Texas Instruments AN-1574 LM5073 User Manual Download Page 19

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Summary of Contents for AN-1574 LM5073

Page 1: ...r optimal solution On board DC DC converter Output voltage 3 3V Maximum output current 3 0A Switching frequency 150kHz Easily reconfigurable for different applications Complete PD interface including...

Page 2: ...it J5 and J6 3 3V output port of the onboard buck regulator J5 is the high potential pin P1 and P2 a pair of pins for quick PoE input connection from a bench power supply to the center taps of the Eth...

Page 3: ...rt pins 2 and 3 to bypass common mode input filter Either of the two settings must be selected Short pins 1 and 2 to use the differential input filter JMP6 Short pins 2 and 3 to bypass the differentia...

Page 4: ...rnal DC DC converter s input capacitance is not enough C8 of the evaluation board can be used Using C8 but excluding L1 JMP6 s three pins should be all shorted together 8 A Note About the Onboard Buck...

Page 5: ...n order to obtain IEEE 802 3af specified maximum power the Aux source voltage should be greater than 20V Otherwise the obtainable power from the Aux source will be limited by the LM5073 s maximum curr...

Page 6: ...d configuration for an IEEE 802 3af fully compliant PD interface with rear Aux power support This configuration is recommended for low voltage Aux power sources such as 12V or 24 ac adapters The minim...

Page 7: ...s R7 may need to be removed or replaced in order to limit the dc current per IEEE 802 3af Refer to LM5073 datasheet for R7 selection Figure 4 IEEE 802 3af Fully Compliant PD Interface with Front Aux P...

Page 8: ...AUX input voltage is not adequate for the controller to start To select this feature install D3 and R25 according to Table 7 and have JMP2 s pins 2 and 3 shorted but pin 1 open A linear regulator to p...

Page 9: ...the bench supply s voltmeter or ammeter if accurate efficiency measurements are desired 14 2 Source Power To fully test the evaluation board for high power PD applications either a high power PSE able...

Page 10: ...mined by R6 of 31 6 This sets the evaluation board to Class 4 which is reserved for future use per IEEE 802 3af namely the high power application If the proper response is not observed during both det...

Page 11: ...s complete the DC DC converter enters steady state operation and output regulation will be achieved 16 Aux Power Up Sequence The FAUX input power up sequence is similar to that of the PoE input with t...

Page 12: ...The input current 1A div Figure 8 RAUX Power Up Sequence 18 Ripple Voltage and Current Figure 9 shows the output ripple voltage and input ripple current when the evaluation board is configured to use...

Page 13: ...ete Evaluation Board Schematic Figure 10 The Complete Schematic of the Evaluation Board Figure 11 Silkscreen 13 SNVA214A April 2007 Revised April 2013 AN 1574 LM5073 Evaluation Board Submit Documentat...

Page 14: ...Evaluation Board Schematic www ti com Figure 12 Top Layer 14 AN 1574 LM5073 Evaluation Board SNVA214A April 2007 Revised April 2013 Submit Documentation Feedback Copyright 2007 2013 Texas Instruments...

Page 15: ...0805 KEMET 0 047 F 50V C5 NU NOT POPULATED C6 NU NOT POPULATED C7 NU NOT POPULATED C8 EEV HA2A220P CAPACITOR AL ELEC PANASONIC 22 F 100V C9 NU NOT POPULATED C10 NU NOT POPULATED C11 C2012X5R1C102K CAP...

Page 16: ...4 2 00 01 00 00 080 POST MILL MAX JMP1 A26542 ND CONN HEADER VERT 2POS DIGI KEY 2 PIN HEADER JMP2 A26544 ND CONN HEADER VERT 3POS DIGI KEY 3 PIN HEADER JMP3 A26544 ND CONN HEADER VERT 3POS DIGI KEY 3...

Page 17: ...ISTOR 3 32K R11 CRCW12062492F RESISTOR 24 9K R12 CRCW12062492F RESISTOR 24 9K R13 NU NOT POPULATED R14 NU NOT POPULATED R15 NU NOT POPULATED R16 NU NOT POPULATED R17 CRCW2512100J RESISTOR 1 Ohm 1W R18...

Page 18: ...5mA 75V D6 CMHD4448 DIODE SOD123 CENTRAL 125mA 75V Q1 CMPT2222A BIPOLAR NPN SOT 23 CENTRAL 0 6A 60V Q2 SI4470EY MOSFET N CH SO 8 VISHAY 12A 60V R13 CRCW1206100RJ RESISTOR 100 R14 CRCW12062001F RESISTO...

Page 19: ...sponsible for compliance with all legal regulatory and safety related requirements concerning its products and any use of TI components in its applications notwithstanding any applications related inf...

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