CAV444 Datasheet, PDF (3/12 Pages) Analog Devices – C/V transmitter IC with adjustable output voltage for capacitive input signals

CAV444 – C/V transmitter IC
with adjustable output voltage
for capacitive input signals
FEATURES
GENERAL DESCRIPTION
• Differential output signal
• Wide capacitor measuring range:
18 pF to 2.2 nF
• Linear transfer behavior
• Adjustable offset voltage
• Adjustable full-scale signal
• Detection frequency: 15 Hz to 1.9 kHz
• Measurement oscillator frequency:
1 kHz to 130 kHz
• Wide dynamic range detection
• Wide temperature range:
-40°C...+85°C
• Simple calibration (Excel program)
• RoHS compliant
CAV444 is an integrated C/V transducer that
contains full signal conditioning electronics for
the linear conversion of capacitive input sig-
nals into a suitable differential output voltage.
It also has an additional temperature detector.
The output signal is proportional to the change
in capacitance ∆C_M = C_M,_max – C_M,_min.
A differential voltage referenced to internal
reference voltage V_REF is generated as an
output signal. This output voltage has been
specially designed for connection to a following
A/D converter.
As this is an analog circuit, its resolution are
only limited by noise.
BLOCK DIAGRAM
Together with the integrated temperature
sensor of the CAV444 and a processor,
electronically calibratable systems can be
assembled.
A simple Excel software program eases the
dimensioning of CAV444.
.
VTEMP
7
GND
10
RA VCC VB
14
11
3
Temperature-
Sensor
CAV444
Supply
6 VREF
CM ¹² _Measurement
f/V
RCM ₁ ^{oszillator converter}
Lowpass
filter
16 2
CW RCW
15 13
CF1 CF2
Figure 1: Block diagram of CAV444
Output
stage
5 VOUT
4
GAIN
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Phone: [phone]
Fax: [phone]
Internet: http://www.analogmicro.de
Email: [e-mail]
Mai 2010 - Rev 1.1 - Page 3/12