MEMS device radically reshapes IR non-contact temperature sensing for consumer products

So, you need to measure the temperature of your IC, PCB, or box? No big deal: you can use one of the many available approaches, via sensors such as a thermocouple, RTD, thermistor, diode, or an IC-based sensor, along with the appropriate signal-conditioning circuitry IC if needed.

But what if you want to measure than temperature without physical contact? Then it’s a bigger challenge, since you'll likely go to an infrared (IR) detector (usually a thermopile) plus its specialized conditioning channel. It's relatively large, power-hungry, and costly.

Or maybe you should say, "it was a bigger challenge." Texas Instruments claims their TMP006 is the world's first single-chip, passive IR temperature sensor, complete with on-chip MEMS thermopile sensor, signal-conditioning channel, 16-bit analog/digital converter, local temperature and voltage references, and digital interface—all in a 1.6 × 1.6 mm monolithic chip.

Applications include portable and consumer electronic devices, such as handsets, tablets, gas detectors, and other temperature-sensing situations—and temperature is the most widely sensed physical parameter.TI says this device is 95% smaller than competitive devices, and just 240 μA in quiescent mode and 1 μA in shutdown mode, 90% less power than available devices. It offers both I²C and SMBus digital interfaces.

Of course, when talking temperature sensing, it's also about range and accuracy. The TMP006 operates from -40 to +125⁰C, with typical accuracy of ±1⁰C for the passive IR sensor and ±0.5⁰C for the local temperature sensor.

IR sensing offers advantages even in close-in, non-remote sensing situations. For example, if your PCB circuitry needs to sense the temperature of the case, you could place a sensor on the hottest location, but this is often impractical, difficult in assembly, and hard to work with. Or, you can place the sensor near the CPU, or rely on the CPU's internal sensor, and approximate the case temperature based on the presumed correlation (linkage) between the sensor and the case.

Using an IR sensor, however, you can place the sensor directly on the PCB, just like any IC, and read the case's passive IR energy. This is much easier in terms of physical layout and assembly, and also takes into account the external temperature the case is "feeling".

Price, packaging, and availability: The TMP006 is housed in a 1.6 x 1.6 mm WCSP, priced at $1.50 (1000 units); it is available now.

Support and more information: An evaluation module is available for $50. Also available is an IBIS model to assess and verify board signal-integrity requirements, along with source code for calculating object temperature. Data sheets are posted at http://www.ti.com/tmp006ds-pr and a demo video is at http://www.ti.com/tmp006v-pr .