User manual

page 53
Analog System Lab Kit PRO
9.4 What should you submit
9.5 Exercise Set 9
experiment 9
Simulate the circuits and obtain the time response and transfer characteristics
of the system.
Take the plots of transfer characteristics and time response from oscilloscope
and compare it with simulation results.
Plot the average output voltage
V
f
V
T
VV
T
Tf
V
V
VVVV
T
V
T
2
1
1
1
p
ref
refp
av
ss
av refssp
ref
!
$
x
x
x
=
=
=
-
-
_i
as a function of reference voltage
V
f
V
T
VV
T
Tf
V
V
VVVV
T
V
T
2
1
1
1
p
ref
refp
av
ss
av refssp
ref
!
$
x
x
x
=
=
=
-
-
_i
and
obtain the plot; the plot will be linear.
Plot the duty cycle
V
f
V
T
VV
T
Tf
V
V
VVVV
T
V
T
2
1
1
1
p
ref
refp
av
ss
av refssp
ref
!
$
x
x
x
=
=
=
-
-
_i
as a function of reference voltage
V
f
V
T
VV
T
Tf
V
V
VVVV
T
V
T
2
1
1
1
p
ref
refp
av
ss
av refssp
ref
!
$
x
x
x
=
=
=
-
-
_i
and obtain the
plot, the plot will be linear. We have included the typical output waveform of
the SMPS circuit in Figure 9.2
Perform the same experiment with the specialized IC for DC-DC converter from
Texas Instrument TPS40200 and compare the characteristics of both systems.
1
2
3
4
Table 9.1: Variation of output voltage with reference voltage in a DC-DC converter
Table 9.2: Variation of duty cycle with reference voltage in a DC-DC converter
S.No. Reference Voltage Output Voltage
1
2
3
4
S.No. Reference Voltage Duty Cycle
V
f
V
T
VV
T
Tf
V
V
VVVV
T
V
T
2
1
1
1
p
ref
refp
av
ss
av refssp
ref
!
$
x
x
x
=
=
=
-
-
_i
1
2
3
4
+
L
R1
R2
R4R3
C1
VG1
VF1
VF2
V2
+
U
1
U2
Figure 9.2: (a) SMPS Circuit (b) Output Waveforms