STM8T141AU61T STMicroelectronics

STM8T141 Single-channel capacitive sensor for touch or proximity detection with shielded sensing electrode Features Touch or proximity detection (a few centimeters) Built-in driven shield function: Enhance proximity detection Protect sensing electrode from noise interference SO8 UFDFPN8 (narrow) (2 x 3 mm) Ultra-low power modes suitable for battery applications (11 A in extreme low power mode) On-chip integrated voltage regulator Table 1. Device summary Environment compensation filter Feature STM8T141 User programmable options include: Four detection thresholds Operating supply voltage 2.0 V to 5.5 V Four output modes Supported interface Single key state output Four low power modes Operating temperature 40 to +85 C Reference freeze timeout 8-pin SO Packages Minimal external components 8-pin UFDFPN Applications Consumer electronics Power-critical and battery applications Wake-up on proximity Home and office appliances Find-in-the-dark (FITD) applications using proximity detection Sanitary ware and white goods Flameproof human interface devices for use in hazardous environments June 2011 Doc ID 15699 Rev 7 1/50 www.st.com 1 Contents STM8T141 Contents 1 Description . 7 2 Block diagram 8 3 Pin descriptions 9 4 STM8T ProxSense technology 10 4.1 Capacitive sensing overview 10 4.2 Charge transfer acquisition principle 10 5 STM8T processing . 12 5.1 Signal and reference calculation . 12 5.2 Determining touch/proximity . 12 5.3 Environment compensation filter (ECF) 13 5.3.1 ECF principle . 13 5.3.2 Reference freeze timeout 15 5.3.3 Debounce filter 16 6 Typical application diagram 17 7 Device operation . 18 7.1 Option byte description . 18 7.2 TOUT/POUT output mode 20 7.2.1 Active . 20 7.2.2 Toggle 21 7.2.3 3-second latch 21 7.2.4 30-second latch . 22 7.3 Detection threshold . 22 7.4 Power modes 23 7.4.1 Normal Power mode . 23 7.4.2 Low Power mode with Zoom . 24 7.4.3 Extreme Low Power mode with Zoom 24 7.4.4 Extreme Low Power mode . 25 7.5 Charge transfer frequency 25 2/50 Doc ID 15699 Rev 7