Energy consumed by serial MRAM


MR25H256It is a serial MRAM with a four pin interface of chip selection (CS), serial input (SI), serial output (so) and serial clock (SCK) using serial peripheral interface, which is logically organized as a memory array of 32kx8. SPI) bus. Serial MRAM implements a common command subset for SPI EEPROM and flash components today, allowing MRAM to replace these components in the same slot and interoperate on the shared SPI bus. Compared with available serial memory alternatives,Serial MRAMExcellent write speed, unlimited durability, low standby and running capacity, and more reliable data retention.


aboutMRAMBased on everpin technologies’ 256Kb serial spi MRAM mr25h256. Table 3 shows that when all the energy of the decoupling capacitor is used, the energy of each data byte is the lowest. The size of the decoupling capacitor should be selected to match the amount of data normally obtained by the system.


Energy consumed by serial MRAM


-The μ f capacitor allows 50 bytes (46 data bytes) to be written on the SPI bus at 40 MHz, while MRAM consumes 27 ma. This calculation is the source of the comparison using 46 bytes.


Energy consumed by MCU and LDO


aboutMCUIt may take 100 μ s to wake up, measure, and communicate the results to nonvolatile memory for necessary internal management. During this period, we assume that the active current consumption is 500 μ a (typical of a small MCU operating at about 5 MHz). Therefore, the energy consumption of each data acquisition is 3.3 V × 500 μ a × 100 μ s = 0.165 μ J.


In addition to the energy collected, we should also consider the energy required to keep the MCU active during nonvolatile memory writing. When data is not acquired or stored, MCU is in sleep state and consumes 5 μ a current. It is assumed that the power supply is an LDO and consumes 1 μ a current during all operating phases (activity and sleep).