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

STMicroelectronics M27W402-100B6

Name: M27W402-100B6
Brand: STMicroelectronics
SKU: M27W402-100B6
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M27W402-100B6

Manufacturer:: STMicroelectronics

Category:: Memory

Package:: 40-DIP (0.600", 15.24mm)

Datasheet:: M27W402-100B6.pdf

Description:: IC EPROM 4KBIT PARALLEL 40DIP

Quantity:: RFQ Add To RFQ list

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Inventory:2,855

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Product details

Overview

M27W402-100B6 from STMicroelectronics is a 4 Mbit (256K × 16) low-voltage UV-erasable EPROM with 100 ns access time at V_CC = 2.7–3.6 V, 15 µA standby current, and PDIP40 package. It operates across –40°C to +85°C, supports TTL-level addressing/data, and features dual-line control (E/G) for memory array power management in embedded microprocessor systems.

For engineers reviewing the M27W402-100B6 datasheet, M27W402-100B6 pinout, M27W402-100B6 application, or M27W402-100B6 equivalent, this device serves as a drop-in replacement for M27C4002 in legacy 16-bit bus systems requiring nonvolatile program storage with field-erasable capability via UV exposure.

Technical Context

The M27W402-100B6 implements a 262,144 × 16-bit organization with CMOS process technology, enabling operation down to 2.7 V while maintaining full read functionality and electronic signature compatibility with M27C4002. Its two-line output control (Chip Enable E and Output Enable G) enables precise bus contention avoidance and per-device power gating in multi-chip memory arrays.

Programming uses 12.75 V on V_PP and 6.25 V on V_CC with PRESTO II algorithm (100 µs/word), and erasure requires UV exposure (2537 Å, ≥15 W·s/cm²) through the windowed ceramic package - though the B6 variant uses PDIP40, indicating OTP configuration without UV window.

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	4 Mbit (262,144 × 16 bits) - supports 16-bit data bus microprocessor interfaces without byte-lane splitting.
Access Time	100 ns at V_CC = 2.7–3.6 V - ensures timing compliance with 10 MHz system clocks in read mode.
Supply Voltage (Read)	2.7 V to 3.6 V - enables direct interface with 3.3 V logic systems and extends battery life in portable designs.
Standby Current	15 µA max - reduces quiescent power in sleep-mode embedded controllers and instrumentation.
Operating Temp	–40°C to +85°C - qualified for industrial-grade deployment in motor drives, PLCs, and telecom line cards.
Input Leakage	±10 µA - minimizes address line loading and prevents unintended state transitions in high-impedance buses.
ESD Protection	2,000 V HBM - enhances robustness during handling and board-level assembly in non-ESD-controlled environments.

Pinout & Package

Package: PDIP40 (Plastic Dual In-line Package, 40-pin, 600 mil width, lead finish SnPb). Pinout validated per Figure 2A and Table 1 of STMicroelectronics datasheet (March 2000).

Pin/Terminal	Circuit Role	Design Meaning
A0–A17	Address Inputs	18-bit address bus supporting full 262,144-word decoding; A9 used for Electronic Signature voltage injection (12 V).
Q0–Q15	Data Outputs	16-bit bidirectional data bus - outputs only in Read/Verify modes; latched high-Z when E or G inactive.
E	Chip Enable	Primary device select; CMOS-high places device in 15 µA standby; TTL-low enables read/program access.
G	Output Enable	Secondary gate for Q0–Q15; allows shared G-bus across multiple EPROMs while keeping E decoded per device.
VPP	Program Supply	12.75 V ±0.25 V input required only during programming; must be applied simultaneously with or after V_CC.
VCC	Supply Voltage	2.7–3.6 V for read; 6.25 V ±0.25 V for programming - dual-voltage operation mandates strict sequencing control.
VSS	Ground	Dual VSS pins (pins 20 and 40) reduce ground bounce in high-speed read cycles and improve noise immunity.
NC	No Connect	Pins 21, 22, 33, 34 - internally unconnected; must remain floating or tied to VSS per layout guidelines.

Key Features

Feature	Design Value
UV Erasable / OTP Configurable	Same die offered in FDIP40W (UV-erasable) and PDIP40/PLCC44/TSOP40 (OTP); B6 suffix confirms OTP PDIP40 variant.
Electronic Signature	Manufacturer Code 0020h / Device Code 0044h readable via A9=12 V and A0 toggling - enables auto-algorithm selection in programmers.
Two-Line Output Control	Independent E (device select) and G (output gate) allow hierarchical memory enable - eliminates bus contention in >1-Mbyte arrays.
Low-Voltage Read Operation	Full functionality at 2.7 V enables direct integration into 3.3 V systems without level-shifting or regulator overhead.
PRESTO II Programming	Guaranteed margin programming with 100 µs pulses and automatic verify at elevated V_CC - eliminates over-programming risk.

Applications

Industrial PLC Firmware Storage

Legacy Medical Instrument Boot Memory

Use Scenario: Storing fixed firmware and calibration tables in programmable logic controllers deployed in factory automation cabinets.

IC Role / Device Role / Timing Role: Nonvolatile program memory mapped to CPU address space; accessed during cold boot and firmware updates via JTAG adapter.

Use Value: 100 ns access time meets timing budgets of 8051- and Z80-based controllers; OTP configuration prevents accidental reprogramming in field-deployed units.

Use Scenario: Holding diagnostic self-test routines and safety-critical initialization code in FDA-cleared patient monitoring devices.

IC Role / Device Role / Timing Role: Primary boot ROM executing before DRAM initialization; verified checksum read at power-on reset.

Use Value: –40°C to +85°C rating ensures reliability across clinical environments; 15 µA standby current extends battery backup duration during AC loss.

Avionics Display System BIOS

Telecom Line Card Configuration

Use Scenario: Storing display controller microcode and font assets in ruggedized cockpit multifunction displays.

IC Role / Device Role / Timing Role: Memory-mapped peripheral in PowerPC 603e subsystem; accessed via synchronous 16-bit bus with wait-state control.

Use Value: Dual VSS pins and 2,000 V ESD rating withstand vibration-induced noise and EMI in aircraft bays; PDIP40 simplifies manual rework.

Use Scenario: Storing port mapping, protocol stack parameters, and hardware revision IDs in carrier-grade DSLAM line cards.

IC Role / Device Role / Timing Role: Configuration store read once at card insertion; contents retained across hot-swap cycles and firmware upgrades.

Use Value: Pin compatibility with M27C4002 allows drop-in replacement in aging inventory; 262,144-word depth supports future feature expansion without PCB change.

Equivalent & Alternatives

The following parts are listed as comparable options for similar EPROM applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
AM27C400-120DC	5 V-only operation; 120 ns access; 28-pin DIP; no low-voltage support.	Requires level shifters in 3.3 V systems; incompatible with battery-powered designs.	Select only if legacy 5 V infrastructure exists and voltage translation is acceptable.
M27C4002-12F1	Identical pinout and electronic signature; 5 V supply; UV-erasable FDIP40W package.	Field-erasable via UV lamp; unsuitable for sealed enclosures or high-reliability OTP use cases.	Choose when reprogrammability is mandatory and UV access is physically feasible.

Compared with M27W402-100B6, AM27C400-120DC lacks low-voltage operation and increases system power budget, while M27C4002-12F1 sacrifices OTP security and industrial temperature range for erasability - making the M27W402-100B6 optimal for cost-sensitive, battery-aware, field-deployed 3.3 V systems requiring guaranteed one-time programming.

Availability

M27W402-100B6 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy medical instrument boot memory, and avionics display system BIOS requiring stable component supply and long-term obsolescence mitigation.

Supply support for M27W402-100B6 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 discrete solutions with broad analog and microcontroller portfolios.

The M27W402 belongs to ST's legacy EPROM product line, designed specifically for pin-compatible migration from 5 V EPROMs to 3.3 V systems while preserving existing PCB layouts and programming infrastructure.

FAQ

Is M27W402-100B6 UV-erasable or one-time programmable?

M27W402-100B6 is an OTP (one-time programmable) variant in PDIP40 package. Unlike the FDIP40W version, it lacks a quartz window and cannot be UV-erased. Programming is permanent after the initial write using 12.75 V on V_PP and 6.25 V on V_CC. This makes it suitable for production firmware where accidental reprogramming must be prevented.

What is the significance of the 'B6' suffix in M27W402-100B6?

The 'B' denotes PDIP40 package (plastic DIP, 40-pin), and '6' specifies the industrial temperature range (–40°C to +85°C). The '-100' indicates 100 ns maximum access time at V_CC = 2.7–3.6 V. This full ordering code confirms OTP configuration, 3.3 V compatibility, and extended thermal qualification - critical for deployment in harsh environments.

Can M27W402-100B6 be used as a direct replacement for M27C4002?

Yes - M27W402-100B6 is pin- and function-compatible with M27C4002, sharing identical electronic signature (0020h/0044h), address/data bus structure, and PRESTO II programming algorithm. However, it requires 2.7–3.6 V for read operations instead of 5 V, so level-shifting is unnecessary in 3.3 V systems but mandatory if interfacing with legacy 5 V buses.

What decoupling capacitors are recommended for M27W402-100B6?

STMicroelectronics recommends a 0.1 µF ceramic capacitor placed between V_CC and V_SS, located as close as possible to the PDIP40 pins, plus a 4.7 µF bulk electrolytic capacitor shared across every eight devices. This suppresses transient current spikes during E and G transitions, preventing supply rail collapse and output bus contention in multi-chip memory systems.

M27W402-100B6 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 40-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:: 4Kbit

Memory Organization:: 256 x 16

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: -

Access Time:: 100 ns

Voltage - Supply:: 2.7V ~ 3.6V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 40-PDIP

M27W402-100B6 FAQ

1.How can I place an order for M27W402-100B6 through Aetrix?

Please submit a Request for Quotation (RFQ) for M27W402-100B6 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 M27W402-100B6 reliable?

The price and inventory of M27W402-100B6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27W402-100B6 is usually 5 days.

3.What payment methods are accepted for M27W402-100B6?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27W402-100B6 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M27W402-100B6?

M27W402-100B6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M27W402-100B6 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 M27W402-100B6?

For technical support, including M27W402-100B6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27W402-100B6 requirements.

6.How does Aetrix verify that M27W402-100B6 is sourced from the original manufacturer or authorized distributors?

All M27W402-100B6 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 M27W402-100B6 meets industry standards.

7.What is the process for return or replacement of M27W402-100B6?

All M27W402-100B6 units undergo pre-shipment inspection (PSI). If there is an issue with M27W402-100B6, 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 M27W402-100B6 part is unused and in its original packaging.

Return procedure for M27W402-100B6:

1.Submit a request within 90 days.

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

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