AS1716

Capacitive Sensor Interface

www.austriamicrosystems.com/Capacitive-Sensors/AS1716

Revision 1.02

1 - 12

Data sheet

1 General Description

AS1716 is an analog front end specifically designed for unbiased

Capacitive Sensors, as for instance Knock Sensors in Automotive, to

be interfaced with Analog Digital Converters with Sample and Hold

input stages.

The device provides differential inputs, a 1st order low pass filter to

cutoff the high frequency noise components, differential to single

ended conversion, programmable gain stage and a 2 pole low pass

Multiple Feedback Filter.

The Knock Sensor is a Piezo Electric device that generates a voltage

if it is stressed. It senses knock and transmits information to the elec-

tronic engine management control unit. This influences process con-

trol in the engine, for example timing and fuel injection until knock is

eliminated.

The capacitive sensor is biased via resistors to a voltage level of

Figure 1. AS1716 - Block Diagram

2 Key Features

Differential input stage with wide input range

Programmable Gain (x0.5, x1, x2, x4)

Internal 2

cut off frequency of 16kHz

Single supply operation: 4.5V to 5.5V

Operating Temperature range: -40°C to +125°C

High CMRR: 55dB (min)

EMC characterized by IEC 61967-4

(1

Ω / 150Ω Method)

EMC characterized by IEC 62132-4

(Direct Power Injection)

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.

+

-

-

+

-

+

VDDA

VDDA/2

Multiple Feedback LP Filter

fc ~23kHz typ.

INP

GA

GB

OUT

NC

VSSA

VDDA

Gain Control

x0.5, x1, x2, x4

-

+

VDDA/2

VDDA/2

VDDA/2

-

+

VDDA/2

INN

AS1716