M24LR16E Dual-Interface Wireless EEPROM
18 Feb 12
STMicroelectronics has come up with a
new method for data storage with a dual-interface wireless EEPROM memory IC,
This device can operate normally with a standard low power I2C
interface or it can switch over to a 13.56-MHz ISO15693 contactless RF
interface for wireless communication.
The antenna used for the two-way data
transfer in the RF interface mode has a dual purpose. Beyond transfering data, its second purpose is to
harvest ambient energy in the RF signal being transmitted, and use that to
supply its own power, and convert the excess into a voltage output that may be
used to power other electronic components.
While operating in the RF energy harvesting
mode and I2C disabled, an entire low-power system can be powered directly from
harvested RF energy. No battery or external power supply would be required for
this, since no power would be needed on the Vcc pin. In case the RF field
strength is insufficient or when the energy harvesting mode is disabled, the
analog output pin Vout goes into high-Z state and the energy harvesting mode is
this device would simplify the development and maintenance of many applications,
as the need for batteries, power cables, and data lines is eliminated. This
would have potential for many new applications, as new designs can be much
smaller and lighter, and much less expensive. It is possible for a system to
become virtually maintenance-free by using this method.
Some of the potential
applications would include e-paper devices such as electronic shelf labels,
sensing and monitoring systems, industrial automation, and personal healthcare
products. It is anticipated that this type of device would be widely used in
RFID/NFC-compatible devices as RFID is becoming standardized in supply-chain
and retail businesses. NFC technology is another possibility, as it is
estimated to be used in more than 500 million mobile phones sold annually by 2015.
power management circuitry integrated in the M24LR16E makes the extra harvested
energy available to other devices on the board through an output pin. The
nominal output voltage output on this pin is between 1.7 and 2.3V, which is
sufficient to power a few low-power ICs, such as CMOS chips. The maximum output
current on this pin can be configured from 300µA to 6mA by setting bits in an
M24LR16E-R also features a user configurable digital out pin (RF WIP/BUSY) that
can be used to drive a micro controller interrupt input pin. This pin is activated only when power is
applied to the Vcc pin, and can be set to toggle for RF write in progress, or
RF busy (command in progress), depending on the mode selected.
EEPROM memory in the M24LR16E is 16Kbits, and it is organized as 2048 x 8 bits
in the I2C mode and 512 x 32 bits in the ISO 15693 and ISO 18000-3 mode 1 RF
The memory device includes a data protection scheme to protect stored
data against threats such as accidental over-writing and unauthorized access or
tampering. There are several password protection options included, up to 32
The device operates at a 1.8V to 5.5V supply-voltage range and is
available in SO8, TSSOP8 or MLP8 surface-mount packages. The antenna required
for wireless operation can simply be etched on the printed circuit board.