EERAM is a standalone SRAM memory with shadow EEPROM back-up on a single chip that helps automatically retain contents of the SRAM memory when system power is lost. The EERAM offers instant random writes to the array with no write cycle delay. The I2C EERAM family is available in 4 Kb and 16 Kb densities and comes in standard 8-pin SOIC, TSSOP and PDIP packages. EERAM is available in 3.0V and 5.0V options and in industrial and automotive temperature ranges (-40°C to 85°C and -40°C to 125°C) and is also available in automotive grade.
Comprised of two familiar and reliable memory technologies on a single chip, EEPROM and SRAM, EERAM offers a robust and dependable data solution that is also the lowest cost non-volatile SRAM solution. EERAM does not require an external battery to safely store data during a power loss event. Instead, a small, external capacitor is needed to provide the energy needed to store the contents of the SRAM on to the EEPROM when system power is lost.
The internal circuitry of the EERAM constantly monitors system power, upon power down or inadvertent loss of system power below the trip voltage (Vtrip) the contents of the SRAM is securely transferred to the EEPROM array using energy stored in an external capacitor connected to the Vcap pin (pin 1). Upon Power-Up, when the system voltage goes back above Vtrip, the contents of the EEPROM is transferred back to the SRAM array. This is the Auto STORE feature of the EERAM. The EERAM offers unlimited writes to the SRAM array and over 1M Erase/Write cycles to the EEPROM.
When Vdd falls below Vtrip (Power Off), content of SRAM is internally copied on to the EEPROM and capacitor provides energy to perform this operation. Stores can also be initiated manually via a Software Command or in Hardware by toggling Pin 7 (HS). Auto Store can be optionally disabled.
When Vdd gets back over Vtrip (Power On), content of EEPROM is automatically copied on the SRAM with internal on-chip circuitry at Power-Up - also known as the Auto Recall Operation. Device Auto Recalls automatically on power-up. Recalls can also be initiated in Software at any time. The EERAM also allows the user to perform manual store of the SRAM array either using the Hardware Store (HS) Pin (pin 7) or using the Software Store command. When these are executed, the contents of the SRAM are instantly copied on to the EEPROM. For users that don’t want to use an external capacitor on their board, the manual store functions provide flexibility to store SRAM array contents to the EEPROM as and when the user chooses.
The memory devices are now available in 8-pin SOIC, TSSOP and PDIP packages in volume production. The EERAM I2C PICtail Kit (AC500100 - pictured above) will be available in January 2017 from Microchip.
www.microchip.com/EERAM
