Datasheet

VO
R
L
VC
fp
fz
Adc
gm
ps
R
ESR
C
OUT
s
1+
2 × z
vo
= Adc
vc
s
1+
2 × p
æ ö
ç ÷
p ¦
è ø
´
æ ö
ç ÷
p ¦
è ø
ps L
Adc = gm R´
¦
´ ´ p
OUT L
1
p =
C R 2
¦
´ ´ p
OUT ESR
1
z =
C R 2
Vref
VO
R1
R3
C1
C2
R2
CO
5pF
RO
gm
ea
COMP
VSENSE
Type 2A
Type 2B
R3
C1
TPS57112-Q1
www.ti.com SLVSAL8 –DECEMBER 2010
Figure 32. Simple Small Signal Model and Frequency Response for Peak Current Mode Control
(11)
(12)
(13)
vertical spacer
(14)
SMALL SIGNAL MODEL FOR FREQUENCY COMPENSATION
The TPS57112-Q1 uses a transconductance amplifier for the error amplifier and readily supports two of the
commonly used frequency compensation circuits. The compensation circuits are shown in Figure 33. The Type 2
circuits are most likely implemented in high bandwidth power supply designs using low ESR output capacitors. In
Type 2A, one additional high frequency pole is added to attenuate high frequency noise.
Figure 33. Types of Frequency Compensation
Copyright © 2010, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Link(s): TPS57112-Q1