LM25576EVAL National Semiconductor, LM25576EVAL Datasheet - Page 2

• Manufacturer Part Number: LM25576EVAL
• Description: BOARD EVALUATION FOR LM25576
• Manufacturer: National Semiconductor
• Series: PowerWise®, SIMPLE SWITCHER®r

Specifications of LM25576EVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 5V
• Current - Output: 3A
• Voltage - Input: 7 ~ 42V
• Regulator Topology: Buck
• Frequency - Switching: 300kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM25576
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -
• Other names: *LM25576EVAL

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current limit of the source supply to provide about 1.5 times
the anticipated wattage of the load. As you remove the con-
nection from the shutdown pin to ground, immediately check
for 5 volts at the output.
A quick efficiency check is the best way to confirm that ev-
erything 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.
OVER CURRENT PROTECTION
The evaluation board is configured with over-current protec-
tion. The output current is limited to approximately 4.5A. The
thermal stress is quite severe while in an overloaded condi-
tion, limit the duration of the overload and provide sufficient
cooling (airflow).
SYNCHRONIZATION
A SYNC pin has been provided on the evaluation board. This
pin can be used to synchronize the regulator to an external
clock or multiple evaluation boards can be synchronized to-
gether by connecting their SYNC pins together. Refer to the
LM25576 datasheet for complete information.
Performance Characteristics
EFFICIENCY PLOTS
Figure 1 shows the conversion efficiency versus output cur-
rent for several input voltage conditions.
FIGURE 1.
30007102
2
TURN-ON WAVEFORM
When applying power to the LM25576 evaluation board a
certain soft-start sequence occurs. Figure 2 shows the output
voltage during a typical start-up sequence.
Conditions: Input Voltage = 36VDC, Output Current = 2A
Trace 1: Output Voltage Volts/div = 2V
Horizontal Resolution = 500 µsec/div
OUTPUT RIPPLE WAVEFORM
Figure 3 shows the output voltage ripple. This measurement
was taken with a very short ground clip and 20MHZ bandwidth
limiting.
Conditions: Input Voltage = 36VDC Output Current = 2A Bandwidth Limit =
20MHz
Trace 1: Output Ripple Voltage Volts/div = 50mV
Horizontal Resolution = 2 µsec/div
FIGURE 2.
FIGURE 3.
30007103
30007104