4

Oct 24-06 Rev J

SP638 Synchronous Buck Controller

© 2006 Sipex Corporation

APPLICATION INFORMATION

Frequency

(Hz)

Error Amplifier Gain

Bandwidth Product

Condition:

C22 >> CP1, R1 >> RZ3

20 Log (RZ2/R1)

Gain

(dB)

Figure 6: Bode Plot of Type III Error Amplifier Compensation

Table 1. Input and Output Stage Components Selection Charts

Manufacturer

Series R

Isat

Size

Inductor Type

Website

mOhms

(A)

LxW(mm) Ht.(mm)

Cooper DR73-2R2

2.2

16.50

5.5

7.6x6.0

www.cooperet.com

Manufacturer

ESR

Ripple Current

Size

Voltage Capacitor

Website

Type

AVX 08053D475MAT

4.7

5

1.70

2.01X1.25 1.25

25.0 X5R Ceramic

www.avx.com

AVX 08056D226MAT

22

5

2.60

2.01X1.25 1.25

6.3 X5R Ceramic

www.avx.com

Manufacturer

RDS(on)

ID Current

Qg

Voltage Foot Print

Website

mΩ (max)

(A)

nC (Typ) nC (Max) (V)

Vishay Si7214DN

N-Channel

47

5.9

4.2

6.5

30

PowerPAK

1212-8

www.vishay.com

Note: Components highlighted in

bold are those used on the SP6138 Evaluation Board.

INDUCTORS - SURFACE MOUNT

CAPACITORS - SURFACE MOUNT

MOSFETS - SURFACE MOUNT

Manufacturer/Part No.

Inductance

(uH)

Manufacturer/Part No. Capacitance

(uF)

Inductor Specification

Capacitor Specification

MOSFET Specification

Manufacturer/Part No.

MOSFET

Note: Loop Compensation component calculations discussed in this

Datasheet can be quickly iterated with the Type III Loop Compensation

Calculator on the web at:

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