Does output of TSOP1738 oscillate?

[aayush1]

I want to know about the output of the TSOP1738. As far as I know, its active low pin, and its output is HIGH normally and LOW while Detecting IR, but somewhere I read that its OUTPUT is also oscillating at 38Khz, and we need a RC circuit to convert that output into one pulse, is this TRUE? like explained in this article

 

[betwixt]

That article doesn't look right to me.

The 38KHz is filtered out before leaving the detector. I think what they mean to say is the output oscillates at the data rate of the IR transmitter, not the carrier rate. In other words, the binary pulse train of the IR command is filtered and used to clock the counter.

Brian.

 

[sharikbaig]

No, the output of TSOP1738 doesn't oscillate, It gives binary pulses as output. Afaik, Its function is to Filter & Decode an Infrared signal modulated by a carrier of 38Khz. So its input is of course oscillating, but output is simply a pulse train.

 

[ArticCynda]

I've had this issue a few years ago, and it turned out that, if the TSOP1738 receives a constant 38 kHz modulated signal for a long time (i.e hundreds of ms) then it will consider it noise and return the output to its floating state. The only way to fix this is to constantly modulate the signal with data.

 

[Audioguru]

Why read an article from somebody who knows nothing about it? Read the datasheet instead. It tells you EVERYTHING about what it does.
I think the article shows a circuit to switch something on or off when you push a button on a TV remote that sends many data pulses each time the button is pressed. So the data pulses are filtered away.

The Tsop IR receiver reduces its sensitivity when it receives continuous 38kHz because it assumes it is coming from a compact fluorescent light bulb that flickers continuously at about 38kHz.
Its datasheet shows that its data rate is fairly slow.

 

[aayush1]

Thanks for all your answers, I researched more and found that TSOP output doesn't oscillate. I have looked at datasheet, it doesn't explain anything about it

 

[Audioguru]

Thanks for all your answers, I researched more and found that TSOP output doesn't oscillate. I have looked at datasheet, it doesn't explain anything about it

The datasheet shows (in figure 8, Output Function) that with bursts of 38kHz input pulses, the output goes low during each burst. The bursts are data from a TV remote control. The datasheet assumes that you know what its automatic gain control (AGC) is used for.