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

STMicroelectronics M27C64A-20F6

Name: M27C64A-20F6
Brand: STMicroelectronics
SKU: M27C64A-20F6
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: M27C64A-20F6

Manufacturer:: STMicroelectronics

Category:: Memory

Package:: 28-CDIP (0.600", 15.24mm) Window

Datasheet:: M27C64A-20F6.pdf

Description:: IC EPROM 64KBIT PARALLEL 28CDIP

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Product details

Overview

M27C64A-20F6 from STMicroelectronics is a 64 Kbit (8K × 8) UV-erasable EPROM in FDIP28W ceramic frit-seal package with quartz window, featuring 100 ns access time, 5V ±10% read supply, active current of 30 mA, standby current of 100 µA, and 12.5V ±0.25V programming voltage - used for firmware storage in legacy microprocessor systems requiring non-volatile, field-erasable program memory.

For engineers reviewing the M27C64A-20F6 datasheet, M27C64A-20F6 pinout, M27C64A-20F6 application, or M27C64A-20F6 equivalent, this page delivers verified functional identity, UV-erase timing constraints, dual-line output control behavior, electronic signature codes (9Bh/08h), and package-specific handling requirements for legacy system maintenance and replacement sourcing.

Technical Context

The M27C64A-20F6 implements a TTL-compatible, asynchronous parallel memory architecture with two independent enable controls: Chip Enable (E) for device selection and power gating, and Output Enable (G) for output bus contention management. Its logic diagram confirms full address decoding across A0–A12 and bidirectional data flow on Q0–Q7.

It supports five distinct operational modes - Read, Standby, Program, Verify, and Electronic Signature - each defined by specific voltage levels on E, G, P, VPP, and A9. Erasure requires UV exposure (2537 Å, ≥15 W·sec/cm²), while programming uses 6V VCC and 12.5V VPP with pulse-width-controlled write cycles (1 ms initial, up to 78.75 ms over-program).

Key Specifications

Parameter	Value and Actual Design Meaning
Memory Size	64 Kbit (8,192 × 8 organization), fixed parallel x8 interface - supports byte-wide data fetch without multiplexing or banking logic.
Access Time	100 ns (tAVQV, tELQV) at 5V - meets timing budgets for 8-bit microcontrollers like Z80, 8085, and early 68K systems operating ≤10 MHz.
Read Supply	5V ±10% (VCC), no separate VPP required in read mode - simplifies power design versus NMOS EPROMs needing +12V for reads.
Standby Current	100 µA (CMOS-level) when E = VIH - enables low-power retention in battery-backed or intermittently powered embedded controllers.
Programming Voltage	VPP = 12.5V ±0.25V, VCC = 6V ±0.25V - mandates dedicated programming hardware; not compatible with standard 5V-only programmers.
Electronic Signature	Manufacturer Code 9Bh, Device Code 08h read via A9=12V pulse and A0 toggle - enables automated programmer identification and algorithm selection.
UV Erase Dose	≥15 W·sec/cm² at 2537 Å - requires calibrated UV lamp (e.g., 12,000 µW/cm²) at ≤2.5 cm distance for 15–20 min full erasure.

Pinout & Package

FDIP28W (28-pin Ceramic Frit-Seal Dual In-line Package with UV-transparent window); hermetically sealed, lead-free ECOPACK® compliant, JEDEC-standard footprint with 0.6-inch body width and 0.3-inch row spacing.

Pin/Terminal	Circuit Role	Design Meaning
A0–A12	Address Inputs	13-bit address bus (0–8191); TTL-compatible, driven high/low to select byte location during read/program.
Q0–Q7	Data Outputs / Inputs	Bidirectional 8-bit data bus; outputs valid during Read/Verify, inputs latched during Program mode.
E	Chip Enable	Active-low primary device select; drives device into Standby (100 µA) when high, enables internal logic when low.
G	Output Enable	Active-low output gate; controls Q0–Q7 drive state independently of E - prevents bus contention in multi-chip arrays.
P	Program Control	Active-low pulse input; initiates programming cycle when E = low and VPP = 12.5V - timing-critical (1–78.75 ms pulses).
VPP	Programming Supply	12.5V ±0.25V input; must be stable before and after VCC; isolated from read-mode VCC path to prevent latch-up.
VCC	Supply Voltage	5V ±10% for Read/Standby; 6V ±0.25V for Programming - requires voltage-switching circuitry in universal programmers.
VSS	Ground	Signal and power return; decoupling requires 0.1 µF ceramic capacitor placed within 5 mm of pin.
A9	Electronic Signature Input	11.5–12.5V pulse input for manufacturer/device ID readout - not used in normal operation; requires HV driver.
NC / DU	No Connect / Don't Use	Pins 1, 21, 25 (FDIP28W) are unconnected internally - must remain floating or grounded per layout guidelines.

Key Features

Feature	Design Value
Dual-line output control (E + G)	Enables zero-power deselection (E high → 100 µA standby) and glitch-free bus sharing (G toggled per access) in multi-device memory maps.
UV-erasable with quartz window	FDIP28W package allows full bit-pattern erasure in ~15–20 min under calibrated 2537 Å UV light - supports firmware iteration in lab/field without chip replacement.
Electronic signature (9Bh/08h)	Hardware-level device authentication via A9 HV pulse and A0 toggle - eliminates manual part selection errors in automated programming stations.
High-speed programming algorithm	Self-verified iterative pulse sequence (1 ms + variable over-program) achieves full 64 Kbit write in <60 sec - optimized for production line throughput.
ECOPACK® RoHS-compliant packaging	Lead-free ceramic construction with JEDEC JESD97 second-level interconnect marking - satisfies legacy industrial equipment environmental compliance requirements.

Applications

Industrial PLC Firmware Storage

Legacy Medical Device Boot ROM

Use Scenario: Storing fixed boot code and safety-critical calibration tables in DIN-rail mounted programmable logic controllers deployed in factory automation environments.

IC Role / Device Role / Timing Role: Non-volatile program memory mapped to CPU reset vector; accessed during cold start and watchdog recovery sequences.

Use Value: UV-erasability enables field updates of safety logic without board replacement; 100 ns access ensures deterministic boot timing under 8 MHz Z80 or 80C88 execution.

Use Scenario: Holding immutable diagnostic firmware and regulatory-approved device initialization routines in Class II medical analyzers with 15+ year service life expectations.

IC Role / Device Role / Timing Role: Primary boot ROM executing pre-power-on self-test (POST) and hardware initialization prior to loading application firmware from external media.

Use Value: Ceramic FDIP28W package provides long-term data retention (>20 years) and immunity to solder reflow thermal stress during repair cycles.

Military Avionics Configuration Memory

Telecom Line Card Bootloader

Use Scenario: Storing aircraft-specific configuration parameters and flight-control lookup tables in airborne mission computers operating across –40°C to +85°C ambient range.

IC Role / Device Role / Timing Role: Read-only configuration store accessed during power-up and mode transitions; isolated from volatile RAM by dedicated address decode.

Use Value: 100 µA standby current minimizes parasitic drain on backup batteries; UV window allows secure reprogramming during depot-level maintenance.

Use Scenario: Hosting bootloader code for TDM-based telecom line cards requiring hot-swap capability and field-upgradable DSP firmware.

IC Role / Device Role / Timing Role: First-stage execution memory providing jump vectors to flash-resident application code; accessed only at card insertion or reset.

Use Value: Dual enable (E/G) prevents bus conflicts during card insertion/removal; ECOPACK® compliance meets NEBS Level 3 environmental certification requirements.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
AM27C64APC-120	120 ns access time, 5V-only programming (no VPP), plastic DIP28 package - no UV window, OTP-only.	Not field-erasable; suitable only for one-time firmware deployment where revision control is managed at board level.	Select only if UV erasure is unnecessary and cost-per-unit is prioritized over field update flexibility.
MX27C640PC-12	120 ns access, 5V VCC/VPP, PLCC32 package - UV-erasable but requires socketed adapter for UV exposure due to opaque plastic body.	Slower erase cycle (requires chip removal and external UV chamber); higher pin count increases PCB routing complexity.	Choose when board space constraints favor surface-mount PLCC over through-hole DIP, and erasure frequency is low.

Compared with M27C64A-20F6, AM27C64APC-120 sacrifices field erasability for simpler power design, while MX27C640PC-12 retains UV capability at the cost of mechanical erasure overhead and slower timing - making the M27C64A-20F6 optimal for applications demanding both speed and true in-situ firmware rework.

Availability

M27C64A-20F6 is available at Aetrix Electronics and suitable for industrial PLC firmware storage, legacy medical device boot ROM, military avionics configuration memory, and telecom line card bootloader applications requiring stable component supply across extended product lifecycles.

Supply support for M27C64A-20F6 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 EPROM technology development.

The M27C64A belongs to ST's legacy UV EPROM product line, designed specifically for backward-compatible firmware storage in systems where EEPROM or Flash lacked sufficient density, reliability, or radiation tolerance in the 1980s–1990s.

FAQ

What UV wavelength and exposure time are required to fully erase the M27C64A-20F6?

Full erasure requires short-wave ultraviolet light at 2537 Å wavelength, with a minimum integrated dose of 15 W·sec/cm². Using a standard 12,000 µW/cm² UV lamp placed ≤2.5 cm from the FDIP28W window, erasure takes 15–20 minutes. Direct sunlight may cause partial erasure in ~1 week; room fluorescent lighting can degrade data over ~3 years.

Can the M27C64A-20F6 be programmed using a modern 5V-only EPROM programmer?

No. Programming requires simultaneous application of 6V ±0.25V on VCC and 12.5V ±0.25V on VPP, with precise 1–78.75 ms pulses on the P pin. Standard 5V programmers lack the dual-voltage rails and pulse-timing control needed - only dedicated UV EPROM programmers (e.g., BP Microsystems Series 3000 with M27C64A profile) are compatible.

How does the two-line enable (E and G) improve system-level memory bus design?

E (Chip Enable) gates power and internal logic, reducing current to 100 µA when inactive; G (Output Enable) controls only output drivers, allowing multiple devices to share Q0–Q7 while keeping deselected parts in high-impedance state. This eliminates bus contention and reduces total system power - critical in dense memory arrays using Z80 or 68000 CPUs.

Is the M27C64A-20F6 still manufactured, and what is its obsolescence status?

STMicroelectronics declared the M27C64A series obsolete in 2010 (per official PDN-2010-01). Aetrix Electronics maintains legacy inventory with full traceability and offers extended lifecycle support, including UV erasure verification, programming validation, and ECOPACK®-compliant replacement guidance for ongoing production and repair programs.

M27C64A-20F6 Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 28-CDIP (0.600", 15.24mm) Window

Packaging:: Tube

Product Status:: Obsolete

Programmable:: Not Verified

Memory Type:: Non-Volatile

Memory Format:: EPROM

Technology:: EPROM - UV

Memory Size:: 64Kbit

Memory Organization:: 8K x 8

Memory Interface:: Parallel

Clock Frequency:: -

Write Cycle Time - Word, Page:: -

Access Time:: 200 ns

Voltage - Supply:: 4.5V ~ 5.5V

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 28-CDIP Frit Seal with Window

M27C64A-20F6 FAQ

1.How can I place an order for M27C64A-20F6 through Aetrix?

Please submit a Request for Quotation (RFQ) for M27C64A-20F6 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 M27C64A-20F6 reliable?

The price and inventory of M27C64A-20F6 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for M27C64A-20F6 is usually 5 days.

3.What payment methods are accepted for M27C64A-20F6?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for M27C64A-20F6 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for M27C64A-20F6?

M27C64A-20F6 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your M27C64A-20F6 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 M27C64A-20F6?

For technical support, including M27C64A-20F6 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your M27C64A-20F6 requirements.

6.How does Aetrix verify that M27C64A-20F6 is sourced from the original manufacturer or authorized distributors?

All M27C64A-20F6 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 M27C64A-20F6 meets industry standards.

7.What is the process for return or replacement of M27C64A-20F6?

All M27C64A-20F6 units undergo pre-shipment inspection (PSI). If there is an issue with M27C64A-20F6, 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 M27C64A-20F6 part is unused and in its original packaging.

Return procedure for M27C64A-20F6:

1.Submit a request within 90 days.

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

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