If you tun off the supply voltage, the chip will not operate. Simple as that. "Common sense" tells you this.
However, if you send data to it with the supply voltage turned off, the protection diode will feed current from the data input into the supply terminal - VDD. Because the protection diode is not rated to do this, you may damage the chip.
So the point is - this is something you would never do!
But just in case, this is one reason why you use a 330 or 470 Ohm resistor in series with the data feed to the first chip in any separate strip.
thank you very much for the explanation.
I take this opportunity to ask you what advice you give me to do what I thought, that is to shutdown a single LED if its corresponding switch/sensor is off.
Everything must be done electronically, acting on a signal that wants the led to be on, this is because arduino would be far away and doesn't know if the sensor is active or not.
Even more interesting would be to have 3 switches per led, each controlling a single color.
From what I understand I should replace the first 24bit with a signal equal to 24x "code 0" (switch any T1 to T0), how is that possible?
Thanks in advance