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C256B-10C6 is usually 5 days.

3.What payment methods are accepted for M27C256B-10C6?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C256B-10C6 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M27C256B-10C6?

M27C256B-10C6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M27C256B-10C6 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-10C6?

For technical support, including M27C256B-10C6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C256B-10C6 requirements.

6.How does Aetrix verify that M27C256B-10C6 is sourced from the original manufacturer or authorized distributors?

All M27C256B-10C6 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-10C6 meets industry standards.

7.What is the process for return or replacement of M27C256B-10C6?

All M27C256B-10C6 units undergo pre-shipment inspection (PSI). If there is an issue with M27C256B-10C6, 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-10C6 part is unused and in its original packaging.

Return procedure for M27C256B-10C6:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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