Evaluation Board User Guide UG-270
Rev. 0 | Page 3 of 8
USING THE EVALUATION BOARD
POWERING UP THE EVALUATION BOARD
The ADP2147 evaluation board is supplied fully assembled and
tested. Before applying power to the evaluation board, follow
the procedures in this section.
Jumper JP3 (ENABLE)
Jumper JP3 (EN) enables/disables the ADP2147. Connect a
jumper between Pin 2 of JP3 and Pin 3 (VIN) of JP3, to enable
the ADP2147. Connecting Pin 2 of JP3 to Pin 1 of JP3 disables
the ADP2147 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 (VIN) on the evaluation board, and the
negative terminal of the power source to TB5 (GND IN) 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
TB5 (GND IN) on the evaluation board, and the negative (−)
lead of the ammeter to TB1 (VIN) on the evaluation 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,
connect the load directly to the evaluation board, with the
positive (+) load connection to TB3 (VOUT) and the negative
(−) load connection 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 at TB3
(VOUT), the negative (−) ammeter terminal to the positive (+)
load terminal, and the negative (−) load terminal to the evaluation
board at 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 evaluation
board terminals and not to the load or power sources 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 at TB1 (VIN), and the negative
(−) terminal to the evaluation board at TB5 (GND IN). Connect
the output voltage measuring voltmeter positive (+) terminal to
the evaluation board at TB3 (VOUT) and the negative (−) terminal
to the evaluation board at TB4 (GND OUT).
Turning On the Evaluation Board
After the power source and load are connected to the ADP2147
evaluation board, the board can be powered for operation. To
do this, perform the following steps:
1. Ensure that the power source voltage is >2.3 V but <5.5 V.
2. Ensure that JP3 (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.
Changing the Output Voltage of the Device
Each ADP2147 has a VSELpin, which determines the output
voltage of the buck regulator by either a high selection (the
VSEL pin is set high by connecting Pin 2 of JP2 to Pin 3 of JP2)
or by a low selection (the VSEL pin is set low by connecting Pin
2 of JP2 to Pin 1 of JP2).
MEASURING EVALUATION BOARD PERFORMANCE
Measuring Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope probe
across the output capacitor (COUT) 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.
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.
Measuring Load Regulation
The load regulation is 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 loads
approaching maximum current.
Measuring Line Regulation
Vary the input voltage and examine the change in the output
voltage.
Measuring Efficiency
Measure the efficiency, η, 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. A
current probe can be connected onto this wire.
