TSOP2138UH1 Ver la hoja de datos (PDF) - Vishay Semiconductors

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TSOP2138UH1

Photo Modules for PCM Remote Control Systems

Vishay Semiconductors 

TSOP21..UH1

Vishay Telefunken

Suitable Data Format

The circuit of the TSOP21..UH1 is designed in that

way that unexpected output pulses due to noise or dis-

turbance 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 and dis-

turbance signal are carrier frequency, burst length and

duty cycle.

The data signal should fullfill the following condition:

• Carrier frequency should be close to center

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

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

• After each burst which is between 6 cycles and 70

cycles a gap time of at least 10 cycles is

neccessary.

• For each burst which is longer than 1.8ms a

corresponding 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

TSOP21..UH1 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 TSOP21..UH1 are:

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

• Continuous signal at 38kHz or at any other

frequency

• Signals from fluorescent lamps with electronic

ballast (an example of the signal modulation is

shown in the figure below).

0

5

10

15

20

time [ms]

IR Signal from Fluorescent Lamp with low Modulation

Document Number 82123

Rev. 5, 30-Mar-01

www.vishay.com

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