TSDP341.., TSDP343..

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Vishay Semiconductors

Rev. 1.6, 02-Aug-2021

5

Document Number: 82667

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SUITABLE DATA FORMAT

Theses receivers are designed to suppress spurious output

pulses due to noise or optical disturbances. The devices can

distinguish data signals from noise due to differences in

frequency, burst length, and envelope duty cycle. For

optimum sensitivity, the data’s modulation frequency

should be close to the device’s band-pass center frequency

(e.g. 38.4 kHz) and fulfill the conditions in the table below.

When a data signal is applied to the receiver in the presence

of noise, the sensitivity of the receiver is automatically

reduced by the AGC to insure that no spurious pulses are

present at the receiver’s output. Some examples of noise

which is suppressed:

• DC light (e.g. from tungsten bulbs sunlight)

• Continuous signals at any frequency

• Strongly or weakly modulated patterns from fluorescent

lamps with electronic ballasts (see Fig. 13 or Fig. 14).

Fig. 13 - IR Disturbance from Fluorescent Lamp

With Low Modulation

Fig. 14 - IR Disturbance from Fluorescent Lamp

With High Modulation

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Time (ms)

TSDP341..

TSDP343..

Minimum burst length

6 cycles/burst

6 cycles/burst

After each burst of length

A gap time is required of

6 to 70 cycles

≥ 7 cycles

6 to 35 cycles

≥ 7 cycles

For bursts greater than

a minimum gap time in the data stream is needed of

70 cycles

> 1.2 x burst length

35 cycles

> 6 x burst length

Maximum number of continuous short bursts/second

3000

3000

Suppression of interference from fluorescent lamps

Mildly modulated noise patterns

are suppressed (Fig. 13)

Strongly modulated noise patterns

are suppressed (Fig. 14)