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FAQ
General
• What is an EEPROM?
Short for Electrically Erasable Programable ROM, EEPROMs are a type of non-volatile memory that allows data to be written to each address via electric signals.
ROHM EEPROMs are capable of an industry best 1 million rewrites and retains data for up to 40 years. ROHM's unique double cell technology has been incorporated into the entire lineup, resulting in remarkably high reliability (zero accidental defects).
• What is an I2C-BUS?
A serial 2-line bus capable of 400kHz operation, it is the de facto standard interface and is widely used in digital consumer electronics, Bluetooth modules, and large household appliances.
Target Products:BR24L□□Series (PDF:788KB)
•What is an SPI BUS?
A serial 3-line bus capable of 5MHz operation, it is geared towards high-speed communications and is used primarily in vehicles, wireless LANs, DVCs, DSCs, and the like.
Target Products: BR25L□□0Series BR25H□□Series
• What is a Microwire BUS?
A serial 3-line bus capable of 2MHz operation, it is mainly used in vehicles, HDDs, and motherboards.
Target Products: BR93L□□Series BR93A□□Series BR93H□□Series
• What is double cell construction?
ROHM's unique high-reliability memory cell construction.
Generally, with competitors, one memory cell is allocated to each bit, resulting in data corruption if the memory cell becomes defective.
ROHM, on the other hand, allocates two cells for each bit. If one cell becomes defective the other takes over, preventing data corruption, protecting the customer's important data.
• What is an accidental defect?
This is when a defect occurs by chance in a memory cell during normal operation, resulting in memory corruption.
There are limitations on the number of times an EEPROM memory cell can be rewritten. ROHM guarantees the highest number of rewrites: 1 million times. Companies normally do not normally guarantee a chance defect will not occur within a number of times - they only confirm that all bits are normal at shipping.
ROHM has developed double-cell construction to reduce the rate of chance defects for greater data reliability.
Manufacturing conditions
• Discontinued Part Numbers
Please note that we cannot handle discontinued products. We ask that you look into replacement part numbers. Please refer to the discontinued part number list.
Specifications
• What situation is assumed when a power interruption occurs during a Write or Read operation in an EEPROM?
The built-in low-voltage write error protection circuit (LVcc circuit) is activated, preventing writing.
Power ON precaution: Please start up the Power On Reset (P.O.R.) circuit to ensure normal operation.
Target Products: BR24L□□Series BR25L□□0Series BR93L□□Series
• P.O.R. (Power On Reset) circuit
A function that resets the IC internally when the power is turned ON. When the power is turned ON the internal IC circuits and set pass through an unstable low voltage region as the Vcc rises, making it important to internally reset the IC during power up. The recommended conditions for operating the P.O.R. circuit are indicated the data sheet.
Target Products: BR24L□□Series BR25L□□0Series BR93L□□Series
• Does the 1 million data rewrites refer to each address or each page?
It refers to each address.
• What types of symptoms occur when the life-span for the number of rewrites is exceeded and a defect occurs?
Data corruption may occur.
• Does ROHM have EEPROM test results for a data retention period of 40 years? Does a 40-year data retention guarantee 40 years even after 1 million rewrites are exceeded?
Data is guaranteed for 40 years after the last rewrite has ended.
• The 5msec rewrite time is the time for writing how many bytes?
It is the amount of time for a single command input.
• What is the definition of write time?
• What will the write time be for each BUS?
I2C BUS
Write time is defined as the time it takes to write one byte/page.
Subject Product: The write time of the BR25L□□0 series is 5ms (max.).
• SPI BUS
Write time is defined as the time it takes to write one byte/page.
Subject Product: The write time of the BR25L□□0 series is 5ms (max.).
• Microwire Bus (BR93L□□ Series, BR93H□□ Series).
Write time is the time it takes to write one byte in one Write cycle (WRITE) as well as the time to write all addresses in a single Write All Addresses cycle (WRAL).
Subject Product: The write time of the BR93L□□ Series is 5ms (max.). The write time of the BR93H□□ Series is 10ms (max.).
• What about data at EEPROM shipment?
Target Products: BR24L□□Series → At shipping, data in all addresses FFh
BR25L□□0Series → At shipping, data in all addresses FFh
BR93L□□Series → At shipping, data in all addresses FFFh
BR24L□□ series software reset
Target Products: BR24L□□Series
• What does FAST-MODE and STANDARD-MODE regarding the BR24L□□ series mean?
Operation at 100kHz max. is called STANDARD-MODE, while FAST-MODE indicates operation at 400kHz max. &
Conditions: 1.8V≤Vcc<2.5V (100kHz max.), 2.5V≤Vcc≤ 5.5V (400kHz max.)
Target Products: BR24L□□Series
Environment-related
• What does RoHS-compliant mean?
That ROHM EEPROMs comply with the RoHS Directive.
Applications
Automotive
 |
· Engine management |
· ABS/ESP |
Consumer
 |
· Set-top boxes |
· VCR/DVD |
Industrial
 |
· Instrumentation |
· Oscilloscopes |
Communications
 |
· WLAN Wifi |
· Mobile |
Computers / Computer peripherals
 |
· Hard disk drives |
· Motherboards |
Modules
 |
· W-LAN(WiFi)module |
· Bluetooth module |
EEPROMs
A serial EEPROM(Electrically Erasable Programmable Read Only Memory) is non-volatile memory that can be overwritten electrically, in units of bytes, and is most suitable for data storage use.
ROHM's high reliability serial EEPROMs are among the top of their class. They command a large market share and are available in a range of capacities, bus interfaces (Microwire, I2C, SPI), operating voltages (1.8V to 5.5V, 2.5V to 5.5V) and package types, making them ideal for battery powered devices. In addition, the entire series utilizes unique double cell construction, significantly improving reliability, and are both lead-free and RoHS-compliant.
ROHM's serial EEPROMs are top shelf products featuring high reliability.
Unique double-cell construction and double reset functionality prevents data write errors, safeguarding your most important data. The highest quality is ensured through an integrated production process, from wafer to assembly.