TSOP6938 Просмотр технического описания (PDF) - Vaishali Semiconductor
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TSOP6938 Datasheet PDF : 15 Pages
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VISHAY
TSOP69..
Vishay Semiconductors
Suitable Data Format
The circuit of the TSOP69.. is designed in that way
that unexpected output pulses due to noise or distur-
bance signals are avoided. A bandpass filter, a limiter
stage, an integrator stage and an automatic gain con-
trol 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 6 cycles/burst or longer.
• After each burst which is between 6 cycles and 120
cycles a gap time of at least 10 cycles is necessary.
• For each burst which is longer than 3.2 ms a corre-
sponding gap time is necessary at some time in the
data stream. This gap time should have at least same
length as the burst.
• Up to 2200 short bursts per second can be received
continuously.
Some examples for suitable data format are: NEC
Code, Toshiba Micom Format, Sharp Code, RC5
Code, RC6 Code, RCMM Code, R-2000 Code,
RECS-80 Code.
When a disturbance signal is applied to the TSOP69..
it can still receive the data signal. However the sensi-
tivity is reduced to that level that no unexpected
pulses will occur.
Some examples for such disturbance signals which
are suppressed by the TSOP69.. 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-
lasts with various kinds of modulation
(see examples in Figure 13 and Figure 14).
IR Signal from fluorescent
lamp with low modulation
0
16920
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10
15
20
Time ( ms )
Figure 13. IR Signal from Fluorescent Lamp with low Modulation
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1
0
0
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4
6
8
10
18659
Time ( ms )
Figure 14. IR Signal from a Fluorescent Lamp with Spikes
Document Number 84687
Rev. 1.0, 01-Mar-05
www.vishay.com
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