locally gives the system designer multiple
tools to manage how data is securely
transmitted from the sensor node to the
central collector with its available power.
FRAM, with instant non-volatile writes
and low power operation, enables developers to maximize power efficiency for
Wearable electronics (Figure 2) is one
of the fastest growing Io T applications.
Wearables include smartwatches, fitness
trackers, sport watches, smart clothing,
and smart jewelry. Wearables incorporate
a processing unit, smart sensors, memory, and some form of communication
to allow access to the data in real-time.
Typically, these devices collect important
data such as number of steps, pulse rate,
sleep time, etc.
Like wearables, portable medical
devices are an emerging Io T application.
Adoption of connectivity in medical
devices is quickly transforming the
health care industry by making remote
sensors cost-effective. Consumers can
now monitor personal vital signs and
transmit data from their home, avoiding
costly visits to the doctor’s office. Portable
medical devices measure and store data
such as temperature, glucose levels, and
blood pressure locally. The data is then
transmitted periodically to the doctor’s
office for analysis. Measured data can be
evaluated locally by a microcontroller in
real-time, or it can be stored in a non-volatile memory, along with the date and
time stamp, for later processing.
With an emphasis on miniature size
and low power consumption, the type of
memory used becomes one of the key el-
ements in wearables and medical designs.
Multiple factors such as write endurance,
power consumption, and package size are
important considerations in selecting the
right memory. Key design factors include:
1. Endurance and density: To store
collected data, it’s important to use a
memory that has adequate density, as
well as sufficient endurance capable of
supporting constant logging of data.
2. Power consumption: Wearables and
portable medical devices typically op-
Figure 2: A wearable device
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FRAM EEPROM FLASH MRAM
Density 4 Kbit – 8 Mbit 1 Kbit – 2
512 Kbit – 1 Gbit 128 Kbit – 4
SPI Speed 108 MHz 20 MHz 133 MHz 104 MHz
Byte Write Yes No No Yes
1E+ 14 1E+ 6 1E+ 5 Unlimited
Active current 3. 2 mA 50
2 mA 5
40 mA 50 MHz 42 mA 40
Hibernate 0.10uA N/A N/A N/A
Data Retention 151 years
20 years 85°C 20 years
Table 1: Comparison of non-volatile memory technologies