ADI’s ADuCM355 precision analog MCU implements both potentiostat and electrochemical impedance spectroscopy (EIS) technology on a single chip

By Warren Miller,
contributing writer

Analog Devices Inc. (ADI)
recently introduced a new sensor interface that it claims
will be on the forefront of electrochemical sensory applications. The ADuCM355 precision analog
microcontroller (MCU) implements both potentiostat and electrochemical
impedance spectroscopy (EIS) functionality on a single chip to provide leading-edge
sensor diagnostics, as well as lower power consumption and noise output than
its predecessors, making it more reliable, versatile and cost effective than
other IC solutions, according to the company. 

The ADuCM355
with biosensor and chemical interfaces is specifically designed for measuring
and controlling chemicals and biosensors, making it well suited for industrial
gas sensing, instrumentation, vital signs monitoring and disease measurement.
It features two low-power potentiostats (8.5 µA, 1.6 µV RMS) and 3 or more sensor
electrodes, making it the only MCU currently on the market with those
specifications (according to ADI). It includes a 26-MHz core with 128 kB of
Flash memory and 64 kB of SRAM.

As specified in the
datasheet, the analog capabilities include a 16-bit, 400 kilo samples per
second multichannel successive approximation register (SAR) analog-to-digital
converter (ADC) with input buffers, a built-in anti-alias filter (AAF) and a programmable
gain amplifier (PGA). The current inputs include three transimpedance
amplifiers (TIA) with programmable gain and load resistors for measuring
different sensor types.

The analog front end
(AFE) also contains two more low-power amplifiers designed specifically for
potentiostat capability to maintain a constant bias voltage to an external
electrochemical sensor. The noninverting inputs of these two amplifiers are
controlled by on-chip dual output digital-to-analog converters (DACs). The analog
outputs include another high-speed DAC and output amplifier designed to
generate an AC signal. 



Looking at the block diagram of the device (shown above),
the ADUCM355 isn’t stingy with other popular sensor-oriented peripherals.
General-purpose timers, often used for managing data collection on a precise
schedule, are available, along with a watchdog timer useful in applications
where safety and reliability are concerns. A range of communication peripherals
can be configured as required in a specific application and include a UART,
I2C, SPI and GPIO ports. The GPIO, combined with the general-purpose timers,
can generate a pulse width modulation (PWM) type output.

The ADuCM355, housed
in a 6-mm x 5-mm, 72-pin LGA package, is priced at $5.90 in quantities of
1,000. For more information on the product, visit the ADuCM355