AS1716_V2 Datasheet, PDF (1/12 Pages) ams AG – Capacitive Sensor Interface

Datasheet
AS1716
Capacitive Sensor Interface
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
VDDA/2.
2 Key Features
Differential input stage with wide input range
Resistive sensor biasing (VDDA/2)
Programmable Gain (x0.5, x1, x2, x4)
Internal 2^nd order low pass Multiple Feedback Filter with a min.
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
(1Ω / 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
Figure 1. AS1716 - Block Diagram
3 Applications
Analog front end for Capacitive Sensors to Analog to Digital Convert-
ers and DSP.
VDDA VSSA NC
INN
VDDA
+
-
-
+
VDDA/2
VDDA/2
INP
AS1716
-
+
VDDA/2
Gain Control
-
x0.5, x1, x2, x4
+
-
+
VDDA/2
Multiple Feedback LP Filter
fc ~23kHz typ.
VDDA/2
OUT
GA GB
www.austriamicrosystems.com/Capacitive-Sensors/AS1716
Revision 1.02
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