TSOP48..YA1

Vishay Telefunken

3 (7)

Rev. 4, 29-Mar 01

www.vishay.com

Document Number 82131

Suitable Data Format

The circuit of the TSOP48..YA1 is designed in that way

that unexpected output pulses due to noise or

disturbance 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

disturbance 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 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 1.8ms a

corresponding 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, Toshiba Micom Format, Sharp Code, RC5

Code, RC6 Code, R–2000 Code.

When a disturbance signal is applied to the

TSOP48..YA1 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 TSOP48..YA1 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 with high or low modulation (see Figure A or

Figure B).

0

5

10

15

20

time [ms]

Figure A: IR Signal from Fluorescent Lamp with low Modulation

0

5

10

15

20

time [s]

Figure B: IR Signal from Fluorescent Lamp with high Modulation