Evaluation Board User Guide
UG-157
Rev. 0 | Page 5 of 12
Load Regulation of LDO
Dropout Voltage of LDO
For load regulation measurements, the regulator output is
monitored while the load is varied. For good load regulation,
the output must change as little as possible with varying loads.
The input voltage must be held constant during this measure-
ment. The load current can be varied from 0 mA to 150 mA.
Figure 6 shows the typical load regulation performance of the
LDO with fixed 2.8 V output for an input voltage of 3.3 V.
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 above 2.3 V.
Dropout voltage increases with larger loads. For more accurate
measurements, a second voltmeter can be used to monitor the
input voltage across the input capacitor. The input supply
voltage may need to be adjusted to account for IR drops,
especially if large load currents are used.
2.790
2.792
2.794
2.796
2.798
2.800
2.802
2.804
2.806
2.808
2.810
0
0.02
0.04
0.06
0.08
0.10
0.12
0.14
I
OUT
(A)
V
OUT
(V
)
0913
7-00
6
Ground Current Consumption of LDO
Ground current measurements can determine how much
current the internal circuits of the regulator consume while the
circuits perform the regulation function. To be efficient, the
regulator needs to consume as little current as possible.
Typically, the regulator uses the maximum current when
supplying its largest load level (150 mA). When the device is
disabled, the ground current drops to less than 1 mA.
Figure 6. LDO Load Regulation
