Housed in a tiny 8-pin package, the STM8T141 touch-sensor controller from STMicroelectronics can improve the performance and styling of products, such as mobile phones, portable consumer products, and appliances. The IC allows the replacement of conventional buttons with a touch sensor for main power-on/off or to trigger wake-up from battery-saving sleep modes.
The STM8T141 draws a current as low as 11 µA from the battery and can detect user presence via the touch-sensor electrode, responding quickly to wake the system from a low-power sleep mode. It monitors a single touch-sensing electrode embedded on the control panel of an end-product or in the outer casing. The sensor can be hidden, or its position indicated using a printed, overlaid, or illuminated icon.
The device also supports proximity sensing, allowing equipment to be controlled without direct contact from the user. This allows the sensor to control power-saving features, such a system wake-up on user detection, or features for added convenience, like automatic backlight activation supporting find-in-the-dark capability.
Other features include self-calibration, automatic recalibration, and environmental compensation filtering. The chip supports a driven electrode-shielding wire, which protects against noise from external sources without the reduction in electrode sensitivity experienced with a grounded shield.
A number of development tools are available for the touch-sensor IC. An evaluation kit demonstrates the chip’s touch and proximity features, while the ST-TSLINK programming dongle and STM8T14X-SB socket programming board are used with the STVP PC-based programming tools for product configuration.
The STM8T141 is sampling to lead customers in the 3x2x0.6-mm ultra-small and low-profile DFN8 package and is now in volume production. High volumes are available immediately in a narrow variant of the SO-8 package, priced at $0.45 in quantities of 10,000.