Datasheet

VIN

UVLO

OTP

RAMP

TIME3

REF

TIME1

TIME2

RES

SSSR

COMP

OUTA

OUTB

OUTSR

AGND

PGND

VCC

ERROR AMP and

ISOLATION

VOUT

VIN

LM5027

Schematic

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3 Schematic

Figure 1. Board Schematic

4 Powering and Loading Considerations

When applying power to the LM5027 evaluation board certain precautions need to be followed. A failure or

mis-connection can present itself in a very alarming manner.

4.1 Proper Connections

When operated at low input voltages the evaluation board can draw up to 3.5A of current at full load. The

maximum rated output current is 30A. Be sure to choose the correct connector and wire size when

attaching the source supply and the load. Monitor the current into and out of the evaluation board. Monitor

the voltage directly at the output terminals of the evaluation board. The voltage drop across the load

connecting wires will give inaccurate measurements; this is especially true for accurate efficiency

measurements.

4.2 Source Power

The evaluation board can be viewed as a constant power load. At low input line voltage (36V) the input

current can reach 3.5A, while at high input line voltage (78V) the input current will be approximately 1.5A.

Therefore too fully test the LM5027 evaluation board a DC power supply capable of at least 80V and 4A is

required. The power supply must have adjustments for both voltage and current. An accurate readout of

output current is desirable since the current is not subject to loss in the cables as voltage is. The power

AN-1976 LM5027 Evaluation Board SNVA400B–August 2009–Revised May 2013

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