My ultrasonic sensor works, but I don't understand why!

Hi there,

I’m using a Seeedstudio ultrasonic sensor with a Dagu Micro Magician V2. This is essentially an Arduino compatible board that runs at 3.3V.

Now, the thing I don’t understand is, I’m supplying the Ultrasonic sensor with 3.3V (I’ve measured the voltage across its pins with a multimeter) and it’s still working, sending back seemingly accurate distance measurements, even though the specifications of the Ultrasonic sensor and question 10 on its product page (the one titled ‘Would this work with 3.5 Volts also?’) seem to suggest that the sensor should only work with 5V.

I’m happy with this, I’m assuming that I just got a batch where they were using 3.3V compatible chips, but my questions would be

  • Am I making a silly mistake and missing something obvious here?
  • Can anybody from SeeedStudio confirm that 3.3V compatibility will remain? So that I can use it in future designs.
  • Does anyone have the part numbers for the ICs on the back (they seem to have been removed from the sensor I’ve got)? So that I can confirm the 3.3V compatibility in the data sheet.

Thank you in advance for your time.