EVAL-ADP1720_15 Datasheet, PDF (5/8 Pages) Analog Devices – Evaluation Board for the ADP1720

OUTPUT VOLTAGE MEASUREMENTS
VOLTAGE SOURCE
+
_
EVAL-ADP1720
GND
U1
C1
C2
EVAL-ADP1720
GND
VOLTAGE METER
V
_
+
J1
VIN
R1
R2
VOUT
LOAD
J2
GND
EN
GND/ADJ
GND
Figure 5.
Figure 5 shows how the evaluation board can be connected to a
voltage source and a voltage meter for some basic output voltage
accuracy measurements. A resistor can be used as the load for
the regulator. Ensure the resistor has a power rating adequate
to handle the power expected to be dissipated across it. An elec-
tronic load can be used as an alternative. Ensure the voltage source
used can supply adequate current for the expected load levels.
Follow these steps to connect to a voltage source and voltage meter:
1. Connect the negative terminal (−) of the voltage source to
one of the GND pads on the evaluation board.
2. Connect the positive terminal (+) of the voltage source to
the VIN pad of the evaluation board.
3. Connect a load between the VOUT pad and one of the
GND pads.
4. Connect the negative terminal (−) of the voltage meter to
one of the GND pads, and the positive terminal (+) of the
voltage meter to the VOUT pad.
5. The voltage source can now be turned on. If J1 is inserted
(this connects EN to VIN for automatic startup), then the
regulator powers up.
LINE REGULATION
For line regulation measurements, the regulator’s output 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 the device is not in dropout during this
measurement, VIN must be varied between VOUTNOM + 0.5 V
(or 4 V, whichever is greater) to VINMAX. For an ADP1720 with
5 V output, this means VIN needs to be varied between 5.5 V
and 28 V. This measurement can be repeated under different
load conditions. Figure 6 shows the typical line regulation
performance of an ADP1720 with 5 V output.
5.010
5.008
5.006
5.004
I_LOAD = 10µA
I_LOAD = 100µA
I_LOAD = 1mA
I_LOAD = 10mA
I_LOAD = 25mA
I_LOAD = 50mA
5.002
5.000
4.998
4.996
If large load currents are used, then the user must connect the
voltage meter as close as possible to the output capacitor to
reduce the effects of IR drops.
4.994
4.992
4.990
0
5
10
15
20
25
30
V_IN (V)
Figure 6. ADP1720 Line Regulation
Rev. 0 | Page 5 of 8