UG-879 ADP5300-EVALZ Evaluation Board User Guide
Rev. 0 | Page 4 of 7
MEASURING EVALUATION BOARD PERFORMANCE
Measuring the Switching Waveform
To observe the switching waveform with an oscilloscope, place
the oscilloscope probe tip at TP2, and ensure that the probe
ground is connected to GND at TP5. Set the oscilloscope to a dc
coupling, 2 V/division, 1 µs/division time base. The switching
waveform must alternate between 0 V and the approximate
input voltage.
Measuring Load Regulation
Test load regulation by increasing the load at the output and
measuring the output voltage between the TP4 and TP7 test
points.
Measuring Line Regulation
Vary the input voltage and measure the output voltage at a fixed
output current. Measure the input voltage between TP1 and TP5.
The output voltage is measured between TP4 and TP7.
Measuring Efficiency
Measure the efficiency, η, by comparing the input power with
the output power.
ININ
OUTOUT
IV
IV
η
×
×
=
Measuring Inductor Current
Measure the inductor current by removing one end of the
inductor from the pad on the ADP5300-EVA L Z and using a
wire connected between the pad and the inductor. Then, use a
current probe to measure the inductor current.
Measuring Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope probe
across the C2 output capacitor, with the probe ground lead placed
at the negative capacitor terminal (−) and the probe tip placed
at the positive capacitor terminal (+). Set the oscilloscope to an
ac coupling, 10 mV/division, 2 µs/division time base and a
20 MHz bandwidth.
A standard oscilloscope probe has a long wire ground clip. For
high frequency measurements, this ground clip picks up high
frequency noise and injects it into the measured output ripple.
Figure 2 shows how to measure the output ripple. Measuring
the output ripple requires removing the oscilloscope probe
sheath and wrapping an unshielded wire around the oscilloscope
probe. By keeping the ground lengths of the oscilloscope probe
as short as possible, true ripple can be measured.
Figure 2. Output Ripple Measurement
Output Voltage Change
The output voltage of the evaluation board is preset to 1.8 V.
However, the output voltage can be adjusted with an external
VID resistor (see the ADP5300 data sheet).
