Feb21-07

SP7661 Evaluation Manual

©2007 Sipex Corporation

Page 7 of 11

Step by step design procedures:

Choose

fs/10

fco

=

60Khz

600Khz/10

fco

=

=

Calculate fp_LC, the double pole frequency of the filter

)

C

L

(

2

1

fp_LC

⋅

=

π

12kHz

11.99kHz

)

80uF

2.2uH

2π

1

fp_LC

≈

=

⋅

⋅

=

Calculate fz_ESR , the ESR zero frequency

Cout

Cesr

2π

1

fz_ESR

⋅

⋅

=

kHz

µF

mΩ

π

ESR

fz

663

)

80

(

)

3

(

2

1

_

=

⋅

⋅

=

Select R1 component value such that 10k

Ω ≤ R1 ≤ 100kΩ

R1 = 10k

Ω, 1%

1

8

.

1

2

−









=

V

Vout

R

R

Ω

≈

Ω

=

−









Ω

=

3160

3200

1

8

.

3

.

3

10

2

V

V

K

R

Note: Loop Compensation component calculations discussed in this

section are further elaborated in the application note #ANP16, “Loop

Compensation of Voltage-Mode Buck Converters”.

These calculations shown here can be quickly iterated with the Type III

Loop Compensation Calculator on the web at:

www.sipex.com/files/Application-Notes/TypeIIICalculator.xls