AD7148

Programmable Touch Controller for Single Electrode Capacitance Sensors AD7148 FEATURES www.datasheet4u.com Programmable capacitance-to-digital converter (CDC) Femtofarad (fF) resolution 8 capacitance sensor inputs 25 ms update rate, all 8 sensor inputs No external RC components required Automatic conversion sequencer On-chip automatic calibration logic Automatic compensation for environmental changes Automatic adaptive threshold and sensitivity levels Register map compatible with AD7143 On-chip RAM to store calibration data I2C-compatible serial interface Separate VDRIVE level for serial interface Interrupt output 16-lead, 4 mm × 4 mm LFCSP 2.6 V to 3.3 V supply voltage Low operating current Full power mode: 1 mA Low power mode: 21.5 μA FUNCTIONAL BLOCK DIAGRAM ACSHIELD VCC 5 8 GND 7 BIAS 6 AD7148 CIN0 13 CIN1 14 CIN2 15 CIN3 16 CIN4 CIN5 CIN6 CIN7 1 2 3 4 EXCITATION SOURCE CALIBRATION RAM 16-BIT Σ-Δ CDC POWER-ON RESET LOGIC SWITCH MATRIX CALIBRATION ENGINE CONTROL AND DATA REGISTERS SERIAL INTERFACE AND CONTROL LOGIC INTERRUPT AND GPIO LOGIC 9 10 11 12 VDRIVE SDA SCLK INT APPLICATIONS Cell phones Personal music and multimedia players Smart handheld devices Television, A/V, and remote controls Gaming consoles Digital still cameras Figure 1. GENERAL DESCRIPTION The AD7148 is designed for use with capacitance sensors implementing functions such as buttons, scroll bars, and wheels. The sensors need only one PCB layer, enabling ultrathin applications. The A...