Datasheet

EVAL-ADP170/ADP171
Rev. 0 | Page 5 of 8
LINE REGULATION
For line regulation measurements, the output of the regulator is
monitored while its input varies. For good line regulation, the
output (V
OUT
) must change as little as possible with varying
input (V
IN
) 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 1.6 V, whichever is greater) and V
INMAX
. For example,
for an ADP170 with fixed 1.8 V output, V
IN
needs to be varied
between 2.3 V and 5.5 V. This measurement can be repeated
under different load conditions. Figure 5 shows the typical line
regulation performance of an ADP170 with fixed 1.8 V output.
V
IN
(V)
V
OUT
(V)
2.32.1 2.5 2.7 2.9 3.1 3.3 3.5
1.798
1.799
1.800
1.801
1.802
1.803
1.804
1.805
LOAD = 100µA
LOAD = 1mA
LOAD = 10mA
LOAD = 100mA
LOAD = 200mA
LOAD = 300mA
07723-007
Figure 5. Output Voltage vs. Input Voltage
LOAD REGULATION
For load regulation measurements, the output of the regulator is
monitored while the load varies. For good load regulation, the
output must change as little as possible with varying load current.
The input voltage must be held constant during this measurement.
The load current can be varied from 0 mA to 150 mA. Figure 6
shows the typical load regulation performance of an ADP170 with
fixed 1.8 V output for an input voltage of 2.3 V.
0.10.01 1k
LOAD CURRENT (mA)
110100
V
OUT
(V)
1.798
1.799
1.800
1.801
1.802
1.803
1.804
07723-006
Figure 6. Output Voltage vs. Load Current
DROPOUT VOLTAGE
Dropout voltage can be measured using the configuration
shown in 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 1.6 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 to be adjusted to account for IR drops
due to trace resistance, especially if large load currents are used.
Figure 7 shows a typical curve of dropout voltage measurements
with different load currents.
70
60
50
40
30
20
10
0
1 10 100 1k
DROPOUT VOLTAGE (mV)
LOAD CURRENT (mA)
T
A
= 25°C
07723-012
Figure 7. Dropout Voltage vs. Load Current