Dropout Voltage Measurements - Analog Devices ADP151 User Manual

UG-116
2.83
2.82
2.81
2.80
2.79
2.78
2.77
0.01 0.1 1
I
LOAD
Figure 11. Output Voltage, V
OUT
V = 2.8 V, T
OUT

DROPOUT VOLTAGE MEASUREMENTS

Dropout voltage can be measured using the configurations
shown in Figure 7 and Figure 8. 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 to output
voltages above 2.2 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.
10 100 1000
(mA)
vs. Load Current, I at V = 3.2 V,
OUT IN
= 25°C
A
www.BDTIC.com/ADI
Rev. A | Page 6 of 12
Evaluation Board User Guide
The input supply voltage may need to be adjusted to account
for IR drops, especially if large load currents are used. Figure 12
shows the typical curve of dropout voltage measurements with
different load currents.
120
100
80
60
40
20
0
1 10
I
LOAD
Figure 12. Dropout Voltage vs. Load Currents (I
V = 2.8 V, T
OUT
100 1000
(mA)
)
LOAD
= 25°C
A