34063

Design Formula Table

Calculation

Step-Up

Step-Down

Voltage-Inverting

ton/toff

out

V

+

−

in

V

+ V

F

out

V

+ V

F

in

V

(min)

−

satV

(ton+toff)max

1

f

in

V

(min)

−V

sat

−

outV

1

f

in

V

+ V

sat

1

min

f

CT

4.0 x 10

-5

ton

4.0x10

-5

ton

4.0 x 10

-5

lpk(switch)





2



+ 1

2

t

I

on



+ 1



2I

out(max)

I



on

t





(max)









RSC

0.3/lpk(switch)

0.3/lpk(switch)

0.3/lpk(switch)

L(min)



−





−

V

in(min)

V

sat





−



in

V

sat

V

 ×t

on (max)



V

in (min)

V

sat

V

out



× on(max)





I





t

on(max)



I

pk ( switch )







I

pk ( switch )







pk ( switch )



CO

9

I

out ton

I

pk ( switch )

( t

+

t

)

9

tI

V

ripple ( pp )

8V

ripple ( pp )

V

ripple ( pp )

TERMS AND DEFINITIONS

Vsat -

Saturation voltage of the output switch.

VF -

Forward voltage drop of the output rectifier.

The following power supply characteristics must be chosen:



R



=

.1 25 1 +

Vout





1

R 

Vin -

Nominal input voltage.

Vout -

Desired output voltage,

Iout -

Desired output current.

fmin -

Minimum desired output switching frequency at the selected values of Vin and IO.

Vripple(p-p) –Desired peack-to-peack output ripple voltage. In practice, the calculated capacitor value will need to be increased due to its

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

line and load regulation.

Ordering Information

O R DER I NG NU M B ER

P AC K AGE

M AR K I NG

34063A

SOP-8 /DIP-8

MC34063A

Address :

6A06--6A07

Rm 6A07,Changyin Office Building ,No.88,Yong Ding Road,Hai Dian District ,Beijing

Postalcode:100039

Tel: 86-010-58895780 / 81 / 82 / 83 / 84

Fax : 010-58895793

Http://www.estek.com.cn

Email:sales@estek.com.cn

REV No:01-060810

7

BEIJING ESTEK ELECTRONICS CO.,LTD