CAV424 Datasheet, PDF (7/16 Pages) List of Unclassifed Manufacturers – Converter IC for Capacitive Signals

CAV424 - C/U transducer IC
with adjustable output voltage
CAV424
COSC
12
Reference-
oszillator
VTEMP
7
T Sensor
RCR RCM
2
3
RCOSC
1
VCC
11
Current reference
6 _VM
CR
16
CM₁₄
Integrator 1
Integrator 2
Signal conditioning
5
LPOUT
10
GND
15
CL1
13 4
CL2
RL
Figure 5: Block diagram and signal pattern
Signal conditioning
The filtered and smoothed voltage has a value of V_TPAS:
& ' V_TPAS
"
3_#
8
V_CR
( V_CM
(7)
Signal V_TPAS can be boosted using the follow-on internal operational amplifier, with the
amplification G_LP being determined by resistors R_L1 and R_L2. G_LP is calculated as:
G_LP
" 1%
R_L1
R_L2
(8)
With (7), this results in:
& ' V_DIFF
" G_LP
# V_TPAS
" G_LP
#³#
8
V_CR
( V_CM
For the output signal reference to ground (GND) it thus follows that:
V_LPOUT " V_DIFF % V_M
(9)
V_LPOUT = f(C_M, (C_R), f_osc, I_CM, I_CR), where the basic values of C_M and C_R must be placed in a fixed
ratio. f_osc or I_CM, I_CR act as parameters.
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
Phone: [phone]
Fax: [phone]
Internet:
http://www.analogmicro.de
Email: [e-mail]
July 2007 - Rev 1.2 - Page 7/16