New ams TMD2635 Proximity Sensor Module Enhances Smaller True Wireless Earbud Designs

September 17 2019, 06:10
Austrian sensor specialist ams announced the world’s smallest 2-in-1 IR proximity sensor module, paving the way to smaller, lighter, and always-available True Wireless Stereo (TWS) earbuds. The ultra-small package of the new ams TMD2635 module measures just 1mm3 and enables ear detection triggers for wireless earbud in-and-out movements, helping to extend battery life between charges. Two TMD2635 modules can be used in tandem to enable touchless gesture controls.

Consumer audio wireless headset use continues to grow as users further immerse themselves in their modern lifestyles. According to market research conducted by SAR Insight & Consulting, the earbud market is projected to enjoy a compound annual growth of 27% in the years to 2023, by which time true wireless earbuds are expected to overtake all other wireless and wired product categories to become the most popular type of headphone worldwide.

The new ams TMD2635 is a complete light-to-digital sensor module which integrates a low power infrared VCSEL (Vertical Cavity Surface Emitting Laser) emitter, near- and far-field proximity circuitry, and a digital fast-mode I2C interface, all in a miniature land grid array (LGA) package. 

By incorporating TMD2635 modules in new TWS earbud designs, wearable device manufacturers can appeal to consumers’ desire for smaller, more comfortable products, that are able to sustain prolonged operational use, reliably detecting when earbuds are inserted or removed from the ear.

“The TMD2635 underpins ams’ leading proximity sensing position in the consumer electronics market. This latest product occupies 1mm3 of space and is more than six times smaller by volume than the previous 2-in-1 IR proximity sensor module. And because of the split near-far field photodiode offset emitter to detector positioning, designers of wireless earbuds and other wearable and portable devices have the freedom to optimize both the size and shape of the needed sensor apertures in their industrial designs and optimize their products for comfort and performance – either a 1.5mm circular or a 1x2mm oval aperture,” explains Dave Moon, Senior Product Marketing Manager in the Integrated Optical Sensors business line at ams.

From smartphones to wearables
The TMD2635 module power-saving benefits are paramount especially in the small battery capacity and size of true wireless earbud designs. The module has an average active-mode current consumption of 70µA and 0.7µA in Sleep mode. 

The development of the TMD2635 infrared sensor module benefited from ams’ long heritage in optical sensor development and production. ams is a long-time market share leader in proximity, ambient light and color sensors and sensor modules for mobile phones. The company's intellectual property, covers technologies and production methods for miniature optical emitters, photodetectors and spectral sensors.

The design of the TMD2635’s optical stack and the high performance of its internal laser emitter result in outstanding crosstalk rejection, high immunity to interference from ambient light, and support for highly effective algorithms which convert infrared light measurements to improve the accuracy of proximity detection results. According to ams, the proximity detection performance of the TMD2635 is comparable to that of earlier, larger modules used by the leading smartphone manufacturers, but in a significantly reduced form-factor appropriate for the small design spaces available in wearable devices.

The TMD2635 is available now in production volumes with unit prices at $0.89 for quantities of 1,000 units. Sample and more technical information ara available on request. Visit:
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