Machine Manufacturing

ZMD Introduces New Capacitive Sensor Signal Conditioner

February 24, 2011

The ZSSC3122 capacitive sensor signal conditioner benefits battery-powered, MEMS, industrial, and harsh environment applications.

DRESDEN, Germany -- ZMD AG (ZMDI), a global supplier of energy-efficient analog and mixed-signal solutions for automotive, industrial, and medical applications, has expanded its family of capacitive sensor signal conditioners (SSCs) with the addition of the wide-dynamic-range ZSSC3122 cLite device.

Thanks to new design technology, the chip delivers 14-bit resolution and 0.25% full-scale-output accuracy. A built-in sleep mode lowers current consumption to <1 µA for temperatures up to 85°C, making the ZSSC3122 ideal in low-power battery applications, as well as industrial and rugged environments. MEMS sensing elements, such as pressure sensors for hydraulic control systems, humidity sensors, and liquid level gauges also benefit from these features.

Capacitive sensors do not touch or make direct contact with the system being sensed, making them a preferred option for industrial linear and angular position sensors and contactless potentiometers, where harsh or explosive environments make other sensor technologies impractical.

Capacitive sensors are often favored for their small size and lower power consumption over resistive bridge sensors. The ZSSC3122 supports this view with an operating current as low as 60 µA over the entire voltage range of 1.8 V to 5.5 V.

Technical Features
The ZSSC3122 can be configured to interface with capacitive sensors from 2 to 10 pF with sensitivity as low as 125 atto-Farads (aF) per digital bit. The part accommodates single and differential input sensor configurations. All calibration is digital and completed in one pass, eliminating the cost of laser trimming and speeding production of fully calibrated sensor modules.

"As the flagship products of ZMDI, sensor signal conditioners demonstrate the precision, accuracy, operational efficiency and high performance that is designed in to every one of our devices," stated Steve Ramdin, Global Product Manager SSC at ZMDI. "Working closely with our customers, we have developed a digital technique to correct not only first-order, but third-order nonlinearity errors difficult or impossible to correct with a pure analog signal path. By providing third-order correction, we give our customers a device that is especially useful in humidity and pressure applications, as well as correcting for other sensor imperfections in almost any situation."

The ZSSC3122 connects to microcontrollers but can also be utilized in stand-alone designs for transducer and switch applications. The mixed-signal design of cLite offers 14-bit capacitive-to-digital conversion and full 14-bit compensation of sensor offset, sensitivity and temperature via an internal digital signal processor running a correction algorithm. Calibration coefficients are stored in an on-board non-volatile EEPROM. The system interface offers I2C, SPI, PDM or alarm outputs.

The standard supply voltage is 1.8 to 5.5 V with accuracy up to 0.25 % over a –40°C to +125°C range. Programming and single-pass calibration of the capacitive sensor and the ZSSC3122 is available through a standard PC environment using the ZSSC3122KIT development tools. The package includes TSSOP 14, a development board, USB cable and calibration software.

Pricing, Availability
The ZSSC3122 samples are available. Unit prices start at 3.30 EUR, or USD 4.54, in volumes of 1k devices. For high volume pricing, please contact your ZMDI sales representative.

About ZMDI
Zentrum Mikroelektronik Dresden AG (ZMDI) is a semiconductor company focused on energy efficiency. The company is a leading supplier of innovative, highly precise, robust and cost-efficient analog and mixed-signal semiconductors which allow for a maximum of energy efficiency and environmental protection in the automotive, mobile medical, industrial automation, and consumer markets. The company designs and markets application-specific standard products (ASSPs) and application-specific integrated circuits (ASICs) which are known for their robust, cost-effective performance in demanding environments characterized by high temperature, high voltage, and the need for ultra-low power.

Headquartered in Dresden, Germany, ZMDI has 280 employees worldwide and serves customers from its offices in Dresden, Stuttgart, Germany; Milan, Italy; Pocatello, ID, Melville, NY, USA; Tokyo, Japan and Taipei, Taiwan. ZMDI has design centers in Dresden, Stuttgart, Munich, Germany; Varna, Bulgaria and Madison, Wisconsin.

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