Texas Instruments TPS40090EVM-002 - Manual (Page 13)

SLUU195 − June 2004
13 TPS40090 Multi-Phase Buck Converter and TPS2834 Drivers Steps-Down from 12-V to 1.5-V at 100 A
4.8 Compensation Components
The TPS40090 uses peak current mode control. Type II network is used here, which is
implemented to provide one zero and two poles. The first pole is placed at the origin to improve
DC regulation.
The ESR zero of the power stage is:
f
ESRZ
+ 1
2
p
R
C
C
OUT
+
354 kHz
The zero is placed near 3.96 kHz to produce a reasonable time constant.
f
Z
+
1
2
p
R11 C11
The second pole is placed at ESR zero (354 kHz).
f
P1
+
1
2
p
R11
ǒ
ǒ
C11 C12
Ǔ
ǒ
C11
)
C12
Ǔ
Ǔ
The resulting values selected for this design are:
•
R11 = 40.2 k
Ω
•
C11 = 1000 pF
•
C12 = 10 pF
(12)
(13)
(14)