Efficiency Measurement Test Points; Figure 7-2. Efficiency - Texas Instruments TPS546B24AEVM-2PH User Manual

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6.2 Efficiency Measurement Test Points

To evaluate the efficiency of the power train (device and inductor), it is important to measure the voltages at
the correct location. This is necessary because otherwise the measurements will include losses that are not
related to the power train itself. Losses incurred by the voltage drop in the copper traces and in the input and
output connectors are not related to the efficiency of the power train, which should not be included in efficiency
measurements.
Input current can be measured at any point in the input wires, and output current can be measured anywhere in
the output wires of the output being measured.
Table 6-1 shows the measurement points for input voltage and output voltage. VIN and VOUT are measured
to calculate the efficiency. Using these measurement points will result in efficiency measurements that excluded
losses due to the wires and connectors.
Test Point Node Name Description
Input voltage measurement point
TP12 PVIN
for VIN+
Input voltage measurement point
TP15 PGND
for VIN– (GND)
Output voltage measurement
TP22 VOUT
point for VOUT+
Output voltage measurement
TP25 GND
point for VOUT– (GND)
For more accurate efficiency measurements of the power train, the voltage drop between the power train and the
terminals should also be removed from the measurement. Using the test points in
losses. To average the voltages at each test point so that only one meter is needed for PVIN and VOUT, add
some resistance between the each test point and the meter. For the measurements taken in this user's guide, a
1.5-kΩ resistor was added in series with each test point. Using these test points reduced the measured power
loss at 40 A load by approximately 0.15 W. This power is lost in the copper traces of the PCB.
Test Point Node Name Description
Input voltage measurement point
TP1_P1 PVIN_P1
for VIN+
Input voltage measurement point
TP4_P1 GND_P1
for VIN– (PGND)
Input voltage measurement point
TP1_P2 PVIN_P2
for VIN+
Input voltage measurement point
TP4_P2 GND_P2
for VIN– (PGND)
Output voltage measurement
TP13 VOUT_P1
point for VOUT+
Output voltage measurement
TP16 GND_P1
point for VOUT– (GND)
Output voltage measurement
TP26 VOUT_P2
point for VOUT+
Output voltage measurement
TP30 GND_P2
point for VOUT– (GND)
SLUUC48A – FEBRUARY 2020 – REVISED FEBRUARY 2022
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Table 6-1. Test Points for Efficiency Measurements
Comment
The pair of test points is connected to the PVIN/PGND pins of U1_P1. The voltage drop
between input terminal to the device pins is included for efficiency measurement.
The pair of test points is connected near the output terminals. The voltage drop from the
output point of the inductor to the output terminals is included for efficiency measurement.
Table 6-2. Test Points for Better Efficiency Measurements
Comment
This pair of test points is connected to PVIN and PGND near the pins of U1_P1.
This pair of test points is connected to PVIN and PGND near the pins of U1_P2.
This pair of test points is connected to VOUT and GND near the output inductor for U1_P1.
This pair of test points is connected to VOUT and GND near the output inductor for U1_P2.
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TPS546B24A 2-Phase SWIFT™ Step-Down Converter Evaluation Module
Test Procedure
Table 6-2 will reduce these
User's Guide
15