Evaluation Board User Guide
UG-439
Rev. A | Page 5 of 13
Measuring Load Regulation of the Buck Regulator
Test the load regulation by increasing the load at the output and
examining the change in output voltage. The input voltage must be
held constant during this measurement. To minimize voltage drop,
use short low resistance wires, especially for loads approaching
maximum current. The buck regulator load regulation plots for
V
OUT2
= 3.3 V and V
OUT2
= 1.8 V are shown in Figure 7 and
Figure 8, respectively.
Figure 7. Buck Load Regulation, V
OUT2
= 3.3 V
Figure 8. Buck Load Regulation, V
OUT2
= 1.8 V
Measuring Line Regulation of the Buck Regulator
Test the line regulation by increasing the input voltage and
examining the change in the output voltage. The buck regulator
line regulation plots for V
OUT2
= 3.3 V and V
OUT2
= 1.8 V are
shown in Figure 9 and Figure 10, respectively.
Figure 9. Buck Regulator Line Regulation, V
OUT2
= 3.3 V
Figure 10. Buck Regulator Line Regulation, V
OUT2
= 1.8 V
3.271
3.272
3.273
3.274
3.275
3.276
3.277
0
200
400
600
800
1000
1200
V
O
UT
2
(V)
I
LOAD
(mA)
V
IN
= 3.8V
V
IN
= 4.3V
V
IN
= 5.5V
10895-
208
1.7985
1.7980
1.7975
1.7970
1.7965
1.7950
1.7955
1.7960
0
1200
1100
1000
900
800
700
600
500
400
300
200
100
V
O
UT
2
(V)
I
LOAD
(mA)
V
IN
= 2.3V
V
IN
= 3.6V
V
IN
= 5.5V
10895-
108
3.265
3.266
3.267
3.268
3.269
3.270
3.271
3.272
3.273
3.274
3.275
3.276
3.277
3.8
4.3
4.8
5.3
V
O
UT
2
(V)
V
IN2
(V)
NO LOAD
I
LOAD
= 200mA
I
LOAD
= 800mA
I
LOAD
= 1200mA
10895-
210
1.7990
1.7985
1.7980
1.7975
1.7970
1.7965
1.7950
1.7955
1.7960
2.0
2.5
3.0
3.5
4.0
5.5
5.0
4.5
V
O
UT
2
(V)
V
IN2
(V)
I
LOAD
= 0mA
I
LOAD
= 200mA
I
LOAD
= 800mA
I
LOAD
= 1200mA
10895-
109
