Datasheet

Vref
V
O
R1
R3
C1
C2
R2
C
O
R
O
gm
ea
COMP
FB
Type 2A Type 2B Type 1
C2
R3
C1
Z
OUT ESR
1
C R 2
=
´ ´ p
f
P
OUT L
1
f
C R 2
=
´ ´ p
ps L
Adc = gm R´
Z
OUT
C
P
s
1
2
V
Adc
V
s
1
2
æ ö
+
ç ÷
p ´
è ø
= ´
æ ö
+
ç ÷
p ´
è ø
f
f
TPS54360
SLVSBB4E –AUGUST 2012 –REVISED MARCH 2014 www.ti.com
Feature Description (continued)
(9)
(10)
(11)
(12)
8.3.16 Small Signal Model for Frequency Compensation
The TPS54360 uses a transconductance amplifier for the error amplifier and supports three of the commonly-
used frequency compensation circuits. Compensation circuits Type 2A, Type 2B, and Type 1 are shown in
Figure 31. Type 2 circuits are typically implemented in high bandwidth power-supply designs using low ESR
output capacitors. The Type 1 circuit is used with power-supply designs with high-ESR aluminum electrolytic or
tantalum capacitors. Equation 13 and Equation 14 relate the frequency response of the amplifier to the small
signal model in Figure 31. The open-loop gain and bandwidth are modeled using the R
O
and C
O
shown in
Figure 31. See the application section for a design example using a Type 2A network with a low ESR output
capacitor.
Equation 13 through Equation 22 are provided as a reference. An alternative is to use WEBENCH software tools
to create a design based on the power supply requirements.
Figure 31. Types of Frequency Compensation
20 Submit Documentation Feedback Copyright © 2012–2014, Texas Instruments Incorporated
Product Folder Links: TPS54360