Analog Devices ADP2105 Evaluation Board ADP2105-EVALZ ADP2105-EVALZ Datenbogen
Produktcode
ADP2105-EVALZ
EVAL-ADP2105
Rev. 0 | Page 3 of 12
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2105 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures outlined in this section.
tested. Before applying power to the evaluation board, follow
the procedures outlined in this section.
Jumper J1
Before turning on the ADP2105 evaluation board, make sure
that all the components are present, but that Jumper J1 is removed.
that all the components are present, but that Jumper J1 is removed.
Input Power Source
Before connecting the power source to the ADP2105 evaluation
board, make sure 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
board, make sure 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
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 ADP2105 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 the board is turned off before con-
necting 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
connection of the load, it is possible to damage the load if it is not
properly connected. Make sure the board is turned off before con-
necting 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 connection 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
is used, connect it in series with the load: connect the positive (+)
ammeter terminal to the evaluation board V
OUT
terminal, the nega-
tive (−) ammeter terminal to the positive (+) load terminal, and the
negative (−) load terminal to the evaluation board GND terminal.
negative (−) load terminal to the evaluation board GND terminal.
Once the load is connected, make sure it is set to the proper
current before powering the ADP2105 evaluation board.
current before powering the ADP2105 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 would be incorrect due
to the voltage drop across the leads and/or connections between
the evaluation board, the power source, and/or the load.
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 would be 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
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
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 ADP2105
evaluation board, the board 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 ADP2105-1.8-EVAL and
2.5 V for the ADP2105-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.
evaluation board, the board 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 ADP2105-1.8-EVAL and
2.5 V for the ADP2105-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.
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 is
small (<20 mV), but in PFM mode, the output voltage ripple
can be as large as 50 mV.
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 oscilloscope to dc, 2 V/division, and 2 μs/division time base.
The switching waveform must alternate between 0 V and
approximately the input voltage.
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 oscilloscope to dc, 2 V/division, and 2 μs/division time base.
The switching waveform must alternate between 0 V and
approximately the input voltage.
Measuring Load Regulation
The 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.
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.
voltage.
Measuring Efficiency
The efficiency, η, is measured by comparing the input power
with the output power.
with the output power.
IN
IN
OUT
OUT
I
V
I
V
×
×
=
η
Measure the input and output voltages as close as possible to the
input and output capacitors to reduce the effect of IR drops.
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.
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.