Suppose the voltage is 3.5V, and the voltage of blue LED is usually between 2.9v and 3.9V. If it is cross-connected, the current is about 20mA, and the power of LED is controlled within 3W, then: P=(U 1+U2+...Ux)*I,

3w/0.02A=N*3.5V

150/3.5=N =42.8

So 40 LEDs crossing is not a problem.

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