Datasheet

EVAL-ADP2106
Rev. 0 | Page 3 of 12
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2106 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures outlined in this section.
Jumper J1
Before turning on the ADP2106 evaluation board, make sure that
all the components are present, but that Jumper J1 is removed.
Input Power Source
Before connecting the power source to the ADP2106 evaluation
board, make sure that it is turned off. If the input power source
includes a current meter, use that meter to monitor the input
current. Connect the positive terminal of the power source to the
V
IN
terminal on the evaluation board, and the negative terminal of
the power source to the GND terminal of the evaluation board. If
the power source does not include a current meter, connect a
current meter in series with the input source voltage. Connect
the positive lead (+) of the power source to the ammeter positive
(+) connection, the negative lead (−) of the power source to the
GND terminal on the evaluation board, and the negative lead (−) of
the ammeter to the V
IN
terminal on the board.
Output Load
Although the ADP2106 evaluation board can sustain the
sudden connection of the load, it is possible to damage the load
if it is not properly connected. Make sure that the board is
turned off before connecting the load. If the load includes an
ammeter, or if the current is not measured, connect the load
directly to the evaluation board with the positive (+) load
connection to the V
OUT
terminal and the negative (−) load connec-
tion to the GND terminal. If an ammeter is used, connect it in
series with the load; connect the positive (+) ammeter terminal to
the evaluation board V
OUT
terminal, the negative (−) ammeter
terminal to the positive (+) load terminal, and the negative (−) load
terminal to the evaluation board GND terminal. Once the load is
connected, make sure that it is set to the proper current before
powering the ADP2106 evaluation board.
Input and Output Voltmeters
Measure the input and output voltages with voltmeters. Make
sure that the voltmeters are connected to the appropriate
evaluation board terminals and not to the load or power source
themselves. If the voltmeters are not connected directly to the
evaluation board, the measured voltages are incorrect due to the
voltage drop across the leads and/or connections between the
evaluation board, the power source, and/or the load.
Connect the input voltage measuring voltmeter positive
terminal (+) to the evaluation board V
IN
terminal and the
negative (−) terminal to the evaluation board GND terminal.
Connect the output voltage measuring voltmeter positive (+)
terminal to the evaluation board V
OUT
terminal and the negative
(−) terminal to the evaluation board GND terminal.
Turning On the Evaluation Board
Once the power source and load are connected to the
ADP2106 evaluation board, it can be powered for operation.
Slowly increase the input power source voltage until the input
voltage exceeds the minimum input operating voltage of 2.7 V.
Insert Jumper J1 and check to see if the output voltage rises to
the regulated output voltage (1.8 V for the ADP2106-1.8-EVAL
and 2.5 V for the ADP2106-EVAL). If the load is not already
enabled, enable the load, and check that it is drawing the proper
current and that the output voltage maintains voltage regulation.
MEASURING EVALUATION BOARD PERFORMANCE
Measuring Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope
probe across the output capacitor (C3/C4) with the probe
ground lead at the negative (−) capacitor terminal and the
probe tip at the positive (+) capacitor terminal. Set the
oscilloscope to ac, 20 mV/division, and 2 μs/division time base.
In the PWM mode of operation, the output voltage ripple must
be small (<20 mV), but in PFM mode, the output voltage ripple
can be as large as 50 mV.
Measuring the Switching Waveform
To observe the switching waveform with an oscilloscope, place
the oscilloscope probe tip at the end of the inductor that is
connected to the LX pins with the probe ground at GND.
Set the scope to dc, 2 V/division, and 2 μs/division time base.
The switching waveform should alternate between 0 V and the
approximate input voltage.
Measuring Load Regulation
Load regulation must be tested by increasing the load at the output
and looking at the change in output voltage. To minimize voltage
drop, use short low resistance wires, especially for heavy loads.
Measuring Line Regulation
Vary the input voltage and examine the change in the output
voltage.
Measuring Efficiency
The efficiency, η, is measured by comparing the input power
with the output power.
ININ
OUTOUT
IV
IV
×
×
= η
Measure the input and output voltages as close as possible to the
input and output capacitors to reduce the effect of IR drops.
Measuring Inductor Current
The inductor current can be measured by removing one end of
the inductor from its pad and connecting a current loop in
series with it. Then a current probe can be used to measure the
current flowing through the current loop, as shown in Figure 2.