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PowerDsine Presentation October 2005 Page

17

www.PowerDsine.com

802.3af modular installed base considerations

802.3af minimum PSE voltage: 44V

Modular switches

– 44V power supply is deployed with chassis

– Customer expectation: 802.3at-blades added to 802.3af-chassis

– 51V minimum at PSE

Æ

Boost converter MUST be placed on blade

More power dissipation at blade

More components added to crowded blade

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Содержание IEEE802.3

Страница 1: ...www powerdsine com IEEE802 3at Task Force Technical and market considerations regarding PoEp output voltage range Vancouver BC November 2005 Arkadiy Peker Daniel Feldman Yair Darshan ...

Страница 2: ...www powerdsine com Part A Technical Considerations regarding PoEp output voltage range ...

Страница 3: ...PowerDsine Presentation October 2005 Page 3 www PowerDsine com Objectives To discuss optimum voltage range for PoEp To show advantages of having PoEp minimum voltage of 51V ...

Страница 4: ...m power within practical limit Power Dissipation Safety consideration Power dissipation is function of the current Increasing minimum voltage reduces current level for the same load power or Increasing Power delivery to the load for a given current value Hence same infrastructure delivers more power to PDs for given PSE PS size and cost Bottom line more applications may supported Larger POEp marke...

Страница 5: ...livered to the load by four pairs It means that at 51V for the same power dissipation on the cable power delivered to the load will be 4 9W more then at 44V The advantage of higher voltage is further increased for higher currents than 0 35A 32 64W 27 74W Maximum power delivered to the PD 3 06W 3 06W Power dissipation on 4 pair 51V 44V ...

Страница 6: ...ed to be delivered to PD by four pair is 40W Power dissipation on a cables for 51V PSE will be 2 45W less then for 44V Advantages of higher voltage is increase with increasing power level 0 89 0 84 System efficiency for 500W PSE PS 44 88W 47 52W PSE power 4 85W 7 3W Power dissipation on a cables 4P 0 44A 0 54A Current per pair 40W 40W Pd power 51V 44V ...

Страница 7: ...mum voltage 51V required smaller PSE power supply then at 44V for the same load The technical advantage is clear for using higher voltage minimum voltage level for POEp PSE Let consider different options in PoEp Power architectures AC input and battery back up AC UPS input ...

Страница 8: ...PowerDsine Presentation October 2005 Page 8 www PowerDsine com PoEp Power Architecture AC Input ...

Страница 9: ...munication have one of the terminal grounded mostly positive This would prevent direct use of this batteries in POE and would require to have isolated converter between batteries and PSE regardless of output voltage considerations Therefore increasing output voltage to 51V would not add any system cost But boost converter would be useful even in case of isolated batteries DC UPS which really is no...

Страница 10: ...ry cable and PSE voltage drop Mosfet and CS resistor it would require Low Voltage Disconnect to shutdown battery at 46V in order to have 44V on the PSE output It means battery life would not be fully utilize Adding boost converter which would keep output voltage of the system constant in our case 51V would extend batteries capabilities on 15 in POE systems ...

Страница 11: ...PowerDsine Presentation October 2005 Page 11 www PowerDsine com PoEp Power Architecture AC UPS ...

Страница 12: ...of power supply with 44V or 51V outputs is approximately the same But under the same conditions 51V output power supply will have higher efficiency then 44V PS Estimated cost of additional boost circuitry for supporting the change from 45V to 52V for 500W power supply is about 10 cost of power supply ...

Страница 13: ...PowerDsine Presentation October 2005 Page 13 www PowerDsine com PoEp with Boost circuit Battery AC POE PS PWM Rs Lb Qb Db Cb R1 R2 ...

Страница 14: ...ower Add Power Circuit AC or Battery POE PS V 51V Vout 51V For 48V 250W power supply maximum power for add power converter would be 52V 48V 500 48 42W or about 9 of 500W PS cost However taken in account improved system efficiency total cost of ownership would remain about the same ...

Страница 15: ...ould increase overall system efficiency Costs of 51V PS and 48V PS are approximately the same and from technical point of view would be beneficial to have minimum 51V in PoEp PSE Regardless of output voltage consideration adding boost circuit for system with batteries back up would increase battery useful life in POE systems ...

Страница 16: ...www powerdsine com Part B Market considerations regarding 802 3at output voltage range ...

Страница 17: ...onsiderations 802 3af minimum PSE voltage 44V Modular switches 44V power supply is deployed with chassis Customer expectation 802 3at blades added to 802 3af chassis 51V minimum at PSE Æ Boost converter MUST be placed on blade More power dissipation at blade More components added to crowded blade ...

Страница 18: ...owerDsine com How to solve the conflict The Conflict is 51V is the Technically preferred solution More power at low cost Bigger addressable market 44V addresses the existing modular installed base Impossible to replaced 44V power supplies on the field ...

Страница 19: ...ation in 802 3at including Class 4 should be mandatory and not optional The enhanced classification table will be divided to two parts See details in An Extended Classification Proposal Proposal 1 Vancouver BC Nov 2005 Part a power classes that can work with either 44V or 51V Part b power classes that can work only with 51V minimum at the PSE This may be documented in the Informative section of th...

Страница 20: ...in any other aspect are anyway able to power 802 3at complaint PD s with classes of Part a Hence all OK so far Supplies power only if capable of Like we do today in IEEE802 3af 802 3af PSE classification including class 4 should be mandatory In order to PSE to know if to power or not To differentiate between 802 3af PD and PoEp PD 802 3at PSE extended classification is optional Like classification...

Страница 21: ...w to support most of the higher power classed even with 44V enhanced classification part A group which is built in benefit however it doesn t concerns the other standard requirements nor affect it It is perfectly OK that Switch PSE is 802 3at compliant as long as its Power Supply supports 51V If PSE PS Power Supply is 44V then 802 3at PSE is not compliant but working and covered most of high power...

Страница 22: ...PowerDsine Presentation October 2005 Page 22 www PowerDsine com Discussion ...

Страница 23: ...PowerDsine Presentation October 2005 Page 23 www PowerDsine com References An Extended Classification Proposal Proposal 1 Yair Darshan Vancouver BC November 2005 ...

Страница 24: ...PowerDsine Presentation October 2005 Page 24 www PowerDsine com Annex A Enhanced Classification table Example for group A and group B With Pmax 40W Group B ...

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