Texas Instruments Evaluation Board for the LM5035C LM5035CEVAL/NOPB LM5035CEVAL/NOPB データシート
製品コード
LM5035CEVAL/NOPB
Source Power
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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.
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 evaluation board undervoltage lockout, the cabling impedance and the inrush current.
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 evaluation board undervoltage lockout, the cabling impedance and the inrush current.
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Loading
An appropriate electronic load, with specified operation down to 1.0V minimum, is desirable. The
resistance of a maximum load is 0.11
resistance of a maximum load is 0.11
Ω
. 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.
30A, 100W supply. Monitor both current and voltage at all times. Ensure there is sufficient cooling
provided for the load.
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Air Flow
Full power loading should never be attempted without providing the specified 200 CFM of air flow over the
evaluation board. A stand-alone fan should be provided.
evaluation board. A stand-alone fan should be provided.
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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.
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 undervoltage shutdown
will start an oscillation, or chatter, that may have undesirable consequences.
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 undervoltage shutdown
will start an oscillation, or chatter, that may have undesirable consequences.
A quick efficiency check is the best way to confirm that everything is operating properly. If something is
amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be
incorrect in a switching power supply without creating losses and potentially damaging heat.
amiss you can be reasonably sure that it will affect the efficiency adversely. Few parameters can be
incorrect in a switching power supply without creating losses and potentially damaging heat.
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Over Current Protection
The evaluation board is configured with hiccup over-current protection. In the event of an output overload
(approximately 35A) the unit will discharge the softstart capacitor, which disables the power stage. After a
delay the softstart is released. The shutdown, delay and slow recharge time of the softstart capacitor
protects the unit, especially during short circuit event where the stress is highest.
(approximately 35A) the unit will discharge the softstart capacitor, which disables the power stage. After a
delay the softstart is released. The shutdown, delay and slow recharge time of the softstart capacitor
protects the unit, especially during short circuit event where the stress is highest.
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SNVA433A – March 2010 – Revised May 2013
AN-2043 LM5035C Evaluation Board
Copyright © 2010–2013, Texas Instruments Incorporated