E-field sensor IC finds new markets

Austin, Texas — Freescale Semiconductor today expanded its line of electric field (E-field) sensing integrated circuits (ICs) from automotive applications to the appliance and industrial markets.

Freescale claims it offers the only single-chip imaging IC that generates a low-level electric field and detects changes in that electric field. The IC generates a low-frequency sine wave, which is adjustable by using an external resistor and is optimized for 120 kHz. The MC34940 E-field IC is said to provide designers with greater functionality for creating embedded systems that require non-contact sensing.

The MC34940 E-field IC sensor can be used to implement proximity detection and three-dimensional E-field sensing. At the same time, it is able to trigger functions such as turning switches on or off, disabling features or setting off alarms to indicate dangerous situations for devices such as coffee pots, hair dryers and lawnmowers.

Manufactured with SMARTMOST technology, the MC34940 integrates support for up to seven simple electrodes, which can be used independently to provide information to perform multiple functions simultaneously. The device also supports up to 28 touch pad sensors.

For more demanding applications, the MC34940's on-board shield driver protects the electrode signal from any external disturbances. With coaxial cables, for example, electrodes can be remote while obtaining measurements as accurately as if the touch pads were in close proximity to the IC. The chip can also be embedded in glass or behind a touch panel for extreme temperatures and corrosive liquids.

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The original E-field imaging IC (MC33794), which came out in 2003, was developed via a joint effort between Freescale, the Massachusetts Institute of Technology’s (MIT) Media Lab and Elesys North America.

Major differences between the new and original IC include package size, number of electrodes, and the elimination of some of the automotive specific functions. The new device retains unique features such as the shield driver and tunable frequency and response time, which are useful in appliance and industrial applications.

The DEMO1985MC34940E evaluation kit is available now for $56.35 and includes the MC34940 evaluation board, driver CD-ROM, connectors and program software.

Offered in a 24-pin small outline integrated circuit wide (SOICW) package, the MC34940 is available now at a suggested resale price of $1.85 in 10,000-piece quantities. Click here for the MC34940 data sheet.

Freescale Semiconductor , 1-800-521-6274,

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