TSOP18..RF1

Vishay Telefunken

3 (7)

Rev. 4, 24-Jan-00

www.vishay.de

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Document Number 82050

Suitable Data Format

The circuit of the TSOP18..RF1 is designed in that way

that unexpected output pulses due to noise or

disturbance signals are avoided. A bandpassfilter, an

integrator stage and an automatic gain control are

used to suppress such disturbances.

The distinguishing mark between data signal ( not

suppressed) and disturbance signal (supressed) are

carrier frequency, burst length and Signal Gap Time

(see diagram below).

The data signal should fullfill the following condition:

• Carrier frequency should be close to center fre-

quency of the bandpass (e.g. 38kHz).

• Burst length should be 6 cycles/burst or longer.

• After each burst a gap time of at least 9 cycles is

neccessary.

• The data format should not make a continuous

signal transmission. There must be a Signal Gap Time

(longer than 15ms) at least each 90ms (see Figure A)

Some examples for suitable data format are:

NEC Code (repetitive pulse), NEC Code (repetitive

data), Toshiba Micom Format, Sharp Code, RC5

Code, RECS–80 Code, R–2000 Code.

When a disturbance signal is applied to the

TSOP18..RF1

it can still receive the data signal.

However the sensitivity is reduced to that level that no

unexpected pulses will occure.

Some examples for such disturbance signals which

are suppressed by the TSOP18..RF1 are:

• DC light (e.g. from tungsten bulb or sunlight),

• Continuous signal at 38kHz or at any other

frequency,

• Signals from fluorescent lamps ( see Figure B ).

• Continuous IR signal (e.g. 1ms burst, 2ms pause)

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1020

3040506070

8090

100

time [ms]

Signal Gap Time

Figure A: Data Signal (Output of IR Receiver) with a Signal Gap Time of 20ms

0

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20

time [ms]

Signal Gap Time