Slide 1 Slide 2 Slide 3 Slide 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9 Slide 10 Slide 11 Slide 12 Slide 13 Slide 14 Slide 15 Slide 16 Slide 17 Slide 18 Slide 19 Slide 20 Slide 21 Slide 22 Slide 23 Slide 24 Slide 25 Slide 26 Slide 27 Slide 28 Slide 29 Slide 30 Slide 31 Slide 32 Slide 33 Slide 34 Slide 35 Slide 36 Slide 37 Slide 38 Slide 39 Slide 40 Slide 41 Slide 42 Slide 43 Slide 44 Slide 45 Slide 46 Slide 47 Slide 48 Slide 49 Slide 50 Slide 51 Slide 52 Slide 53 Slide 54 Slide 55 Slide 56 Slide 57 Slide 58 Slide 59 Slide 60 Slide 61 Slide 62 Slide 63 Slide 64 Slide 65 Slide 66 Slide 67 Slide 68 Slide 69 Slide 70 Product List
Electromagnetic Noise Reduction Slide 37

Lowering the power-supply voltage is a straightforward way to reduce noise emissions. That’s because noise power (P) varies with the square of the voltage, since P=VI=V(V/Z)=V2Z. Thus, when you lower Vcc from 5V to 3.3V, the noise level will decrease significantly. (Theoretically, it will drop by 57 percent; in actuality, though, the decrease will be less because much of the microcontroller’s internal circuitry is run from a voltage regulator and therefore is independent of the applied voltage.) Using a smaller Vcc also allows the use of lower-voltage, larger-value filter capacitors.

PTM Published on: 2011-11-02