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HomeProductsIntegrated Circuits (ICs)MemoryMD27C64-20/B
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MD27C64-20/B - Rochester Electronics, LLC

Manufacturer Part Number
MD27C64-20/B
Manufacturer
Rochester Electronics
Allelco Part Number
32D-MD27C64-20/B
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
10,279 pcs available, New & Original
Parts Description
64K (8K X 8) EPROM
Package
Bulk
Data sheet
-
RoHs Status
 
Compare
Our certification
In stock: 10279
  • Unit Price: $165.74
  • Subtotal: $0.00

Want a better price?
Add to Cart and Submit RFQ now, we'll contact you immediately.

Quantity Unit Price Ext. Price
1+ $165.74 $165.74
200+ $66.13 $13,226.00
500+ $63.92 $31,960.00
1000+ $62.83 $62,830.00
The above prices does not include taxes and freight rates, which will be calculated on the order pages.

Specifications

MD27C64-20/B Tech Specifications
Rochester Electronics, LLC - MD27C64-20/B technical specifications, attributes, parameters and parts with similar specifications to Rochester Electronics, LLC - MD27C64-20/B

Product Attribute Attribute Value
Manufacturer Rochester Electronics
Series -
Product Attribute Attribute Value
Package Bulk
Base Product Number MD27C

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status Not applicable
Moisture Sensitivity Level (MSL) 3 (168 Hours)
REACH Status Vendor Undefined
ECCN EAR99
HTSUS 8542.32.0061

Parts Introduction

Manufacturer Part Number

MD27C64-20/B

Manufacturer

rochester-electronics

Introduction

The MD27C64-20/B is a 64Kbit UV erasable and programmable read-only memory (EPROM) designed for storage applications where fast and reliable data storage is essential.

Product Features and Performance

UV erasable and programmable memory

Non-Volatile EPROM technology

64Kbit memory size

Organized as 8K x 8 bits

Parallel memory interface

Access time of 200 ns

Product Advantages

Reliable data retention

Fast access time enhances system performance

Easily erasable with UV light for reprogramming

Key Technical Parameters

Memory Type: EPROM UV

Memory Size: 64Kbit

Memory Organization: 8K x 8

Access Time: 200 ns

Voltage Supply: 4.5V ~ 5.5V

Operating Temperature: 0°C ~ 70°C (TA)

Quality and Safety Features

Robust through-hole packaging for secure mounting

Operates effectively within industrial temperature ranges

Compatibility

Compatible with systems requiring 28-CDIP packaging

Interfaceable with most processors using a parallel memory interface

Application Areas

Embedded systems

Microcontroller-based systems

Robotics

Industrial automation systems

Product Lifecycle

Currently active product status

Not nearing discontinuation

Replacement and upgrade options are available

Several Key Reasons to Choose This Product

Proven EPROM UV technology offers durability and ease of use

High data storage capacity for extensive program storage

Rapid access speed aids in faster data retrieval, optimizing system performance

Sturdy and reliable design suitable for various industrial applications

Frequently Asked Questions(FAQ)

How does the MD27C64-20/B compare to modern flash-based alternatives in terms of endurance and reusability for embedded firmware applications?
The MD27C64-20/B is a UV-erasable EPROM with a typical erase cycle life of 1,000 cycles, making it suitable only for development or low-volume production where occasional reprogramming is acceptable. In contrast, modern NOR flash memory devices can endure over 100,000 erase/write cycles and support byte-level updates without full block erasure. For firmware storage in production systems requiring frequent code updates, flash offers superior durability and flexibility. However, the MD27C64-20/B remains relevant in legacy systems or environments where radiation-hardened or non-volatile write protection is required without electrical interference.
What are the key timing constraints when interfacing the MD27C64-20/B with a 5V microcontroller running at 8 MHz, and how do they affect system design?
The MD27C64-20/B has an access time of 200 ns, which corresponds to a maximum clock frequency of approximately 5 MHz if used in a synchronous read configuration. An 8 MHz microcontroller exceeds this limit, potentially causing data corruption during random access operations. To safely interface the device, designers must either use wait states or operate the microcontroller at a reduced clock speed. Alternatively, a buffer register or FSR (Fast Static RAM) can be employed to capture valid data within the 200 ns window. This timing mismatch often leads to increased complexity in bus arbitration and may necessitate software delays or hardware handshake protocols.
Can the MD27C64-20/B be used in industrial automation systems operating in ambient temperatures up to 70°C, and what precautions should be taken?
Yes, the MD27C64-20/B is rated for operation from 0°C to 70°C, making it technically compliant with industrial environments at the upper end of its specified range. However, prolonged exposure near 70°C may accelerate oxide degradation in the floating-gate transistors, potentially reducing data retention beyond the guaranteed 10-year minimum. Designers should ensure adequate thermal dissipation and avoid localized hotspots. Additionally, since the device uses through-hole mounting, mechanical stress from vibration or thermal cycling in harsh environments could compromise solder joints—especially in 28-CDIP packaging, which lacks surface-mount compatibility.
How does the supply voltage tolerance of the MD27C64-20/B (4.5V–5.5V) impact compatibility with 3.3V logic systems?
The MD27C64-20/B operates at 5V nominal supply but accepts down to 4.5V, which is incompatible with standard 3.3V logic families. Direct connection risks damaging the memory device due to overvoltage on input pins. To interface with 3.3V systems, level-shifting circuitry such as bidirectional voltage translators or resistive divider networks must be implemented. However, these introduce signal integrity concerns, especially given the 200 ns access time, where propagation delay and rise/fall time mismatches can corrupt data transitions. Designers should also verify that control signals like CE# and OE# meet VIH thresholds when driven from 3.3V sources.
What distinguishes the MD27C64-20/B from other members of the MD27C series, and why might one choose this specific part number?
The MD27C64-20/B belongs to the MD27C series by Rochester Electronics, characterized by 64Kbit (8K x 8) EPROM density and parallel interface. The "-20" suffix denotes a 200 ns access time, distinguishing it from faster variants like the -12 (120 ns) or slower -25 (250 ns). Selection depends on system timing budgets; for example, a CPU with a 200 ns memory cycle limit cannot use the -12 without risking setup violations. The "/B" variant typically indicates bulk packaging and possibly extended lead times, reflecting its role as a long-term availability (LTA) component rather than a mainstream commodity part.
Is it feasible to program the MD27C64-20/B in-circuit without removing it from the board, and what challenges arise?
No, the MD27C64-20/B requires removal and exposure to ultraviolet light via its quartz window for erasure before reprogramming. In-circuit programming is not supported because the package lacks UV transparency in mounted form. Attempting field updates without desoldering introduces logistical complexity and risks damage during handling. Furthermore, repeated erase/program cycles degrade the oxide layer, reducing endurance. For production environments demanding updatable firmware, alternative technologies such as EEPROMs or serial flash with in-system capability are preferable despite higher cost per bit.
How does the moisture sensitivity level (MSL 3) of the MD27C64-20/B influence storage and assembly practices in high-humidity facilities?
With an MSL rating of 3, the MD27C64-20/B must be stored in dry ambient conditions (≤60% RH) and reflowed within 168 hours after unsealing. While this device is through-hole and thus less prone to popcorning than surface-mount parts, prolonged exposure to moisture can still cause internal delamination or corrosion in the CDIP package’s ceramic substrate. Facilities assembling large batches should maintain controlled humidity and track open-bag timelines rigorously. Although not RoHS-compliant, its leaded construction avoids SAC alloy reflow issues, simplifying handling compared to lead-free alternatives—but complicating disposal under EU directives.
What are the implications of using the MD27C64-20/B in aerospace or military applications requiring radiation tolerance?
The MD27C64-20/B is not inherently radiation-hardened. Standard EPROMs like this are susceptible to single-event upsets (SEUs), where cosmic rays can flip bits in the floating-gate transistors. In space or high-altitude avionics, this leads to data corruption unless mitigated by error-correcting codes (ECC) or periodic checksum verification. For mission-critical systems, manufacturers specify hardened versions such as those from Texas Instruments or STMicroelectronics with proven SEU immunity. The MD27C64-20/B may find niche use in terrestrial military gear where environmental shielding reduces neutron flux, but it should not be assumed safe without qualification testing.
How does the parallel interface architecture of the MD27C64-20/B affect PCB routing complexity compared to serial alternatives?
The MD27C64-20/B uses an 8-bit wide parallel interface across 28 pins, demanding careful trace matching for signal integrity, particularly for address and data lines. At 200 ns access times, skew between D0–D7 can violate hold-time requirements if traces differ by more than ~1 ns over typical FR4 lengths. Serial flash devices eliminate most of these issues with differential signaling and lower pin counts. However, parallel EPROMs offer deterministic access latency and no protocol overhead, beneficial in real-time control loops where predictability outweighs pin count penalties. Designers must allocate extra PCB layers and spacing to minimize crosstalk in dense layouts.
Why would a designer choose the 28-CDIP package over SOIC or TSSOP equivalents for the MD27C64-20/B?
The 28-CDIP package provides robust mechanical stability and excellent thermal conductivity due to its ceramic construction, making it ideal for high-reliability or vibration-prone environments. Unlike plastic packages, CDIPs resist moisture ingress better and have lower outgassing, though they are heavier and harder to mount than SOICs. For through-hole designs requiring long-term reliability without reflow soldering, the CDIP is advantageous. The MD27C64-20/B’s base product number (MD27C) aligns with legacy industrial standards, ensuring compatibility with older test fixtures and socket-based programming tools common in repair labs.

Parts with Similar Specifications

The three parts on the right have similar specifications to Rochester Electronics, LLC MD27C64-20/B

Product Attribute MD27C64-25/B MD27C64-15/B MD27C64-20 MD27C256-25/B
Part Number MD27C64-25/B MD27C64-15/B MD27C64-20 MD27C256-25/B
Manufacturer Rochester Electronics, LLC Rochester Electronics, LLC Intel Rochester Electronics, LLC
Package - Tape & Reel (TR) Tube Tape & Reel (TR)
Series - - - -
Base Product Number - DAC34H84 MAX500 ADS62P42

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Customer Reviews

Evaluation: 10 Articles

  • Nath***rooks
    Jun 11, 2026

    Installed this power component in a converter board. Output remained stable under different load conditions and thermal performance was better than expected.

  • Dani***alkerTech
    Jun 1, 2026

    Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.

  • Yuki***aka88
    May 26, 2026

    信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。

  • Stev***aker
    May 20, 2026

    Solid diode for power rectification. Works well in switching circuits.

  • Bran***Lewis
    May 11, 2026

    Compact FPGA with good performance. Suitable for basic signal processing tasks.

  • Oliv***arris
    May 7, 2026

    Reliable I/O expander. Works well in embedded control applications.

  • Jess***Jones
    Apr 17, 2026

    It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.

  • Mich***Smith
    Apr 17, 2026

    Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.

  • Aman***arris
    Apr 3, 2026

    It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.

  • Mike***nch
    Apr 3, 2026

    Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.

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Shipment

Delivery Time

In-stock items can be shipped within 24 hours. Some parts will be arranged for delivery within 1-2 days from the date all items arrive at our warehouse. And Allelco ships order once a day at about 17:00, except Sunday. Once the goods are shipped, the estimated delivery time depends on the shipping methods and Delivery destination. The table below shows are the logistic time for some common countries.

Delivery Cost

  1. Use your express account for shipment if you have one.
  2. Use our account for the shipment. Refer to the table below for the approximate charges.
(Different time frame / countries / package size has different price.)

Delivery Method

  1. Global Common Shipment by DHL / UPS / FedEx / TNT / EMS / SF we support.
  2. Others more shipping ways, please get in touch with your customer manager.

Common Countries Logistic Time Reference
Region Country Logistic Time(Day)
America United States 5
Brazil 7
Europe Germany 5
United Kingdom 4
Italy 5
Oceania Australia 6
New Zealand 5
Asia India 4
Japan 4
Middle East Israel 6
DHL & FedEx Shipment Charges Reference
Shipment charges(KG) Reference DHL(USD$)
0.00kg-1.00kg USD$30.00 - USD$60.00
1.00kg-2.00kg USD$40.00 - USD$80.00
2.00kg-3.00kg USD$50.00 - USD$100.00
Note:
The above table is for reference only. There may have some data bias for the uncontrollable factors.
Contact us if you have any questions.
  • QC (Quality Warranty)
  • Payment Support
  • Packaging
  • Certifications & Memberships

QC (Quality Warranty)

Allelco is committed to exceeding customer expectations through customer service excellence, order accuracy, and on-time delivery.
This is achieved through our commitment to the continual improvement of our processes, services, and products.


Strict quality inspection builds a solid foundation for electronic component quality.
  1. Visual inspection
  2. Performance testing and reliability verification
  3. Standardized full-process testing
  4. Precise control of every parameter
We eliminate defective components and ensure the stable operation of electronic devices through professional quality standards.
Quality Inspection
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Payment Support

The payment method can be chosen from the methods shown below: Wire Transfer (T/T, Bank Transfer), Western Union, Credit card, PayPal.
  • HKBea
  • Paypal
  • MasterCard
  • Western-Union
  • VISA
Stable Delivery, Sincere Partnership — Your Faithful Supply Chain Partner
  • Efficient Supply Management
  • Cost-Saving Procurement
  • Fast Sourcing & Delivery
Contact us if you have any questions.

Packaging

Electrostatic Discharge Protection and Handling

All electrostatic-sensitive components are handled in accordance with electrostatic discharge control procedures. The products are hermetically sealed in anti-static safe packaging to prevent electrostatic damage. Appropriate labeling is also applied for identification and traceability. This ensures product integrity during storage, handling and transportation.


ESD

Certifications & Memberships

Third-party certified, strict quality control. Our certification
  • ISO 9001: 2015
  • ISO 13485: 2016
  • ISO 14001: 2015
  • ISO 28000: 2007
  • ISO 45001: 2018
  • GB/T 27922-2011
  • SMTA
  • IPC
  • ESD
  • PSMA

MD27C64-20/B

Rochester Electronics, LLC
32D-MD27C64-20/B

Want a better price? Add to Cart and Submit RFQ now, we'll contact you immediately.

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