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Test Procedure

7.2 Control Loop Gain and Phase Measurement Procedure

TPS53317EVM-750 contains a 10-Ω series resistor in the feedback loop for loop response analysis.

1. Set up EVM as described in Figure 3.

2. Connect isolation transformer to test points marked TP12 and TP13.

3. Connect input signal amplitude measurement probe (channel A) to TP12. Connect output signal

amplitude measurement probe (channel B) to TP13.

4. Connect ground lead of channel A and channel B to TP14.

5. Inject around 40 mV or less signal through the isolation transformer.

6. Sweep the frequency from 500 Hz to 500 kHz with 10 Hz or lower post filter. The control loop gain and

phase margin can be measured.

7. Disconnect isolation transformer from bode plot test points before making other measurements (signal

injection into feedback may interfere with accuracy of other measurements).

7.3 List of Test Points

Table 6. The Functions of Each Test Points

TEST POINTS NAME DESCRIPTION

TP1 VIN Input voltage

TP2 PGND PGND for VIN

5-V power supply for analog circuits and

TP3 V5IN

gate drive

TP4 PGND PGND for V5IN

TP5 VOUT Output voltage

TP6 PGND PGND for VOUT

TP7 PGOOD Power good

TP8 EN Enable pin

TP9 SW Switching node

TP10 AGND Signal ground

TP11 VREF Internal 2-V reference voltage output

TP12 CHA Input A for loop injection

TP13 CHB Input B for loop injection

TP14 AGND Signal ground

TP15 REFIN Target output voltage input

7.4 Equipment Shutdown

1. Shut down VIN

2. Shut down V5IN

3. Shut down Load

4. Shut down FAN

SLUU642–September 2011 TPS53317EVM-750 D-CAP+™ Mode Synchronous Step-Down Integrated FETs

Converter

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