Datasheet

Other Performance Characteristics
When applying power to the LM5039 evaluation board a cer-
tain sequence of events occurs. Soft-start capacitor values
and other components allow for a minimal output voltage for
a short time until the feedback loop can stabilize without over-
shoot. Figure 7 shows the output voltage during a typical start-
up with a 48V input and a load of 30A. There is no overshoot
during start-up.
Figure 8 shows the transient response for a load of change
from 5A to 25A. The upper trace shows minimal output volt-
age droop and overshoot during the sudden change in output
current shown by the lower trace.
30112708
Conditions: Input Voltage=48V
Output Current=5A
Trace 1: Output Voltage Volts/div=500mV
Horizontal Resolution =2.0 ms/div
FIGURE 7.
30112709
Conditions: Input Voltage=48V
Output Current=15A to 22.5A
Upper Trace: Output Voltage Volts/div=50mV
Lower Trace: Output Current = 15A to 22.5A to 15A
Horizontal Resolution =0.5 ms/div
FIGURE 8.
Figures 9 and 10 show the drain voltage of Q1 with a 25A
load. Figure 9 represents an input voltage represents an input
voltage of 36V and Figure 10 represents an input voltage of
72V.
30112710
Conditions: Input Voltage =36V
Output Current=5A
Trace 1: Q1 Drain Voltage Volts/div=10V
Horizontal Resolution= 1 us/div
FIGURE 9.
30112721
Conditions: Input Voltage =72V
Output Current=5A
Trace 1: Q1 Drain Voltage Volts/div=10V
Horizontal Resolution= 1 us/div
FIGURE 10.
Figure 11 shows typical output ripple seen directly across the
output capacitor, for an input voltage of 48V and a load of 30A.
This waveform is typical of most loads and input voltages.
30112724
Conditions: Input Voltage =48V
Output Current=5A
Trace 1: Output Voltage Volts/div=20mV
Horizontal Resolution= 1 us/div
FIGURE 11.
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