ADM7154CP-3.3EVALZ/ADM7154RD-1.8EVALZ/ADM7155CP-02-EVALZ User Guide
UG-696
Rev. 0 | Page 5 of 9
If the load current is greater than about 200 mA, it is recom-
mended that the user connect the voltmeter as close as possible
to the output capacitor to reduce the effects of IR drops.
LINE REGULATION
The output of the regulator is monitored and the input is varied
for line regulation measurements. For good line regulation, the
output must change as little as possible with varying input
levels. To ensure that the device is not in dropout during this
measurement, V
IN
must be varied between V
OUTNOM
+ 0.5 V (or
2.3 V, whichever is greater) and V
INMAX
. For example, for an
ADM7154 with a fixed 3.3 V output, V
IN
must be varied
between 3.8 V and 5.5 V. This measurement can be repeated under
different load conditions. Figure 5 shows the typical line
regulation performance of an ADM7154 with a fixed 3.3 V output.
Figure 5. Output Voltage (V
OUT
) vs. Input Voltage (V
IN
)
LOAD REGULATION
The output of the regulator is monitored and the load is varied
for load regulation measurements. For good load regulation, the
output must change as little as possible with varying loads. The
input voltage must be held constant during this measurement. The
load current can be varied from 0 mA to 600 mA. Figure 6 shows
the typical load regulation performance of an ADM7154 with a
fixed 3.3 V output for an input voltage of 3.8 V.
Figure 6. Output Voltage (V
OUT
) vs. Load Current (I
LOAD
)
DROPOUT VOLTAGE
Measure dropout voltage using the configuration shown in
Figure 3 and Figure 4. Dropout voltage is defined as the input to
output voltage differential when the input voltage is set to the
nominal output voltage. This applies only for output voltages
greater than 2.3 V. Dropout voltage increases with larger loads.
For more accurate measurements, use a second voltmeter to
monitor the input voltage across the input capacitor. The input
supply voltage may need adjusting to account for IR drops,
especially if large load currents are used. Figure 7 shows a typical
curve of dropout voltage measurements vs. load current.
Figure 7. Dropout Voltage vs. Load Current (I
LOAD
)
V
OUT
(V)
V
IN
(V)
5.55.04.54.03.5
3.27
3.33
3.32
3.31
3.30
3.29
3.28
I
LOAD
= 1mA
I
LOAD
= 10mA
I
LOAD
= 100mA
I
LOAD
= 200mA
I
LOAD
= 400mA
I
LOAD
= 600mA
12323-008
V
OUT
(V)
I
LOAD
(mA)
1000100101
3.27
3.28
3.29
3.30
3.31
3.32
3.33
12323-007
DROPOUT VOLTAGE (mV)
I
LOAD
(mA)
1000100101
0
160
140
120
100
80
60
40
20
12323-010
