MC34063A, MC33063A

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10

Calculation

Step–Up

Step–Down

Voltage–Inverting

Vout ) VF * Vin(min)

V

in(min) *

Vsat

Vout ) VF

V

in(min) *

Vsat * Vout

|Vout| ) VF

V

in *

Vsat

1

f

1

f

1

f

ton ) toff

ton

t

off

) 1

ton ) toff

ton

t

off

) 1

ton ) toff

ton

t

off

) 1

2I

out(max)

ton

t

off

) 1

2I

out(max)

2I

out(max)

ton

t

off

) 1

(V

in(min) *

Vsat)

I

pk(switch)

t

on(max)

(V

in(min) *

Vsat * Vout)

I

pk(switch)

t

on(max)

(V

in(min) *

Vsat)

I

pk(switch)

t

on(max)

9

Ioutton

V

ripple(pp)

I

pk(switch)

(ton ) toff)

8V

ripple(pp)

9

Ioutton

V

ripple(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 14. Design Formula Table