IC FOR PROXIMITY DETECTOR

AM 313

analog microelectronics

April 2005

3/4

ABSOLUTE MAXIMUM RATINGS

35V

32V

20mA

150°C

– 55...125°C

FUNCTIONAL DESCRIPTION

The proximity detection is based on the amplitude attenuation of an LC–oscillator which depends

on the distance to a metal object.

The signal from the oscillator is rectified and filtered, then detected by a Schmitt–Trigger which

An additional LED output shows the on-state of the detection. The LED is blanked in the case of

short circuit. To protect the circuit from overload, the outputs are disconnected and retested

The temperature compensation to adapt the oscillator voltage to different types of external LC

resonators is performed by connecting a resistor between pins 7 (VREF) and 2 (RK).

The circuit has a power–on–delay which is adjusted with CABT. Within this delay, the outputs Q

FUNCTIONAL DIAGRAMS

AM313

1

2

3

4

5

6

7

8

9

10

11

14

15

16

VREF

VCC

LED

R

m

Z

2

Q

Q

T

Z

1

D

2

C

R

D

1

V

CC

Output

Ground

R

S

R

D

R

H

R

K

C

OSC

L

Figure 2