7 Test Point Descriptions
Table 7-1. Test Point Descriptions
TEST POINT
LABEL
DESCRIPTION
TP1
VIN
Measurement test point for input voltage
TP2
GND
Ground test point for input voltage
TP3
VOUT
Measurement test point for output voltage
TP4
GND
Ground test point for output voltage
TP5
EN/SS
Measurement test point for enable/soft-start
TP6
PGOOD
Measurement test point for power good
TP7
CHA
Measurement test point for channel A of loop response
TP8
SGND
Ground test point for channel A of loop response
TP9
SGND
Ground test point for channel B of loop response
TP10
CHB
Measurement test point for channel B of loop response
TP11
SW
Measurement test point for switch node voltage
TP12
GND
Ground test point for switch node voltage
7.1 Input Voltage Monitoring (TP1 and TP2)
TPS56121EVM-601 provides two test points for measuring the input voltage applied to the module. This allows
the user to measure the actual input module voltage without losses from input cables and connectors. To use
TP1 and TP2, connect a voltmeter positive input terminal to TP1 and negative input terminal to TP2.
7.2 Output Voltage Monitoring (TP3 and TP4)
TPS56121EVM-601 provides two test points for measuring the output voltage generated by the module. To use
TP3 and TP4, connect a voltmeter positive input terminal to TP3 and negative input terminal to TP4. For output
ripple monitoring, please refer to the tip and barrel measurement technique in
.
7.3 Enable/Soft-start Monitoring (TP5)
TPS56121EVM-601 provides a test point for measuring the enable/soft-start voltage of the TPS56121 converter.
This test point can be monitored to observe the start-up calibration waveform, soft-start ramp or fault time-out
timing.
The enable/soft-start test point should not be actively driven from an external circuit, such as a logic output of
another power supply.
7.4 Power Good Monitoring (TP6)
TPS56121EVM-601 provides a test points for measuring the Power Good voltage of the TPS56121 converter.
7.5 Loop Response Testing (TP7, TP8, TP9 and TP10)
TPS56121EVM-601 provides four test points (two signals and two grounds) for measuring the control loop
frequency response. This allows the user to measure the actual module loop response without modifying the
evaluation board. See
for additional detail.
7.6 Switch Node Voltage Monitoring (TP11 and TP12)
TPS56121EVM-601 provides two test points for measuring the switch node. To monitor the switch node voltage,
set oscilloscope per Oscilloscope For Switching Waveforms in
. Connect the oscilloscope probe to
TP11 and the ground lead of the probe to TP12. To monitor the voltage spike on switch node, please remove
the bandwidth limit on the oscilloscope and refer to the Application Report SLPA005 (Reducing Ringing Through
PCB Layout Techniques) for the measurement techniques.
Test Point Descriptions
10
TPS56121 Step-Down Converter Evaluation Module User's Guide
SLVU445C – MARCH 2011 – REVISED AUGUST 2021
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