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Getting Started

4 Getting Started

Preset the power supply to 5 V and turn off. Connect the power supply output to the input terminals of the

HPA424. Remove jumper J2.

Slide S1 and S2 to disable the TPS2556 or TPS2557. Turn on the power supply to apply 5.0 V to the EVM

input-power terminals. VOUT1 should be 0 V.

Slide S2 to enable the device. For TPS2556, set S1 to LO; for TPS2557, set S1 to HI. VOUT1 should be

VIN + / - 0.3 V.

Set the oscilloscope to auto trigger mode and the horizontal-sweep to 4 ms/div. Set all vertical channels

for 2 V/div except the current probe set for 500 mA/div.

4.1 Monitor

1. Input voltage at TP1

2. Output voltage at TP12

3. EVM input current

4. FAULT# status voltage at test point TP11

4.2 Verify EVM Output

1. Set the scope for normal trigger, single sweep. Trigger on VOUT1, negative slope at about a 3.5-V

level.

2. Momentarily short the output connector. A sample scope trace is shown in Figure 2. Observe VOUT1

drops to 0 V.

3. Input current rises to an amplitude of 1.25 A + / - 0.25 A, within 0 to 4 ms after VOUT low.

4. FAULT1 signal is low 2 ms to 20 ms after VOUT low.

5 Performance Data and Typical Characteristics Curves

VOUT2 can be verified the same way as VOUT1.

Figure 2. 100-kΩ R

ILIM

Enabled into a Short Circuit

SLUU394–November 2009 Using the TPS2560EVM-424 and TPS2561EVM-424

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