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A Tiny but Mighty MEMS Infrared Temperature Sensor

Did you ever use your a laptop on your lap and get an unpleasantly warm sensation, even a burning, sensation, on the top of your legs?  Manufacturers of portable electronic devices would like to have a way of monitoring case temperature to insure that you don’t experience that sensation on your legs; or an unpleasantly warm hand if you’re using a handheld device.  But, until now, the only way to do that was to measure the temperature of the warmest component in the device and use that temperature to approximate the case temperature.  Now, TI has made it possible to measure case temperature directly using a very small, inexpensive MEMS infrared sensor. TI part number TMP006 is a MEMS infrared digital temperature sensor in a 1.6-mm x 1.6-mm package; approximately 1/16” x 1/16.  That is certainly remarkable! In this small package, the TMP006 integrates an on-chip MEMS thermopile sensor, signal conditioning, a 16-bit ADC (analog-to-digital-converter), a local temperature sensor, and voltage references.  This provides a complete digital solution for contactless temperature measurement.  The TMP006 uses only 240 uA quiescent current and 1 uA in shutdown mode.  It supports a temperature range of -40 degrees to +125 degrees C (Celsius) with an accuracy of +/- 0.5 degree C (typical) on the local sensor and accuracy of +/- 1 degrees C (typical) for the passive IR sensor.   It includes I2C/SMBus digital interface. Monitoring case temperature is not the only application for the TMP006.  It could also be used in a cell phone or other handheld device to measure the temperature of something outside the cell phone:  something cooking on a grill, a hot pan just out of the oven or any other temperature a person might want to know.  In addition, Semico believes that there are hundreds if not thousands of other potential applications in industrial or medical applications.  This is a temperature sensor that designers will find a way to use, often in unexpected ways. The sales price for this part in 1,000 piece quantities will be $1.50.  This suggests that the price will be much lower for volume purchases.  An evaluation module is available for for $50; and an IBIS model to verify board signal integrity requirements is also available, along with full source code for calculating object temperature and applications notes. This part is the kind of break-through part the semiconductor industry introduces from to time.  It is much smaller and less expensive than anyone could have imagined a remote temperature sensor could be.  At the same time, it has better performance that anyone could have expected in such a small package.  The fact that there are no specific applications for such a device in consumer applications is because until now a cost effective solution with low power consumption and small size was not available.  This is a new feature that system developers can exploit.  Semico believes that it will find numerous applications. Tony Massimini, CTO

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