VISHAY

TSOP12..WI1

Document Number 82022

Rev. 1.7, 27-Jan-05

Vishay Semiconductors

www.vishay.com

5

Suitable Data Format

The circuit of the TSOP12..WI1 is designed in that

way that unexpected output pulses due to noise or

disturbance signals are avoided. A bandpass filter, an

integrator stage and an automatic gain control are

used to suppress such disturbances.

The distinguishing mark between data signal and dis-

turbance signal are carrier frequency, burst length

and duty cycle.

The data signal should fulfill the following conditions:

• Carrier frequency should be close to center fre-

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

• Burst length should be 10 cycles/burst or longer.

• After each burst which is between 10 cycles and 70

cycles a gap time of at least 14 cycles is necessary.

• For each burst which is longer than 1.8 ms a corre-

sponding gap time is necessary at some time in the

data stream. This gap time should be at least 4 times

longer than the burst.

• Up to 800 short bursts per second can be received

continuously.

Some examples for suitable data format are: NEC

Code (repetitive pulse), NEC Code (repetitive data),

Toshiba Micom Format, Sharp Code, RC5 Code,

RC6 Code, R-2000 Code, Sony Code.

When a disturbance signal is applied to the

TSOP12..WI1 it can still receive the data signal. How-

ever the sensitivity is reduced to that level that no

unexpected pulses will occur.

Some examples for such disturbance signals which

are suppressed by the TSOP12..WI1 are:

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

• Continuous signal at 38 kHz or at any other fre-

quency

• Signals from fluorescent lamps with electronic bal-

last with high or low modulation (see Figure 14 or Fig-

ure 15).

Figure 13. Vertical Directivity

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Figure 14. IR Signal from Fluorescent Lamp with low Modulation

Figure 15. IR Signal from Fluorescent Lamp with high Modulation

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Time ( ms )

16920

IR Signal from fluorescent

lamp with low modulation

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IR Signal from fluorescent

lamp with high modulation