Datasheet AS1716 Capacitive Sensor Interface 1 General Description 2 Key Features Differential input stage with wide input range AS1716 is an analog front end specifically designed for unbiased Capacitive Sensors, as for instance Knock Sensors in Automotive, to Resistive sensor biasing (VDDA/2) be interfaced with Analog Digital Converters with Sample and Hold Programmable Gain (x0.5, x1, x2, x4) input stages. nd Internal 2 order low pass Multiple Feedback Filter with a min. The device provides differential inputs, a 1st order low pass filter to cut off frequency of 16kHz cutoff the high frequency noise components, differential to single ended conversion, programmable gain stage and a 2 pole low pass Single supply operation: 4.5V to 5.5V Multiple Feedback Filter. Operating Temperature range: -40C to +125C The Knock Sensor is a Piezo Electric device that generates a voltage High CMRR: 55dB (min) if it is stressed. It senses knock and transmits information to the elec- tronic engine management control unit. This influences process con- EMC characterized by IEC 61967-4 trol in the engine, for example timing and fuel injection until knock is (1 / 150 Method) eliminated. EMC characterized by IEC 62132-4 The capacitive sensor is biased via resistors to a voltage level of (Direct Power Injection) VDDA/2. Automotive qualified to AECQ100 for IC and PPAP level 3 8-pin SOIC Package 3 Applications Analog front end for Capacitive Sensors to Analog to Digital Convert- ers and DSP. Figure 1. AS1716 - Block Diagram VDDA VSSA NC - INN + VDDA VDDA/2 - Gain Control x0.5, x1, x2, x4 - + + OUT + - VDDA/2 VDDA/2 Multiple Feedback LP Filter fc ~23kHz typ. - INP VDDA/2 + AS1716 VDDA/2 GA GB www.austriamicrosystems.com/Capacitive-Sensors/AS1716 Revision 1.02 1 - 12AS1716 Datasheet - Pinout 4 Pinout Pin Assignment Figure 2. Pin Assignments (Top View) VDDA 1 OUT 8 GA 2 VSSA 7 AS1716 GB 3 NC 6 INP 4 5 INN Pin Description Table 1. Pin Description Pin Name Pin Number Description VDDA 1 Positive Supply GA 2 Gain selection. Internal pull-down of 100k GB 3 Gain selection. Internal pull-down of 100k INP 4 Non-Inverting Input INN 5 Inverting Input NC 6 Not Connected. Must be left unconnected in the application VSSA 7 Negative Supply OUT 8 Signal Output www.austriamicrosystems.com/Capacitive-Sensors/AS1716 Revision 1.02 2 - 12