MC34063A, MC33063A, SC34063A, SC33063A, NCV33063A

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11

Calculation

Step−Up

Step−Down

Voltage−Inverting

Vout ) VF * Vin(min)

Vin(min) * Vsat

Vout ) VF

Vin(min) * Vsat * Vout

|Vout| ) VF

Vin * Vsat

1

f

1

f

1

f

ton ) toff

ton

toff

) 1

ton ) toff

ton

toff

) 1

ton ) toff

ton

toff

) 1

2Iout(max)

ton

toff

) 1

2Iout(max)

2Iout(max)

ton

toff

) 1

(Vin(min) * Vsat)

Ipk(switch)

ton(max)

(Vin(min) * Vsat * Vout)

Ipk(switch)

ton(max)

(Vin(min) * Vsat)

Ipk(switch)

ton(max)

9

Ioutton

Vripple(pp)

Ipk(switch)(ton ) toff)

8Vripple(pp)

9

Ioutton

Vripple(pp)

The following power supply characteristics must be chosen:

equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it will directly affect the

line and load regulation.

NOTE: For further information refer to Application Note AN920A/D and AN954/D.

R2

R1

Figure 17. Design Formula Table