1

Features

OSC

Feedback

GND

23.6k

W

4.8k

W

300

mA

OSC

RF

TANK

DEMOD

Neg Transient

Suppression

Oscillator

DEMOD

VBE/R Current

Regulator

COMP

+

-

DVBE/R Current

Regulator

s

Separate Current

Regulator for Oscillator

s

Negative Transient

Suppression

s

Variable Low-Level

Feedback

s

Improved Performance

over Temperature

s

6mA Supply Current

Consumption at

s

Output Current Sink

Capability

Package Options

8L PDIP & SO

14L SO

Proximity Detector

7

8

1

2

3

4

5

6

OSC

TANK

Gnd

RF

DEMOD

10

7

14

13

12

8

1

2

3

4

5

6

11

9

OSC

TANK

Gnd

N.C.

N.C.

N.C.

RF

N.C.

DEMOD

N.C.

N.C.

CS209A

Description

The CS209A is a bipolar monolithic

integrated circuit for use in metal detec-

tion/proximity sensing applications.

The IC (see block diagram) contains two

on-chip current regulators, oscillator

and low-level feedback circuitry, peak

detection/demodulation circuit, a com-

parator and two complementary output

stages.

The oscillator, along with an external

LC network, provides controlled oscilla-

tions where amplitude is highly depen-

dent on the Q of the LC tank. During

low Q conditions, a variable low-level

feedback circuit provides drive to main-

tain oscillation. The peak demodulator

senses the negative portion of the oscil-

lator envelop and provides a demodu-

lated waveform as input to the com-

parator. The comparator sets the states

of the complementary outputs by com-

paring the input from the demodulator

to an internal reference. External loads

are required for the output pins.

A transient suppression circuit is

included to absorb negative transients

at the tank circuit terminal.

Block Diagram

Absolute Maximum Ratings

Supply Voltage ................................................................................................24V

Storage Temperature Range ....................................................Ð55¡C to +165¡C

Junction Temperature...............................................................Ð40¡C to +150¡C

Electrostatic Discharge (except TANK pin) ................................................2kV

Lead Temperature Soldering

Wave Solder(through hole styles only) ...........10 sec. max, 260¡C peak

Reflow (SMD styles only) ...........60 sec. max above 183¡C, 230¡C peak

A

Company

¨

Rev. 3/11/99

Cherry Semiconductor Corporation

2000 South County Trail, East Greenwich, RI 02818

Tel: (401)885-3600 Fax: (401)885-5786

Email: info@cherry-semi.com

Web Site: www.cherry-semi.com