Datasheet

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C1
R2
C2
15
+
7
8
+
14
13
+
12
9
R1
Modulator
DIFFO
COMP
FB
DROOP
VREF
VOUT
GSNS
L
OUT
V
OUT
C
OUT
R
ESR
R
OUT
V
REF
R
BIAS
UDG−04029
TPS40130DBT
R2 +
R1
AMOD(f)
(15)
AMOD +
V
VIN
0.4
(16)
AMOD(f) + AMOD
f
OP
f
C
(17)
C1 +
1
ǒ
2p f
OP
R2
Ǔ
(18)
C2 +
1
ǒ
2p f
ESRZ
R2
Ǔ
(19)
TPS40130
SLUS602B – JUNE 2004 – REVISED SEPTEMBER 2005
Figure 5. Compensation Components
The following expressions help in choosing components of the EA compensation network. It is recommended to
fix value of the resistor R1 first as it further simplifies adjustments of the output voltage without altering the
compensation network.
where AMOD is the modulator gain at DC
where AMOD(f) is the modulator gain at the crossover frequency
Introduction of output voltage droop as a measure to reduce amount of filter capacitors changes the transfer
function of the modulator as it is shown in Figure 6 and Figure 7 . The droop function introduces another zero in
the modulator gain function.
16
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