Datasheet

UG-056 Evaluation Board User Guide
Rev. B | Page 10 of 12
Figure 13, Figure 14, and Figure 15 show how the evaluation
boards can be connected to a voltage source and an ammeter
for ground current measurements. A resistor can be used as the
load for the regulator. Ensure that the resistor has a power
rating that is adequate to handle the power that is expected to
dissipate across it. An electronic load can be used as an
alternative. Ensure that the voltage source can supply enough
current for the expected load levels.
Follow these steps to connect to a voltage source and ammeter:
1. Connect the positive terminal (+) of the voltage source to
the VIN pad of the evaluation board.
2. Connect the positive terminal (+) of the ammeter to one
of the GND pads on the evaluation board.
3. Connect the negative terminal (−) of the ammeter to the
negative (−) terminal of the voltage source.
4. Connect a load between the VOUT pad of the evaluation
board and the negative (−) terminal of the voltage source.
5. If the ADP124 LFCSP board is being used, short R1.
Otherwise, install R1 and R2 for the ADP125 adjustable
LDO.
When these steps are completed, the voltage source can be turned
on. If J1 is inserted (connecting EN to VIN for automatic startup),
the regulator powers up.
GROUND CURRENT CONSUMPTION
Ground current measurements can determine how much current
the internal circuits of the regulator consume while the circuits
perform the regulation function. To be efficient, the regulator
must consume as little current as possible. Typically, the regulator
uses the maximum current when supplying its largest load level
(500 mA). Figure 16 shows the typical ground current consumption
for various load levels at V
OUT
= 3.3 V and T
A
= 25°C.
When the device is disabled (EN = GND), the ground current
drops to less than 1 μA.
50
70
90
110
130
150
170
190
210
230
250
3.50 4.00 4.50 5.00 5.50
V
IN
(V)
GROUND CURRENT (µA)
I
OUT
= 100µA
I
OUT
= 1mA
I
OUT
= 10mA
I
OUT
= 100mA
I
OUT
= 300mA
I
OUT
= 500mA
08525-012
Figure 16. Ground Current vs. Input Voltage (V
IN
) at V
OUT
= 3.3 V, T
A
= 25°C