Datasheet

UG-407 ADP2441-EVALZ User Guide
Rev. 0 | Page 4 of 12
MEASURING EVALUATION BOARD
PERFORMANCE
Output Voltage Ripple
To observe the output voltage ripple, place an oscilloscope
probe tip at Terminal T3 and connect the probe ground lead at
the negative (−) Terminal T4. Set the oscilloscope to an ac-
coupled, 100 mV/division and 2 μs/division time base.
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 SW pin with the probe ground at Terminal T4,
GND. Set the scope to dc, 5 V/division, and 2 µs/division time
base. The switching waveform should alternate between 0 V
and approximately the input voltage.
Figure 4. Switch Node Measurement
Measuring Load Regulation
The load regulation should be measured 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. In PWM mode, the output voltage ripple should be
small (<50 mV) but in pulse skip mode, the output voltage
ripple can be as large as 100 m V.
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.
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.
Line Transient Response
Generate a step input voltage (V
IN
) and observe the behavior
of the output voltage, with an oscilloscope.
Load Transient Response
Generate a load current transient at the output, V
OUT
, and
observe the output voltage response with an oscilloscope.
Use a current probe attached to the wire between the output
and the load to visualize the current transient.
Loop Stability Measurement
Closed-loop response can be measured using a network
analyzer. To measure the loop response, Header IN and
Header OUT are available.
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