Converter IC for Capacitive Signals

CAV414

analog microelectronics

January 2001

4/6

BOUNDARY CONDITIONS

Parameter

Symbol

Min.

Typ.

Max.

Unit

Current Definition of Ref. Oscillator

190

200

210

k

Ω

Current Adjustment of Cap. Integrator 1

350

400

450

k

Ω

Current Adjustment of Cap. Integrator 2

350

400

450

k

Ω

Lowpass Stage Resistor Sum

90

200

k

Ω

Output Stage Resistor Sum

90

200

k

Ω

Reference Voltage 5V

1.9

2.2

5

µF

Reference Voltage 2V (only for internal use)

80

100

120

nF

Lowpass Capacitance 1

100

⋅C

X1

200

⋅C

X1

Lowpass Capacitance 2

100

⋅C

X1

200

⋅C

X1

Oscillator Capacitance

have the same temperature coefficient and a very close placement of them in the circuit.

FUNCTIONAL DIAGRAM

CAV414

Reference

Oscillator

Integrator 1

Integrator 2

OP

Signal Conditioning

Voltage/Current

Reference

IA

12

16

14

15

13

4

5

6

3

1

7

8

9

10

VCC

OUT

GND

R

1

R

2

2

R

OSC

R

CX2

R

CX1

C

L1

C

L2

C

VM

R

L1

R

L2

C

OSC

C

X1

C

X2

V

LPOUT

V

M

V

DIFF

V

CX1

V

CX2

V

CX,DIFF

R

01

R

02

C

REF

11

Figure 2