Datasheet

f
C
+
1
2p R1 C2 G
(Hertz)
f
P1
+
1
2p R2 C2
(Hz) f
P2
+
1
2p R3 C3
(Hz)
f
Z1
+
1
2p R2 C1
(Hz) f
Z2
+
1
2p R1 C3
(Hz)
R
BIAS
UDG−02189
+
R1
R3
C3
C2
(optional)
C1
R2
7
8
VREF
COMP
VFB
V
OUT
GAIN
180°
−90°
−270°
PHASE
+ 1
− 1
− 1
0 dB
MODULATOR GAIN
vs
SWITCHING FREQUENCY
Modulator
Gain - dB
f
SW
- Switching Frequency - Hz
100 1 k 10 k 100 k
ESR Zero, + 1
LC Filter, - 2
A
MOD
= V
IN(min)
/ V
RAMP
Resultant, - 1
V
C
PWM MODULATOR RELATIONSHIPS
V
S
D = V
C
/ V
S
TPS40060
TPS40061
SLUS543F –DECEMBER 2002–REVISED JUNE 2013 www.ti.com
Figure 8. Figure 9.
Figure 10. Type III Compensation of Configuration Figure 11. Type III Compensation Gain and Phase
The poles and zeros for a type III network are described in Equation 25.
(25)
The value of R1 is somewhat arbitrary, but influences other component values. A value between 50kΩ and
100kΩ usually yields reasonable values.
The unity gain frequency is described in Equation 26.
where
• G is the reciprocal of the modulator gain at f
C
(26)
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