TSDP341.., TSDP343..
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Vishay Semiconductors
Rev. 1.1, 22-Aug-14
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
0101520
Time (ms)
16920
IR Signal
5
0101520
Time (ms)
16921
IR Signal
5
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)
