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Número de pieza | CAV414 | |
Descripción | Converter IC | |
Fabricantes | Analog Microelectronics | |
Logotipo | ||
Hay una vista previa y un enlace de descarga de CAV414 (archivo pdf) en la parte inferior de esta página. Total 6 Páginas | ||
No Preview Available ! Converter IC for Capacitive Signals CAV414
FEATURES
• Wide Supply Voltage Range: 6...35V
• Wide Operating Temperature Range:
–40°C...+85°C
• High Detection Sensitivity of Relative
Capacitive Changes: 5% – 100%
• Detection Frequency up to 2kHz
• Adjustable Voltage Range:
0...5/10V, other
• Reference Voltage Source: 5V
• Protection against Reverse Polarity
• Output Current Limitation
• Adjustable with only two Resistors
APPLICATIONS
• Industrial Process Control
• Distance Measurement
• Pressure Measurement
• Humidity Measurement
• Level Control
BLOCK DIAGRAM
GENERAL DESCRIPTION
The CAV414 is an universal multipurpose in-
terface for capacitive sensors and contains the
complete signal processing unit on chip. The
CAV414 detects the relative capacitive change
of a measuring capacity to a fixed reference
capacity. The IC is optimised for capacities in
the wide range of 10pF to 2nF with possible
changes of capacity of 5% to 100% of the ref-
erence capacity.
The voltage output is formed by a high accu-
racy instrumentation amplifier in combination
with an operational amplifier.
With only a few external components, the
CAV414 is suitable for a great variety of ap-
plications including a zero compensation.
DELIVERY
• DIL16 packages (samples)
• SO16(n) packages
• Dice on 5“ blue foil
www.DataSheeCt4UO.cSoCm
12
CX1
16
CX2
14
Reference
Oscillator
Integrator 1
Integrator 2
Signal Conditioning
CAV414 VCC
9
IA VOUT
OP 8
GAIN
7
Voltage/Current
Reference
GND
10
VREF
11
Figure 1
15
CL1
13 4 5 6
2
3
1
CL2 RL LPOUT VM RCX1 RCX2 RCOSC
analog microelectronics
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Internet: http://www.analogmicro.de
Phone: +49 (0)6131/91 073 – 0
Fax: +49 (0)6131/91 073 – 30
E–Mail: info@analogmicro.de
January 2001
1/6
Rev. 2.1
1 page Converter IC for Capacitive Signals CAV414
FUNCTIONAL DESCRIPTION
A reference oscillator with a frequency adjusted by the capacity COSC drives two symmetrically built
integrators synchronously to its clock and its phase. The capacitors CX1 and CX2 determine the am-
plitude of the two driven integrators. The difference of the integrator amplitudes gives the relative
change of the capacities CX1 and CX2 to each other with high common mode rejection and high
resolution. The difference signal is conditioned by a lowpass filter. The corner frequency and gain
of it can be adjusted with a few external components. The output of the lowpass filter is connected
to an instrumentation amplifier and an output stage. These two stages transform the signal into an
adjustable voltage.
Adjustment:
The zero-adjustment is made by the resistors RCX1 or RCX2 for the case that the varying capacitance
CX2 has nearly the same (and its smallest) value as the fixed capacitance CX1 (reference capacitance).
Therefore one of this resistors is varied until the differential voltage
VDIFF = VLPOUT −VM
is zero:
VDIFF = 0
Application Example:
The following values are given:
• fixed capacitance CX1:
• varying capacitance CX2:
50pF
50 ... 100pF
www.DaCtaSahlceeut4laUt.cioomn:
With the equations given in the boundary conditions, the following values for the devices can be
calculated:
• COSC: 80pF
• CL1:
10nF
• CL2:
10nF
If the signal VDIFF is amplified, it has to fulfil the unequation:
VDIFF ≤ 400mV
Detailed calculations are shown in a separately available Application Note.
analog microelectronics
January 2001
5/6
5 Page |
Páginas | Total 6 Páginas | |
PDF Descargar | [ Datasheet CAV414.PDF ] |
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