In a world where sensors monitor other sensors, the ability to condition multiple sensor inputs using a single IC makes sense. The multisensor interface circuit (MUSic) from ZMD America fits these applications.
The MUSic family targets low-power mobile electronic products using sensor-controlled microcontrollers, such as wearable medical instruments, portable navigation systems, and mobile products that use data from instruments like altimeters and barometers. Applications that depend on multiple high-precision sensors, such as industrial monitoring equipment, can take advantage of these devices as well.
“With these highly integrated sensor signal interface ICs, manufacturers can build highly innovative products in ultra-compact form factors and with very long battery-powered runtimes,” said Dirk Behrens, ZMD vice president of marketing.
The circuit amplifies and digitizes the multiple voltage signals of the connected sensors. The first device in the family, the ZMD21013, is optimized for resistive bridge-type sensors, though it may be adapted to other types (Fig. 1). Using the device’s multiplexer, one of three input channels and the associated measurement mode are selected at a given time (Fig. 2).
The mixed-signal MUSic devices include a programmable-gain amplifier, a programmable 16-bit delta-sigma analog-to-digital converter (ADC), multiple analog and digital filters, and a power-optimized analog sampling architecture. They output the measured value on the serial peripheral interface (SPI) that would typically be connected to an external MCU or DSP. The ZMD21013 provides additional temperature measurement capabilities, and its auto-zero mode monitors offset drifts and compensates/corrects for them.
Other features include an on-chip clock generator and a 16 by 8-bit EEPROM for storing configuration and calibration data and a user-programmable ID. Integration of this chip should reduce the bill of materials, product dimensions, and power consumption. In fact, the ZMD21013 promises to use around 30 µW during normal operations and less than 1 µW in idle mode.
The ZMD21013 will be available soon in both the consumer and industrial temperature operating ranges in a 4.4- by 4.6-mm TSSOP20 package. Engineering samples are now available. Full production is expected in the next few months at $2.10 in volumes of 1000 or more.