Datasheet

EVAL-ADP220/ADP221
Rev. 0 | Page 6 of 8
GROUND CURRENT MEASUREMENTS
07575-007
+–
VOLTAGE SOURCE
+–
AMMETER
0.00049
LOAD
LOAD
Figure 7. Ground Current Measurement
Figure 7 shows how the evaluation board can be connected to
a voltage source and an ammeter for ground current measure-
ments. A resistor can be used as the load for the regulator.
Ensure that the resistor has a power rating adequate to handle
the power expected to be dissipated across it. An electronic load
can be used as an alternative. Ensure that the voltage source used
can supply enough current for the expected load levels.
Use the following steps to connect to a voltage source and ammeter:
1. Connect the positive terminal (+) of the voltage source to
the VIN pad on the evaluation board.
2. Connect the positive terminal (+) of the ammeter to one of
the GND pads of the evaluation board.
3. Connect the negative terminal (−) of the ammeter to the
negative (−) terminal of the voltage source.
4. Connect a load between VOUT1 and/or VOUT2 of the
evaluation board and the negative (−) terminal of the
voltage source.
The voltage source can now be turned on. If J1 or J2 is inserted
(connecting EN1 or EN2 to VIN for automatic startup), the
regulator powers up.
GROUND CURRENT CONSUMPTION
Ground current measurements can determine how much current
the regulator’s internal circuits are consuming while the circuits
perform the regulation function. To be efficient, the regulator
needs to consume as little current as possible. Typically, the regu-
lator uses the maximum current when supplying its largest load
level (200 mA per output). Figure 8 shows the typical ground
current consumption for various load levels at an input voltage
of 3.3 V for a single output.
When the device is disabled (EN1 and EN2 = GND), ground
current drops to less than 1 μA.
0
20
40
60
80
100
120
140
0.01 0.1 1 10 100 1k
LOAD CURRENT (mA)
GROUND CUR
R
ENT (u
A
)
07575-008
V
OUT
= 2.8V
V
IN
= 3.3V
SINGLE OUTPUT
BOTH OUTPUTS
Figure 8. Ground Current vs. Load Current