User manual

page 64
Analog System Lab Kit PRO
experiment 12
The goal of the experiment is to congure the on-board evaluation module
TPS40200 on the ASLK PRO Kit as a switched mode power supply that
can provide a regulated output voltage of 5V or 3.3V for an input whose
range is 6V-15V.
The TPS40200 evaluation module included on ASLK PRO. Kit uses the TPS40200
non synchronous buck converter to provide a resistor-selected, 3.3V or 5V output that
delivers up to 2.5A from up to 16V input bus. See Figure 12-1 for a schematic diagram
of the EVM. The evaluation module operates from a single supply and uses the single
12.1 Brief theory and motivation
Goal of the experiment
Figure 12.1: Schematic of the on-board EVM
P–channel Power FET and Schottky diode to produce a low cost buck converter. The
regulated output of the EVM is resistance-selected and can be adjusted within the
limited range by making the changes in the feedback loop, as shown below.
The feedback factor
0.7
1
V
V
VV
RR
R
VVdutycycle
TP
TP
M
R
TP
J
TP
TP
R
C
209207
209
205
207
209
20
201
203
204
201
213
out
ref
ref
out in
8
$
X
=
=
=
=
b
b
+
can be changed by changing feedback resistance R209 to
adjust the output. But in ASLK PRO, we do not have the provision of changing R209.
We can therefore achieve this task by connecting an external resistance of suitable
value between the terminals TP8 and the ground.
0.7
1
V
V
V V
R R
R
V Vdutycycle
TP
TP
M
R
TP
J
TP
TP
R
C
209 207
209
205
207
209
20
201
203
204
201
213
out
ref
ref
out in
8
$
X
=
=
=
=
b
b
+
RC
1
SS
2
COMP
3
FB
4
GND
5
DRV
6
ISNS
7
VDD
8
TPS40200
RC
SS
COMP
FB
VDD
ISNS
DRV
GND
U4
4
3
6 5 2 1
Q101
FDC5614P
VIN 6 – 15V
VOUT 3.3V or 5V
VIN
VOUT
GATE
SRC
DRAIN
RC
SS
COMP
FB
ISNS
DRV
DC/DC IN
HD143
VOUT
R3
4K7
C202
68pF
C203
220nF
C204
220nF
C205
470pF
C206
4.7nF
C207
33pF
C208
100nF
C211
10uF
C212
10uF
C213
470pF
C214
470nF
C201
220uF
C209
330uF
C210
330uF
L201
33uH
R201
100K
R202
0.03
R203
1K
R204
0E
R 205
100K
R 206
25.5E
R207
100K
R208
49.9
R209
27K4
R210
1M
R211
41K2
HD120
TP2
HD121
TP3
HD122
TP1
HD123
TP8
HD124
TP6
HD125
TP9
HD126
TP4
HD127
TP7
HD128
TP5
LD3
JP9
D201
MBRS340
CN6
VOUT
CN5
VIN
JP8
VCC+10
@ 0.125 – 2.5A
3.3V
5V
HD142
Vin