LM5035EVAL National Semiconductor, LM5035EVAL Datasheet - Page 4

• Manufacturer Part Number: LM5035EVAL
• Description: BOARD EVALUATION LM5035
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5035EVAL

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Isolated
• Voltage - Output: 3.3V
• Current - Output: 30A
• Voltage - Input: 36 ~ 75V
• Regulator Topology: Buck
• Frequency - Switching: 400kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM5035
• Lead Free Status / RoHS Status: Not applicable / Not applicable
• Power - Output: -

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Performance Characteristics
TURN-ON WAVEFORMS
When applying power to the LM5035 evaluation board a
certain sequence of events occurs. Soft-start capacitor val-
ues and other components allow for a minimal output voltage
for a short time until the feedback loop can stabilize without
overshoot. Figure 1 shows the output voltage during a typical
start-up with a 48V input and a load of 5A. There is no
overshoot during startup.
OUTPUT RIPPLE WAVEFORMS
Figure 2 shows the transient response for a load change
from 15A to 22.5A. The upper trace shows minimal output
voltage droop and overshoot during the sudden change in
output current shown by the lower trace.
Conditions: Input Voltage = 48VDC
Output Current = 5A
Trace 1: Output Voltage Volts/div = 500mV
Horizontal Resolution = 0.5ms/div
Conditions: Input Voltage = 48VDC
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 = 0.5ms/div
FIGURE 1.
FIGURE 2.
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Conditions: Input Voltage = 48VDC
Output Current = 30A
Bandwidth Limit = 20MHz
Trace 1: Output Ripple Voltage Volts/div = 20mV
Horizontal Resolution = 1µs/div
Figure 3 shows typical output ripple seen across the output
terminals (with standard 10µF and 1µF ceramic capacitors)
for an input voltage of 48V and a load of 30A. This waveform
is typical of most loads and input voltages.
Figures 4 and 5 show the drain voltage of Q1 with a 5A load.
Figure 4 represents an input voltage of 36V and Figure 5
represents an input voltage of 72V.
Figure 6 shows the gate voltages of the synchronous recti-
fiers. The deadtime provided by the 20kΩ DLY resistor is
difficult to see at this timescale.
Conditions: Input Voltage = 36VDC
Output Current = 5A
Trace 1: Q1 drain voltage Volts/div = 10V
Horizontal Resolution = 1µs/div
FIGURE 3.
FIGURE 4.
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