CAV414 AME | Alldatasheet

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Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 Analog Microelectronics GmbH Phone: +49 (0)6131/91 073 – 0 1/6 An der Fahrt 13, D – 55124 Mainz Fax: +49 (0)6131/91 073 – 30 Rev. 2.1 Internet: http://www. analogmicro.de E–Mail: info@analogmicro .de

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 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 BLOCK DIAGRAM CA V414 Integrator 1 Integrator 2 V oltage/Current Reference IA 15 13 4 5 6 3 1 VCC GAIN OP 8 VOUT GND VREF RCOSCRCX2RCX1VMLPOUTRLCL2CL1 CX2 CX1 COSC Reference Oscillator Signal Conditioning Figure 1

Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 ELECTRICAL SPECIFICATIONS Tamb = 25°C, VCC = 24V, IREF = 1mA (unless otherwise noted) Parameter Symbol Conditions Min. Typ. Max. Unit Supply Supply Voltage VCC 63 5 V Temperature Specifications Operating Tamb –40 85 °C Storage Tst –55 125 °C Junction Tj 150 °C Thermal Resistance Θja DIL16 plastic package 70 °C/W Θja SO16 (n) plastic package 140 °C/W Reference Oscillator Oscillator Capacitor Range COSC COSC = 1.6 ⋅ CX1 14 1800 pF Oscillator Frequency Range fOSC 1 130 kHz Oscillator Current IOSC ROSC = 200kΩ 9.5 10 10.75 µA Capacitive Integrator 1 and 2 Capacitor Range 1 CX1 10 1000 pF Capacitive Integrator Current 1 IX1 RCX1 = 400kΩ 4.75 5 5.38 µA Capacitor Detection Sensitivity ∆ CX ∆ CX = (CX2 − CX1 )/CX1 5 100 % Capacitor Range 2 CX2 CX2 = CX1 ⋅ (1 + ∆ CX ) 10.5 2000 pF Capacitive Integrator Current 2 IX2 RCX2 = 400kΩ 4.75 5 5.38 µA Detection Frequency fDET CL1 = CL2 =1nF 2 kHz Lowpass Adjustable Gain GLP 11 0 Output Voltage VLPOUT VM –0.4 VM +0.4 V Corner Frequency 1 fC1 R01 = 20kΩ, CL1 =1nF 10 kHz Corner Frequency 2 fC2 R02 = 20kΩ, CL2 =1nF 10 kHz Resistive Load at PIN LPOUT R LOAD 200 kΩ Capacitive Load at PIN LPOUT C LOAD 50 pF Temperature Coefficient VDIFF (together with Input Stages) dVDIFF /dTV DIFF = VLPOUT - VM , Tamb = –40 ... 85°C ±100 ppm/°C Internal Resistor 1 and 2 R01, R02 20 kΩ Temperature Coefficient R01,02 dR01,02 /dTT amb = –40 ... 85°C 1.9 10 -3/°C Power Supply Rejection Ratio (together with Input Stages) PSRR IOUT ≤ 1mA 80 90 dB Voltage Reference VREF Voltage VREF 4.75 5 5.25 V Current IREF 09 m A VREF vs. Temperature d VREF /dTT amb = –40...+85°C ±90 ±140 ppm/°C Line Regulation d VREF /dVV c c = 6V...35V 30 80 ppm/V dVREF / dV Vcc = 6V...35V, IREF ≈ 4mA 60 150 ppm/V Load Regulation d VREF /dI 0.05 0.10 %/mA dVREF /dI IREF ≈ 4mA 0.06 0.15 %/mA Load Capacitance CREF 1.9 2.2 5.0 µF

Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 Parameter Symbol Conditions Min. Typ. Max. Unit Voltage Reference VM Voltage VM 1.90 2 2.15 V VM vs. Temperature d VM /dTT amb = –40...+85°C ±90 ppm/°C Current IVM Source 5 µA IVM Sink -5 µA Load Capacitance CVM 80 100 120 nF Instrumentation Amplifier Input Stage Internal Gain GIA 4.9 5 5.1 Differential Range VIN 0 400 mV Common Mode Input Range CMIR V CC < 9V, ICV < 2mA 1.5 VCC - 3 V CMIR VCC ≥ 9V, ICV < 2mA 1.5 6.0 V Common Mode Rejection Ratio CMRR 80 90 dB Power Supply Rejection Ratio PSRR IOUT ≤ 1mA 80 90 dB Offset Voltage VOS ±1.5 ±6m V VOS vs. Temperature d VOS /dT ±5 µV/°C Output Stage Adjustable Gain GOP 1 Input Range IR V CC < 11V 0 VCC - 5 V IR VCC ≥ 11V 06 V Power Supply Rejection Ratio PSRR IOUT ≤ 1mA 80 90 dB Offset Voltage VOS ±0.5 ±2m V VOS vs. Temperature d VOS /dT ±3 ±7 µV/°C Input Bias Current IB 10 25 nA IB vs. Temperature d IB /dT 72 0 p A / ° C Output Voltage Range VOUT VCC < 19V 0 VCC - 5 V VOUT VCC ≥ 19V 01 4 V Output Current Limitation ILIM VCC ≥ 10V 57 1 0 m A Output Current IOUT 0 ILIM mA Load Resistance RL 2 kΩ Load Capacitance CL 500 nF Protection Functions Protection Against Reverse Polarity Ground vs. VCC vs. VOUT 35 V Note: 1) The oscillator capacity has to be chosen in the following way: COSC = 1.6 ⋅ CX1 2) The capacitor range of CX1 and CX2 can be extended whereby the system performance is reduced and the electrical limits are exceeded. 3) Currents flowing into the IC, are negative.

Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 BOUNDARY CONDITIONS Parameter Symbol Min. Typ. Max. Unit Current Definition of Ref. Oscillator RCOSC 190 200 210 kΩ Current Adjustment of Cap. Integrator 1 RCX1 350 400 450 kΩ Current Adjustment of Cap. Integrator 2 RCX2 350 400 450 kΩ Lowpass Stage Resistor Sum RL1 + RL2 90 200 kΩ Output Stage Resistor Sum R1 + R2 90 200 kΩ Reference Voltage 5V CREF 1.9 2.2 5 µF Reference Voltage 2V (only for internal use) CVM 80 100 120 nF Lowpass Capacitance 1 CL1 100⋅CX1 200⋅CX1 Lowpass Capacitance 2 CL2 100⋅CX1 200⋅CX1 Oscillator Capacitance COSC COSC =1.55⋅CX1 COSC =1.60⋅CX1 COSC =1.65⋅CX1 Note: The system performance over temperature forces that the resistors RCX1, RCX2 and ROSC have the same temperature coefficient and a very close placement of them in the circuit. The capacities CX1, CX2 and COSC are also forced to have the same temperature coefficient and a very close placement of them in the circuit. FUNCTIONAL DIAGRAM CA V414Reference Oscillator Integrator 1 Integrator 2 OP Signal Conditioning V oltage/Current Reference IA 15 13 4 5 6 3 1 VCC OUT GND ROSCRCX2RCX1CL1 CL2 CVMRL1 RL2 COSC CX1 CX2 VLPOUT VM VDIFF VCX1 VCX2 VCX,DIFF R01 R02 CREF Figure 2

Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 FUNCTIONAL DESCRIPTION A reference oscillator with a frequency adjusted by the capacity COSC drives two symmetrically built integrators synchronously to its cl ock 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 C X1 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 compone nts. 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 R CX1 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 MLPOUTDIFF VVV −= is zero: 0=DIFFV Application Example: The following values are given:

  • fixed capacitance CX1: 50pF
  • varying capacitance CX2: 50 ... 100pF Calculation: 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.

Converter IC for Capacitive Signals CAV414 analog microelectronics January 2001 PINOUT CX1 CL1 CX2 CL2 COSC VREF VCC GND RCOSC RCX1 RCX2 RL LPOUT VM GAIN VOUT 8 9 Figure 3 DELIVERY The CAV414 is available in version:

  • 16–Pin–DIL (samples)
  • SO 16 (n) (Maximum Power Dissipation PD = 300mW)
  • Dice on 5“ blue foil PACKAGE DIMENSIONS SO16 (n) PIN NAME DESIGNATION 1 RCOSC Current Definition of Ref. Oscillator 2 RCX1 Current Adjustment of Cap. Integrator 1 3 RCX2 Current Adjustment of Cap. Integrator 2

4 RL Gain Adjustment of Lowpass Filter

5 LPOUT Output of Lowpass Filter

6 VM Reference Voltage 2V

7 GAIN Gain Adjustment

8 VOUT Voltage Output

9 VCC Supply Voltage

10 GND IC Ground

11 VREF Reference Voltage 5V

12 COSC Capacitor of Reference Oscillator

13 CL2 Corner Frequency of Lowpass 2

14 CX2 Integrator Capacitor 2

15 CL1 Corner Frequency of Lowpass 1

16 CX1 Integrator Capacitor 1

The information provided herein is believed to be reliable; however, Analog Microelectronics assumes no responsibility for inaccuracies or omissions. Analog Microelectronics assumes no responsibility for the use of this information, and all use of such information shall be entirely at the user's own risk. Prices and specifications are subject to change without notice. No patent rights or licences to any of the circuits described herein are implied or granted to any third party. Analog Microelectronics does not authorise or warrant any Analog Microelectronics product use in life support devices and/or sys- tems. 4,0 + 0,2 - 0,1 0,2 ± 0,05 1,27 ≤ 2,00 10,06 ± 0,1 1,45 ± 0,1 0,2 ± 0,1 Figure 4