TS34063

7-8

2003/12 rev. C

Design Formula Table

Test

Step Up

Step Down

Voltage Inverting

Vsat

Vcc

Vin

Vf

Vout

−

−

+

(min)

(min)

Vout

Vsat

Vcc

Vf

Vout

−

−

+

Vsat

Vcc

Vf

Vout

−

+

|

|

(

min

1

f

min

1

f

min

1

f

CT

4.0 x 10

4.0 x 10

4.0 x 10

Ipk(switch)

2Iout(max)

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+ 1

toff

ton

2Iout(max)

2Iout(max)

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+ 1

toff

ton

Rsc

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

)

(

3

.

0

switch

Ipk

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

)

(

3

.

0

switch

Ipk

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

)

(

3

.

0

switch

Ipk

L(min)

)

ton(

)

Ipk(switch

Vsat

)

Vin(

max

*

min

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

(max)

*

)

(

(min)

ton

switch

Ipk

Vout

Vsat

Vin

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

−

(max)

*

)

(

(min)

ton

switch

Ipk

Vsat

Vin

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

Co

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

)

(

*

9

pp

Vripple

ton

Iout

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

)

(

8

)

)(

(

pp

Vripple

toff

ton

switch

Ipk

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

)

(

*

9

pp

Vripple

ton

Iout

Terms and Definitions

Vsat = Saturation Voltage of the output switch.

Vf = Forward Voltage drop of the rectifier.

The following power supply characteristics must be chosen:

Vin= Normal input voltage

Vout: Desied Output voltage, |Vout| =1.25 (1+R2 / R1)

Iout : Desired output current.

fmin : Minimum desired output switching frequency at the selected values for Vin and Io.

Vripple(p-p): Desired peak-to-peak output ripple voltage. in practice, the calculated capacitor value will need to be

increased due to its 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.