Datasheet

0-36V, 11A

DC Power

Supply

Scope

VIN+

VIN-

VOUT-

VOUT+

LM25117 BUCK

Current-meter

+ Electronic Load

With Current Meter

- 0A-9A

Volt-meter Volt-meter

Powering and Loading Consideration

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3.3 Loading

When using an electronic load, it is strongly recommended to power up the evaluation board at light load

and then slowly increase the load. If it is desired to power up the evaluation board at maximum load,

resistor bank must be used. In general, electronic load is best suited for monitoring steady state

waveforms.

3.4 Air Flow

Prolonged operation with high input voltage at full power will cause the MOSFETs to overheat. A fan with

a minimum of 200LFM should be always provided.

3.4.1 Quick Start-up Procedure

1. Set the power supply current limit to at least 11A. Connect the power supply to J1 and J2.

2. Connect the load with a 9A capacity between J3 and J4.

3. Set input voltage to 6V and turn it on.

4. Measure the output voltage. The output should be regulated at 3.3V.

5. Slowly increase the load current while monitoring the output voltage. The output should remain in

regulation up to full load current.

6. Slowly sweep the input voltage from 6V to 36V while monitoring the output voltage. The output should

remain in regulation.

Figure 1. Typical Evaluation Setup

3.5 Waveforms

3.5.1 Soft Start

When applying power to the LM25117 evaluation board a certain sequence of events occurs. Soft-start

capacitor and other components allow for a linear increase in output voltage. Figure 2 shows the output

voltage during a typical start-up with a load of 0.5Ω

AN-2112 LM25117 Evaluation Board SNVA469B–May 2011–Revised April 2013

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