Analog Devices ADP2108 Evaluation Board ADP2108-3.0-EVALZ ADP2108-3.0-EVALZ Datenbogen
Produktcode
ADP2108-3.0-EVALZ
EVAL-ADP2108
Rev. A | Page 3 of 8
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2108 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures in this section.
tested. Before applying power to the evaluation board, follow
the procedures in this section.
Jumper TB2 (Enable)
Jumper TB2 (EN) enables/disables the ADP2108. Connect a
jumper between TB2 and TB1 (V
jumper between TB2 and TB1 (V
IN
) to enable the ADP2108.
Connecting TB2 (EN) to TB4 (GND OUT) disables the
ADP2108 and brings the current to < 1 μA.
ADP2108 and brings the current to < 1 μA.
Input Power Source
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 TB1 (V
to monitor the input current. Connect the positive terminal of the
power source to TB1 (V
IN
) on the evaluation board, and the nega-
tive terminal of the power source to TB4 (GND OUT) of the
evaluation board.
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 TB4 (GND
OUT) on the evaluation board, and the negative lead (−) of the
ammeter to TB1 (V
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 TB4 (GND
OUT) on the evaluation board, and the negative lead (−) of the
ammeter to TB1 (V
IN
) on the board.
Output Load
Connect an electronic load or resistor to set the load current. If the
load includes an ammeter, or if the current is not measured, con-
nect the load directly to the evaluation board, with the positive (+)
load connection to TB3 (V
load includes an ammeter, or if the current is not measured, con-
nect the load directly to the evaluation board, with the positive (+)
load connection to TB3 (V
OUT
) and the negative (−) load connec-
tion to TB4 (GND OUT).
If an ammeter is used, connect it in series with the load. Connect
the positive (+) ammeter terminal to the evaluation board TB3
(V
the positive (+) ammeter terminal to the evaluation board TB3
(V
OUT
), the negative (−) ammeter terminal to the positive (+) load
terminal, and the negative (−) load terminal to the evaluation
board TB4 (GND OUT).
board TB4 (GND OUT).
Input and Output Voltmeters
Measure the input and output voltages with voltmeters. Make
sure that the voltmeters are connected to the appropriate eval-
uation 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.
sure that the voltmeters are connected to the appropriate eval-
uation 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 termi-
nal (+) to the evaluation board TB1 (V
nal (+) to the evaluation board TB1 (V
IN
), and the negative (−)
terminal to the evaluation board TB4 (GND OUT). Connect the
output voltage measuring voltmeter positive (+) terminal to the
evaluation board TB3 (V
output voltage measuring voltmeter positive (+) terminal to the
evaluation board TB3 (V
OUT
) and the negative (−) terminal to the
evaluation board TB4 (GND OUT).
Turning On the Evaluation Board
Once the power source and load are connected to the ADP2108
evaluation board, the board can be powered for operation.
Perform the following steps:
evaluation board, the board can be powered for operation.
Perform the following steps:
1. Ensure that the power source voltage is > 2.3 V and < 5.5 V.
2. Ensure that TB2 (EN) is high and monitor the output voltage.
If the load is not already enabled, enable the load, check that it is
drawing the proper current, and that the output voltage maintains
voltage regulation.
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 (C
across the output capacitor (C
OUT
) 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.
(+) capacitor terminal. Set the oscilloscope to ac, 20 mV/division,
and 2 μs/division time base.
Measuring the Switching Waveform
To observe the switching waveform with an oscilloscope, place
the oscilloscope probe tip at the end of the inductor with the probe
ground at GND OUT. Set the oscilloscope to dc, 2 V/division, and
2 μs/division time base.
the oscilloscope probe tip at the end of the inductor with the probe
ground at GND OUT. Set the oscilloscope to dc, 2 V/division, and
2 μs/division time base.
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 mini-
mize voltage drop, use short low resistance wires, especially for
loads approaching maximum current.
output and looking at the change in output voltage. To mini-
mize voltage drop, use short low resistance wires, especially for
loads approaching maximum current.
Measuring Line Regulation
Vary the input voltage and examine the change in the output
voltage.
voltage.
Measuring Efficiency
Measure the efficiency, η, by comparing the input power with
the output power.
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. A current probe can be connected onto this wire.
of the inductor from its pad and connecting a current loop in
series. A current probe can be connected onto this wire.