LM5071HEEVAL National Semiconductor, LM5071HEEVAL Datasheet

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LM5071HEEVAL

Manufacturer Part Number
LM5071HEEVAL
Description
Manufacturer
National Semiconductor
Datasheet
1.LM5071HEEVAL.pdf (14 pages)

Specifications of LM5071HEEVAL

Lead Free Status / Rohs Status
Not Compliant
© 2006 National Semiconductor Corporation
LM5071 Evaluation Board
Introduction
The LM5071 evaluation board is designed to provide a low
cost, fully IEEE 802.3af compliant Power over Ethernet
(PoE) power supply, capable of operating with both PoE and
auxiliary (AUX) power sources. The evaluation board fea-
tures the LM5071 PoE Powered Device (PD) interface and
controller integrated circuit (IC) configured in the versatile
flyback topology.
Features of the LM5071 Evaluation
Board:
• Single Isolated 3.3V output
• Dual Isolated 5V and 3.3V outputs supported (see Figure
• Maximum output current 3.3A
• Input voltage range (full power):
• Measured maximum efficiency:
12)
former
With the installed wide-voltage-range EP13 transformer
With the optional, efficiency-optimized EP13 trans-
With the installed wide-voltage-range EP13 transformer
With the optional, efficiency-optimized EP13 trans-
PoE input voltage range: 38 to 60V
AUX input voltage range: 14 to 60V
PoE input voltage range: 38 to 60V
AUX input voltage range: 24 to 60V
DC to DC converter efficiency: 81% at 3A
Overall efficiency (including diode bridge): 78.5% at 3A
AN201758
National Semiconductor
Application Note 1430
Youhao Xi
April 2006
• Board Size: 2.75 x 2.00 x 0.66 inches
• Operating frequency: 250 kHz
• Programmed PoE input under-voltage lockout (UVLO)
• Programmed PoE input UVLO hysteresis: 5.9V
This application note focuses on the evaluation board.
Please refer to the datasheet for detailed information about
the complete functions and features of the LM5071 IC.
A Note about Input Potentials
The LM5071 is designed for PoE applications that are typi-
cally -48V systems, in which the notations GND and -48V
normally refer to the high and low input potentials, respec-
tively. However, for easy readability, the LM5071 datasheet
was written in the positive voltage convention with positive
input potentials referenced to the VEE pin of the LM5071.
Therefore, when testing the evaluation board with a bench
power supply, the negative terminal of the power supply is
equivalent to the PoE system’s -48V potential, and the posi-
tive terminal is equivalent to the PoE system ground. To
prevent confusion between the datasheet and this applica-
tion note, the same positive voltage convention is used
herein.
Schematic of the Evaluation Board
Figure 1 shows the schematic of the LM5071 evaluation
board. See the Appendix for the Bill of Materials (BOM).
former
release: 39V Nominal
DC to DC converter efficiency: 84% at 3A
Overall efficiency (including diode bridge): 81.5% at 3A
www.national.com

LM5071HEEVAL Summary of contents

Page 1

... AUX input voltage range 60V • Measured maximum efficiency: With the installed wide-voltage-range EP13 transformer converter efficiency: 81 Overall efficiency (including diode bridge): 78. With the optional, efficiency-optimized EP13 trans- © 2006 National Semiconductor Corporation National Semiconductor Application Note 1430 Youhao Xi April 2006 former converter efficiency: 84 Overall efficiency (including diode bridge): 81 ...

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Connection and Proper Test Methods FIGURE 2. LM5071 Evaluation Board Connections Figure 2 shows the connections for the LM5071 evaluation board. The LM5071 evaluation board has three ports for connec- tions. The RJ45 receptacle connector is for PoE input, the ...

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Power Up (Continued) is observed likely that the AUX power feed polarity is reversed. After successful operation is observed, full power testing can begin. PD Interface Operating Modes When connecting into the PoE system, the evaluation board’s Powered ...

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Input UVLO and UVLO Hysteresis The input UVLO threshold and UVLO hysteresis can be independently programmed by selecting R5 and R37. The UVLO release threshold level is mainly determined by the ratio of R37 and R5, as governed by the ...

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The Factors Limiting the Minimum Operating Input Voltage The LM5071 is capable of operating with an AUX power source of as low as 10.5V (after the AUX input OR-ing-diode drop, the VIN pin sees 9.5V). However, the minimum oper- ating ...

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Performance Characteristics (Continued) Horizontal Resolution: 5 ms/Div. Trace 1: RTN pin, elevated until UVLO release. 5V/Div. Trace 2: SS pin, starts when VCC achieves minimum regu- lation. 5V/Div. < Trace 3: VCC, starts when RTN 1.5V, elevated by auxiliary winding. ...

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Performance Characteristics (Continued) Horizontal Resolution: 2 ms/Div. Trace 1: RTN pin of the LM5071 IC, 1V/Div. Trace 2: Softstart pin, 2V/Div. Trace 3: Test board input current, 200 mA/Div. FIGURE 7. Shorted Output Fault Condition / Automatic Re-try STEP RESPONSE ...

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Performance Characteristics (Continued) Horizontal Resolution: 1 µs/Div. Trace 1: Reverse voltage across output rectifier diode D5, 5V/Div. FIGURE 11. Output Rectifier Reverse Voltage Waveform Reconfiguration Of The Evaluation Board For 3.3V And 5V Dual Outputs The standard evaluation circuit can ...

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A Note For Using The Efficiency Optimized EP13 Power Transformer DA2383 Please note that the DA2383 is a single output transformer. When using a DA2383 to obtain better efficiency (See Figure 3 for the applicable load and AUX input voltage ...

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Appendix: LM5071 Evaluation Board Bill of Materials ITEM PART NUMBER R1 CRCW2512100J R2 CRCW2512100J R3 CRCW120649R9F R4 CRCW 120610R0F R5 CRCW08055903F R6 CRCW08051001F R7 CRCW080510R0F R9 CRCW08051000F R11 CRCW08051002F R12 CRCW08052432F R13 CRCW08052612F R14 CRCW12060R301F R15 CRCW12060R301F R16 CRCW08051001F R17 ...

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... BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. ...