CAV424

C/V-converter for single and differential capacitive input signals

July 2014 – Rev. 3.0

Page 4/14

www.analogmicro.de

SPECIFICATIONS

1. Electric Specifications

Tamb = 25°C, VCC = 5V, IOSC = 20µA, ICR = ICM = 2.5µA (unless otherwise noted)

Parameter

Symbol

Conditions

Min.

Typ.

Max.

Unit

System

Operating Temperature

Tamb

-40

105

°C

Supply Voltage

VCC

ratiometric range

4.75

5.00

5.25

V

Current consumption

ICC

Tamb = 25°C, G = 1

1.3

mA

Tamb = -40 .. 105°C, ICR = ICM = 25 µA

1.7

Measurement Capacitance

1), 2)

CM

5

40000

pF

Reference Capacitance Range

2)

CR

5

10000

pF

Output Voltage

3)

VOUT

1.0

4.0

V

Differential Output Voltage

VDIFF

VDIFF = VOUT - VREF

-1.5

1.5

V

Temperature Coefficient VOUT

4)

TCVOUT

dVOUT/(dT·VSPAN) @ Tamb = -40..85°C

±200

ppm/°C

Maximum Input Signal Frequency

5)

fsig,max

@ fOSC = 230 kHz, CF1 = CF2 = 2 nF

3.5

kHz

Minimal Response Time

6)

tRES,min

@ fOSC = 230 kHz, CF1 = CF2 = 2 nF

0.4

ms

Oscillator

Oscillator Capacitor Range

2)

COSC

20

11000

pF

Oscillator Frequency Range

fOSC

fOSC = VREF / (2·∆VOSC·ROSC·COSC)

1

240

kHz

Oscillator Voltage Amplitude

∆

VOSC

2.1

2.15

2.2

V

Oscillator Current Resistor

ROSC

50

125

kΩ

Oscillator Charge Current

IOSC

IOSC = VREF / ROSC

20

50

µA

Charge Current Spread

IOSC,var

@ ROSC = 125kΩ

19

20

21

µA

Reference Integrator (for CR)

Min. Ref. Integrator Voltage

VCR,min

@ Pin 16

1.15

1.2

1.25

V

Max. Ref. Integrator Voltage

VCR,max

@ Pin 16

4.1

V

Ref. Integrator Current Resistor

RCR

100

1250

kΩ

Ref. Integrator Charge Current

ICR

ICR = VREF /RCR

2

25

µA

Charge Current Spread

ICR,var

@RCR = 1000kΩ

2.4

2.5

2.6

µA

Measurement Integrator (for CM)

Min. Meas. Integrator Voltage

VCM,min

@ Pin 14

1.15

1.2

1.25

V

Max. Meas. Integrator Voltage

VCM,max

@ Pin 14

4.1

V

Meas. Integrator Current Resistor

RCM

100

1250

kΩ

Meas. Integrator Charge Current

ICM

ICM = VREF / RCM

2

25

µA

Charge Current Spread

ICM,var

@ RCM = 1000 kΩ

2.4

2.5

2.6

µA

Lowpass Stage

Internal Resistor 1 and 2

R01, R02

20

kΩ

Low Pass Filter Capacitors

7)

CF1, CF2

2

500

nF

Corner Frequency

fC

R01 = R02 = 20kΩ, CF1 = CF2 = 2 nF

4

kHz

LP-Stage Voltage Input

VLP,in

0.8

4.2

V

Offset Voltage

VLP,ofs

between Pin 15 and 13, VLP,in = VREF

-2

2

mV