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EERAM is a serial SRAM product that has hidden nonvolatile bits. On any power disruption, the active SRAM array content is moved to the nonvolatile bits.  When power is restored, the nonvolatile content is restored to the SRAM array and SRAM operation continues.

Nonvolatility at the Speed of SRAM


  • Unlimited Reads/Unlimited Writes: Standard SRAM cells and protocol with symmetrical read and write timing
  • Industry-Standard Bus Types: SPI, I2C
  • Invisible-to-User Data Transfers on Power Loss: Hidden nonvolatile cells capture SRAM content; power loss is detected automatically by the EERAM device
  • 100,000 Backups: Data can be moved from SRAM to nonvolatile cells > 100,000 times
  • 100-Year Data Retention: With power removed, data is kept safe for up to 100 years; when power is restored, data is moved back to SRAM for continuing operation
  • Quality: EERAM is based on high-volume, standard CMOS processes to create a very low-cost nonvolatile SRAM solution and the highest quality levels

EERAM in Two Minutes

Short value video explaining what EERAM is and how to use it.

SPI Serial EERAM Products by Density


I2C Serial EERAM Products by Density


What Is Serial EERAM?

Serial EERAM is a standalone serial SRAM memory that includes shadow nonvolatile backup. EERAM uses a small external capacitor to provide the energy needed to move the contents of the SRAM to the nonvolatile cells when system power is lost. Unlike NVSRAM, no external battery is needed. EERAM offers unlimited SRAM read and write cycles and > 100,000 backups to the nonvolatile cells. The Vcc is monitored inside the IC and can automatically handle the data movement between the SRAM and the nonvolatile memory on any power disruption.

  • 4 Kbit, 16 Kbit I2C
  • Nonvolatile (with small external CVCAP capacitor)
  • Standard symmetrical SRAM reads and writes
  • SRAM reads and writes can be random access or burst
  • Nonvolatile endurance (backups) > 100,000
  • Nonvolatile retention > 100 years

What Problem Does EERAM Solve?


EERAM offers unlimited writes to the SRAM array, allowing you to constantly write to the device. Since power loss events are typically random or unpredictable, EERAM works in applications that absolutely cannot lose the quickly changing SRAM data on any sudden power loss. It provides designers of data logging/black box or monitoring systems with a safe and accurate way to safely, reliably and automatically store the last data bytes prior to the power loss event. The capacitor connected to the VCAP pin provides the necessary energy to safely copy the RAM’s contents to the secure nonvolatile backup on power loss. Upon power-up, data is recalled automatically from the nonvolatile cells to the SRAM.

What Are the Benefits of EERAM?


  • Reliably preserves data through any power loss event
  • Automatically and safely stores data on power loss
  • Restores data automatically to SRAM on each power up
  • No battery needed
  • Unlimited reads and writes to standard serial SRAM memory
    • Write to the memory as often as you choose
    • Read from the memory as often as you choose
    • Writes and Reads can be random access one byte at a time or can be bursts of reads and writes
  • Lowest-cost nonvolatile SRAM solution by using standard CMOS memory cells for both SRAM and nonvolatile
    • Notably less expensive than competing FRAM and nvSRAM technologies
  • Low power consumption

EERAM in Smart Meters


Feature Benefit
Fast data-writing speed Protects against data loss in the event of a power failure
Read/write cycle endurance Permits data collection at frequent intervals
Back-up via capacitor Eliminates the need for a battery back-up to preserve data

EERAM in Automobiles


Application Why Is EERAM Needed?
Airbag Collects and stores info every second – blackbox
Telematics/Navigation Stores navigation waypoints, bookmarks, etc. for user data at ignition on
Entertainment Captures and holds changing station information so available at ignition on
Instrument Cluster Tracks elapsed miles
Tire Pressure Tire pressure logs (data logger)
ABS - Stability Control Holds data from ABS sensors – information such as speed, turn radius and wheel rotation
Power Train Adaptive system that manages the power train constantly; writes data to memory

Development Tools


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EERAM I²C PICtail™ Kit

Part Number: AC500100

The EERAM I²C PICtail Kit demonstrates the features and abilities of the 47C04 and 47L16 I²C EERAM devices. This daughter board provides both PICtail Plus and mikroBUS™ connectors for easy use with the Explorer 8 Development Board, the Explorer 16/32 Development Board, and many other tools.

Documentation


Title Download
AN2257 - Choosing the Right EERAM VCAP Capacitor Download
AN2047 - Recommended Usage of Microchip I2C EERAM Devices Download
Title Download
Memory Products Brochure Download
Title Download
I2C EERAM PICtail Daughter Board with mikroBus Connector Info Sheet Download
Title Download
Sample Code for EERAM PICtail Kit Download

Memory Product Comparison


  Serial
EEPROM
Parallel
EEPROM
OTP
EPROM
Serial
Flash
Parallel
Flash
Serial
SRAM
Serial
NVSRAM
Serial
EERAM
  Explore Products Explore Products Explore Products Explore Products Explore Products Explore Products  Explore Products Explore Products
Density 128 bit - 4 Mb 64 Kb - 1 Mb 256 Kb - 8 Mb 512 Kb - 64 Mb 1 - 64 Mb 64 Kb - 1 Mb 512 Kb - 1 Mb 4 Kb - 1 Mb
Clock Frequency 0.4 - 20 MHz 70 ns 45 ns 20 - 104 MHz 55-70 ns 16 - 20 MHz 16 - 20 MHz 1 - 66 MHz
Cost/Bit High High High Low Low Medium Medium Medium
Read Times Medium Fast Fast Medium Fast Medium Medium Medium
Write Times Medium Fast N/A Medium Fast Instantaneous Instantaneous Instantaneous
Pin Count 2 to 8 pins 28 and 32 pins 28 to 44 pins 8 pins 32 and 48 pins 8 pins 8 pins 8 pins
Data Retention 200+ Years 10 Years 10 Years 100+ Years 100+ Years Volatile 20+ Years
(with battery)
100+ Years
Typ. Standby Current 1 µA 200 µA 100 µA ~15 µA ~30 µA ~4 µA ~4 µA ~40 µA
Voltage 1.7 V - 5.5V 2.7V,
5V
2.7V,
5V
1.65V - 1.95V,
2.7V - 3.6V,
2.3V - 3.6V
1.65V - 1.95V,
2.7V - 3.6V,
4.5V - 5.5V
1.65V - 1.95V,
2.5V - 5.5V
2.5V - 5.5V 2.7V - 3.6V,
4.5V - 5.5V
Temperature -55°C to +150°C 1 -55°C to +125°C -40°C to +85°C -40°C to +125°C 1 -40°C to +85°C -40°C to +125°C -40°C to +85°C -40°C to +125°C 1

1. Selected densities