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SP6126_1 Datasheet, PDF (5/8 Pages) Sipex Corporation – Evaluation Board Manual | |||
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LOOP COMPENSATION
The SP6126 includes Type-II internal compensation components for loop
compensation. External compensation components are not required for systems with
tantalum or aluminum electrolytic output capacitors with sufficiently high ESR. Use the
condition below as a guideline to determine whether or not the internal compensation is
sufficient for your design.
Type-II internal compensation is sufficient if the following condition is met:
f < f ESRZERO
DBPOLE
â¦â¦â¦â¦â¦â¦. (1)
where:
1
f ESRZERO = 2.Ï .RESR .COUT â¦â¦â¦.. (2)
1
f DBPOLE = 2.Ï . L â
COUT â¦â¦â¦â¦ (3)
Creating a Type-III compensation Network
The above condition requires the ESR zero to be at a lower frequency than the double-
pole from the LC filter. If this condition is not met, Type-III compensation should be
used and can be accomplished by placing a series RC combination in parallel with R1
as shown below. The value of CZ can be calculated as follows and RZ selected from
table 1.
CZ = L â
C â¦â¦â¦â¦.. (4)
R1
fESRZERO/fDBPOLE RZ
1X
50K
2X
40K
3X
30K
5X
10K
>= 10X
2K
Table1- Selection of RZ
5
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