Evaluation Board User Guide UG-229
Rev. 0 | Page 5 of 8
GROUND CURRENT MEASUREMENT
Figure 6 shows how the evaluation board 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 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. If voltmeters
are connected at the input or output terminals, subtract the
current resulting from the shunt resistance of the voltmeter
for accurate ground current measurement.
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 the
GND pad 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 the VOUT pad of the evaluation
board and the negative (−) terminal of the voltage source.
The voltage source can now be turned on. If J2 is inserted
(connecting EN to VIN for automatic startup), the regulator
powers up.
GROUND CURRENT CONSUMPTION
Ground current measurement is a way of determining how
much current the internal circuits of the regulator are consum-
ing while performing the power switch function. To be efficient,
the power switch must consume as little current as possible.
Figure 5 shows the typical ground current consumption for
various load levels.
0
1
2
3
4
5
6
7
1.0 1.4
1.8 2.2 2.6 3.0 3.4
GROUND CURRENT (µA)
V
IN
(V)
I
LOAD
= 10mA
I
LOAD
= 20mA
I
LOAD
= 50mA
I
LOAD
= 100mA
I
LOAD
= 200mA
I
LOAD
= 500mA
09561-005
Figure 5. Ground Current vs. Input Voltage, V
IN
VOLTAGE SOURCE
LOAD
AMMETER
0.00112
09561-006
Figure 6. Ground Current Measurement
