Datasheet

P2
1 1
f 201kHz
2 R3 C2 2 24 k 33 pF
= = =
p ´ ´ p ´ W ´
Z1
1 1
f 4.42 kHz
2 R3 C1 2 24 k 1.5 nF
= = =
p ´ ´ p ´ W ´
BUCK CFB
REF
C
OUTx OUT
C
Gm R3 K
V
f
2 C V
1mS 24 k 8.33 S 0.8 V
f 50.9 kHz
2 100 μF 5 V
´ ´
= ´
p ´
´ W ´ ´
= =
p ´ ´
SW
C1 1.5 nF
C2 33 pF
f 400 kHz
2 24k 1.5 nF 1
2 R3 C1 1
2
2
= = =
æ ö æ ö
p ´ W ´ -
p ´ ´ -
ç ÷
ç ÷
è ø
è ø
C
10 10
C1 1.33 nF
2 R3 f 2 24 k 50 kHz
= = =
p ´ ´ p ´ W ´
C OUT OUTx
BUCK CFB REF BUCK CFB REF
2 f V C
2 50 kHz 5 V 100μF
R3 23.57 k
Gm K V Gm K V
p ´ ´ ´
p ´ ´ ´
= = = W
´ ´ ´ ´
V
REF
R
L
COMP
VSENSE
Type 2A
Gm
BUCK
R
ESR
C2
C1
R3
R1
R2
V
OUT
R0
C
OUT
TPS43330-Q1
TPS43332-Q1
SLVSA82E –MARCH 2011–REVISED APRIL 2013 www.ti.com
Selection of Components for Type II Compensation
Figure 27. Buck Compensation Components
where V
OUT
= 5 V, C
OUT
= 100 µF, Gm
BUCK
= 1 mS, V
REF
= 0.8 V, K
CFB
= 0.125 / R
SENSE
= 8.33 S (0.125 is an
internal constant)
Use the standard value of R3 = 24 kΩ.
Use the standard value of 1.5 nF.
The resulting bandwidth of buck converter f
C
f
C
is close to the target bandwidth of 50 kHz.
The resulting zero frequency f
Z1
f
Z1
is close to the f
C
/ 10 guideline of 5 kHz.
The second pole frequency f
P2
f
P2
is close to the f
SW
/ 2 guideline of 200 kHz. Hence, the design satisfies all requirements for a good loop.
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