LM5072EVAL National Semiconductor, LM5072EVAL Datasheet - Page 10

• Manufacturer Part Number: LM5072EVAL
• Description: BOARD EVALUATION LM5072
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM5072EVAL

• Main Purpose: Special Purpose DC/DC, Power Over Ethernet
• Outputs And Type: 1, Isolated
• Power - Output: 9.9W
• Voltage - Output: 3.3V
• Current - Output: 3A
• Voltage - Input: 38 ~ 60V
• Regulator Topology: Flyback
• Frequency - Switching: 250kHz
• Board Type: Fully Populated
• Utilized Ic / Part: LM5072
• Lead Free Status / RoHS Status: Not applicable / Not applicable

www.national.com
Performance Characteristics
STEP RESPONSE
Figure 11 shows the step load response at Vin = 48V.
Horizontal Resolution: 0.2 ms/Div.
Trace 1: Output voltage (AC coupled), 200 mV/Div.
Trace 2: Output current (DC coupled), 0.5 A/Div.
RIPPLE VOLTAGE/CURRENT
Figure 12 shows the output ripple voltage and input ripple
current for 48V input voltage and 3.3A output. The input
ripple current is reduced to less than 5 mA pk-pk by the input
filter inductor.
Horizontal Resolution: 0.2 ms/Div.
Trace 1: Output voltage (AC coupled), 20 mV/Div.
Trace 2: Input current (AC coupled), 50 mA/Div.
Vin=48V, Iout=3.3A
FLYBACK TRANSFORMER WAVEFORMS
Figures 13 and 14 show typical flyback transformer wave-
forms: the drain to source voltage of the main switch Q1 and
the reverse voltage of the rectifier diode D5, respectively, at
48V input voltage and 3.3A output.
(Continued)
FIGURE 11. Regulator Response to Step Load
FIGURE 12. Ripple Currents and Voltages
20187212
20187213
10
Horizontal Resolution: 1 µs/Div.
Trace 1: Drain to source voltge of main switch Q1, 50V/Div.
Vin=48V, Iout=3.3A
Horizontal Resolution: 1 µs/Div.
Trace 1: Reverse voltage across output rectifier diode D5,
5V/Div.
Vin=48V, Iout=3.3A
Reconfiguration of the Evaluation
Board for 3.3V And 5V Dual
Outputs
The standard evaluation circuit can be easily reconfigured
into a 2A 3.3V and 0.6A 5.5V dual output power supply. To
reconfigure the board for dual output, populate the compo-
nents for the 5.5V output rail as shown in Figure 15. These
components are listed in the additional BOM list in the Ap-
pendix.
FIGURE 13. Flyback Transformer Waveforms
FIGURE 14. Flyback Transformer Waveforms
20187214
20187215