A circuit was setup to detect obstacle (proximity sensor) using IR transmitter which uses Arduino to generate 40 kHz Frequency (the frequency was checked using a digital oscilloscope and it displays 40 kHz) and TSMP58000 as IR receiver, but the voltage at the output of the IR receiver when an IR pulse gets detected is seen as 3V instead of a value ~0V .What could be the issue?

Receiver used - http://www.vishay.com/docs/82485/tsmp58000.pdf (it receives in 20 kHz - 40 kHz range)

The screen shot of the transmitter and receiver circuits are as below where 4 is connected to the arduino pin and IR led is connected to the ground. External Power supply is used to power the IR receiver. Where common ground is used for both.

 

The way I read this, the output is supposed to be, "high" when it detects the carrier frequency.
So what's the problem?

 

The way I read this, the output is supposed to be, "high" when it detects the carrier frequency.
So what's the problem?

5th bullet point is "Output active low"

 

5th bullet point is "Output active low"

Bullet point 7 seems to contradict this, thus the confusion.
No Truth Table provided.
I ask the Thread Starter: Is the output also high for no signal?

 

Signal output is high until a carrier is present, then its low

 

And FWIW, this is the usual behavior of such receivers. There are only a few that work the other way, and they're not easy to find.

 

Bullet point 7 seems to contradict this, thus the confusion.
No Truth Table provided.
I ask the Thread Starter: Is the output also high for no signal?

Yes the output is high for no signal.

 

It don't work like your thinking if you send a steady 40 kHz signal it see's it as noise and will not pull low. gate the signal with 1mS breaks and it should work like you want it to.

 

Good point. These things will go low when they spot the carrier but will not hold that for long. I'm not sure where this is in the datasheet.