- September 12, 2009
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The minimum input voltage is not the problem. But at what level your led chip thinks that a voltage is high.
WS2812B datasheet says:
Input voltage level
VIH DIN,SET 0.7VDD —— —— V
VIL DIN,SET —— —— 0.3 VDD V
So everything from 0.7*Vdd is considered high (1). And everything below 0.3*Vdd is considered low. Lets say your power supply gives you a perfect 5V. Then you need 0.7*5=3.5V to get a clear and stable high signal. With 3.3V we just dont get there. Yeah there is a little room for error, but you should drive your electronics always in spec .
WS2812B datasheet says:
Input voltage level
VIH DIN,SET 0.7VDD —— —— V
VIL DIN,SET —— —— 0.3 VDD V
So everything from 0.7*Vdd is considered high (1). And everything below 0.3*Vdd is considered low. Lets say your power supply gives you a perfect 5V. Then you need 0.7*5=3.5V to get a clear and stable high signal. With 3.3V we just dont get there. Yeah there is a little room for error, but you should drive your electronics always in spec .