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Test Procedure

5.4 Enable Selection

The controller can be enabled and disabled by J2.

Default setting: Jumper shorts on J2 to disable the controller

Table 5. Enable Selection

Jumper Set to Enable Selection

Jumper shorts on J2 Disable the controller

No jumper shorts on J2 Enable the controller

6 Test Procedure

6.1 Line/Load Regulation and Efficiency Measurement Procedure

1. Set up EVM as described in Section 4 and Figure 3.

2. Ensure Load is set to constant resistance mode and to sink 0 Adc.

3. Ensure that all jumpers configuration settings are per Section 5.

4. Ensure that the jumper provided in the EVM shorts on J2 before Vin is applied.

5. Increase V

from 0 V to 12 V. Use V1 to measure input voltage.

6. Remove the jumper on J2 to enable the controller.

7. Use V2 to measure VOUT voltage

8. Vary Load from 0 Adc to 30 Adc; Vout must remain in load regulation.

9. Vary V

from 8 V to 14 V; Vout must remain in line regulation.

10. Put the jumper on J2 to disable the controller.

11. Decrease Load to 0 A

12. Decrease V

to 0 V.

6.2 Control Loop Gain and Phase Measurement Procedure

TPS53355EVM-743 contains a 10-Ω series resistor in the feedback loop for loop response analysis.

1. Set up the EVM as described in Section 4 and Figure 3.

2. Connect isolation transformer to test points marked TP10 and TP11.

3. Connect input signal amplitude measurement probe (channel A) to TP10. Connect output signal

amplitude measurement probe (channel B) to TP11.

4. Connect ground lead of channel A and channel B to TP12.

5. Inject an approximate 40-mV or less signal through the isolation transformer.

6. Sweep the frequency from 100 Hz to 1 MHz 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.)

SLUU522–August 2011 Using the TPS53355EVM-743, High-Efficiency, 30-A, Synchronous Buck

Converter With Eco-mode™— Control Scheme

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