Datasheet

Evaluation Board User Guide UG-117
Rev. A | Page 5 of 8
LINE REGULATION MEASUREMENTS
For line regulation measurements, the output of the regulator
is monitored while its input is varied. 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 mode during
this measurement, V
IN
must be varied between V
OUTNOM
+ 0.4 V
(or 2.2 V, whichever is greater) and V
INMAX
. For example, for an
ADP160 with a fixed 3.3 V output, V
IN
needs to be varied between
2.7 V and 5.5 V. This measurement can be repeated under differ-
ent load conditions. Figure 7 shows the typical line regulation
performance of an ADP160 with a fixed 3.3 V output.
08935-007
3.35
3.25
3.27
3.29
3.31
3.33
3.26
3.28
3.30
3.32
3.34
3.7 5.55.35.14.94.74.54.34.13.9
V
OUT
(V)
V
IN
(V)
LOAD = 1µA
LOAD = 100µA
LOAD = 1mA
LOAD = 10mA
LOAD = 100mA
LOAD = 150mA
Figure 7. Output Voltage (V
OUT
) vs. Input Voltage (V
IN
) at V
OUT
= 3.3 V, T
A
= 25°C
LOAD REGULATION MEASUREMENTS
For load regulation measurements, the output of the regulator
is monitored while the load is varied. For good load regulation,
the output must change as little as possible with varying load.
The input voltage must be held constant during this measure-
ment. The load current can be varied from 0 mA to 150 mA.
Figure 8 shows the typical load regulation performance of an
ADP160 with a fixed 3.3 V output for an input voltage of 3.7 V.
08935-008
3.35
3.25
3.27
3.29
3.31
3.33
3.26
3.28
3.30
3.32
3.34
0.001 0.01 1k1001010.1
I
LOAD
(mA)
V
OUT
(V)
Figure 8. Output Voltage (V
OUT
) vs. Load Current (I
OUT
) at V
IN
= 3.7 V,
V
OUT
= 3.3 V, T
A
= 25°C
DROPOUT VOLTAGE MEASUREMENTS
Dropout voltage can be measured using the configurations
shown in Figure 5 and Figure 6. 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.
The input supply voltage may need to be adjusted to account
for IR drops, especially if large load currents are used. Figure 9
shows the typical curve of dropout voltage measurements with
different load currents.
250
200
150
100
50
0
1110010
DROPOUT (mV)
I
LOAD
(mA)
08935-009
k
V
OUT
= 2V
V
OUT
= 3.3V
Figure 9. Dropout Voltage vs. Load Currents (I
LOAD,
), V
OUT
= 2.5 V and 3.3 V,
T
A
= 25°C