LM5035CEVAL/NOPB National Semiconductor, LM5035CEVAL/NOPB Datasheet - Page 2

• Manufacturer Part Number: LM5035CEVAL/NOPB
• Description: EVAL BOARD FOR LM5035C
• Manufacturer: National Semiconductor

Specifications of LM5035CEVAL/NOPB

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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Powering and Loading
Considerations
When applying power to the LM5035C evaluation board cer-
tain precautions need to be followed. A misconnection can
damage the assembly.
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. Mon-
itor the voltage directly at the output terminals of the evalua-
tion board. The voltage drop across the load connecting wires
will cause inaccurate measurements. This is especially true
for accurate efficiency measurements.
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 (75V) the input
current will be approximately 1.5A. Therefore, to fully test the
LM5035C evaluation board a DC power supply capable of at
least 85V and 5A is required.
The power supply must have adjustments for both voltage
and current. The power supply and cabling must present low
impedance to the evaluation board. Insufficient cabling or a
high impedance power supply will cause voltage droop during
turn-on due to the evaluation board inrush current. If large
enough, this droop will cause a chattering condition upon
power up. This chattering condition is an interaction with the
Simplified Half Bridge Converter
2
evaluation
impedance and the inrush current.
Loading
An appropriate electronic load, with specified operation down
to 1.0V minimum, is desirable. The resistance of a maximum
load is 0.11Ω. The high output current requires thick cables!
If resistor banks are used there are certain precautions to be
taken. The wattage and current ratings must be adequate for
a 30A, 100W supply. Monitor both current and voltage at all
times. Ensure there is sufficient cooling provided for the load.
Air Flow
Full power loading should never be attempted without pro-
viding the specified 200 CFM of air flow over the evaluation
board. A stand-alone fan should be provided.
Powering Up
Using the ON/OFF pin (J2) provided will allow powering up
the source supply with the current level set low. It is suggested
that the load be kept low during the first power up. Set the
current limit of the source supply to provide about 1.5 times
the wattage of the load. As you remove the connection from
the ON/OFF pin to ground (J1), immediately check for 3.3
volts at the output.
A most common occurrence, that will prove unnerving, is
when the current limit set on the source supply is insufficient
for the load. The result is similar to having the high source
impedance referred to earlier. The interaction of the source
supply folding back and the evaluation board going into un-
dervoltage shutdown will start an oscillation, or chatter, that
may have undesirable consequences.
board
undervoltage
lockout,
the
30119501
cabling