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Texas Instruments Says…
TMP006: MEMS Innovation Brings IR Temperature Measurement To Portables
Single-chip IR MEMS temperature sensor will enable new user apps, device features
Texas Instruments Incorporated (TI) is enabling contactless temperature measurement for the first time in portable consumer electronics with the industry’s first single-chip passive infrared (IR) MEMS temperature sensor. The TMP006 digital temperature sensor provides manufacturers of mobile devices, such as smartphones, tablets and notebooks, with the ability to accurately measure device case temperature using IR technology. This advancement over the current approach of approximating case temperature based on system temperature will enable system designers to optimize performance while providing a more comfortable user experience. The TMP0006 can also be used to measure temperature outside the device, enabling new features and user applications.
“The TMP006 solves our customers’ need for advanced thermal management of processors, and allows for optimizing system performance and safety even as processing power increases and form factors continue to shrink,” said Steve Anderson, senior vice president of TI’s High Performance Analog business. “And with the TMP006, for the first time mobile device manufacturers will be able to measure the temperature of objects outside the phone, which will unleash an entirely new functionality for apps developers to creatively tap into.”
The TMP006 is the most highly-integrated device of its kind. It integrates an on-chip MEMS thermopile sensor, signal conditioning, a 16-bit analog-to-digital-converter (ADC), local temperature sensor and voltage references on a single 1.6-mm x 1.6-mm chip. It provides a complete digital solution for contactless temperature measurement that is 95 percent smaller than any other thermopile sensor.
Probably the most popular non-contact infrared temperature sensor in recent years has been the Smartec SMT-IR99xx series (Smartec is a Dutch company) that produces a non-linear output voltage from a thermopile formed by a series of thermojunctions made from BiSb and NiCr deposited on a silicon substrate. An absorption layer (black) on the junctions converts the incoming infrared radiation into heat. The output voltage is generated by the Seebeck Effect. An alternate method of producing a pyroelectric material could be to use GaN (gallium nitride) or CsNO3 (cesium nitrate). Even with a very narrow field of detected radiation the Smartec devices are quite large and the most important thing about the new TI part is the astonishingly small size that is achieved.
The TMP006 integrates a MEMS thermopile sensor (no details on the materials used are disclosed), gain for the sensor, a 16-bit delta-sigma ADC, digital control, a local temperature sensor for reference use, and the required voltage references. The quiescent current is just 240 µA with a shutdown current of a typical 0.5 µA – with the serial bus inactive – and 90 µA in shutdown with the serial bus active.
This is a passive sensor in that no infrared source is generated by the part and the typical accuracy of the temperature measurement is ±1ºC (the local temperature reference sensor offers a ±0.5ºC accuracy and the thermal path runs through the solder balls of the package). Communications are with a pin-programmable I2C/SMBus typically operated at 400 kHz. The supply voltage can be as low as 2.2 V for correct operation (7 V maximum).
The sensor offers an output voltage range specified from -40ºC (maximum range down to -55ºC) to +125ºC and gives a 7 µV/ºC output over a range such as +40ºC to +60ºC. The sensor resolution is 156.25 nV. The field of view of the sensor (built-in to the package window on the top) is ±45º to a 50% responsivity. Temperature measurements are held in registers together with configuration information and sensor voltage measurements.
The use of the TMP006 in the size that is available shifts the ability to measure temperatures from an external sensor near to the case, for example, that is of concern to one that can ‘look’ directly at the hot spot of interest. This changes measurement accuracies dramatically and avoids other environmental issues that may add further to inaccuracy. There is no reason to suppose that a version of the device cannot be offered as the basis for a passive motion detector as well. The TMP006 will find a large range of applications for CPU, motor, and power management temperature sensing, as well as for comfort measurements for users. There is also going to be large market in gas detectors such as CO2 sensors There are also likely to be applications that simply cannot be thought of at this time. The size of the package is at least 90% smaller than anything that has gone before and we would expect this first sensor product to be a forerunner for many more in an ambitious and profitable family.
The TMP006 is in production in an 8-ball 1.6mm x 1.6mm WCSP priced at $1.50 in 1000-piece lots. An evaluation module and an IBIS model are available.