CAV444 Datasheet, PDF (10/12 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
Parameter
Temperature Sensor V_TEMP
Voltage
Sensitivity
Thermal Nonlinearity
Symbol
Conditions
Min.
V_TEMP
dV_TEMP/dT
R_TEMP ≥ 50M
R_TEMP ≥ 50M
R_TEMP ≥ 50M , end point method
2.20
Typ.
2.32
8
0.5
Max.
Unit
2.45
V
mV/°C
% FS
Table 1: Electrical specifications for CAV444
Notes:
1) Currents flowing into the IC are negative.
2) R_TEMP is the minimum possible load resistance at pin VTEMP.
In order to achieve as good a temperature behavior as possible, it is essential that resistors R_CM and R_CW have the same
temperature coefficients and that they are placed very close together in the circuit.
STANDARD DIMENSIONING
Parameter
Symbol
Min.
Typ.
Max.
Unit
Output Stage Resistors (1%)
R₂ , R₄ , R₅
100
kΩ
Full-Scale Resistor (0.1%), Calibration Start Value*
R₁
33
kΩ
Offset Resistor (0.1%), Calibration Start Value*
R₃
100
kΩ
f/V-Stage Biasing Resistor
R_A
240
kΩ
Measurement Oscillator Resistor
R_CM
250
kΩ
f/V-Stage Filter Resistor
R_CW
500
kΩ
Filter Capacitors (vary with value of C_M,min)**
C_F1 ,C_F2
3.8
440
nF
Reference Voltage Capacitor (V_REF = 2.5V)
C_VREF
80
100
120
nF
Table 2: Standard values for external components
• *) R₁ and R₃ are the initial values given at the start of the calibration process (Kali_CAV444.xls). During
calibration, these are replaced by precisely computed, individual values.
• **) C_F1 and C_F2 are dimensioned by the calibration program.
BOUNDARY CONDITIONS
Parameter
Maximum Supply Voltage
Oscillator Frequency Range
f/V Converter Current
Measurement Oscillator Current
Symbol
V_CCmax
f_OSC
I_CW
I_CM
Condition
R_CW = 500 kΩ
R_CM = 250 kΩ
Min.
1
Typ.
Max.
Unit
17
V
130
kHz
5.38
µA
10.75
µA
Table 3: Boundary conditions
Analog Microelectronics GmbH
An der Fahrt 13, D – 55124 Mainz
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Internet: http://www.analogmicro.de
Email: [e-mail]
Mai 2010 - Rev 1.1 - Page 10/12